Canada FluWatch Weekly Reports 2012-2013 Season Week 19

Pathfinder · #1 October 1st, 2012, 05:53 PM

August 26 to September 8, 2012 (Weeks 35 & 36)

Posted 2012-09-14For readers interested in the PDF version, the document is available for downloading or viewing:
2011-2012 FluWatch: August 26 to September 8, 2012 (Weeks 35 & 36) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada remains low; however several regions have reported either sporadic or localized activity over the two-week period (in BC, MB, ON & QC)
In weeks 35 and 36, a total of 17 laboratory detections of influenza were reported of which 82.4% were for influenza A viruses (7 A(H3) and 7 A(un-subtyped)) and 17.6% for influenza B viruses
One region (in MB) reported localized activity in week 36 due to an outbreak in a long-term care facility
No influenza-associated hospitalizations were reported over the two-week period
The ILI consultation rate in weeks 35 and 36 were within the expected levels for this time of year

NOTE: This is the first surveillance report for the 2012-2013 influenza season.Bi-weekly reports will continue until October 12, 2012. However, laboratory detections reported through the RVDSS and influenza activity level maps will be updated weekly on the FluWatch website.

Influenza Activity (geographic spread) and Outbreaks

In week 35, 2 regions (within BC & ON) reported sporadic activity while the rest reported no activity. In week 36, 1 region (within MB) reported localized activity, 2 regions (within ON & QC) reported sporadic activity and the rest reported no activity (see Figure 1). Note that no data was received from AB, SK, NS, PEI and YT for week 35 and no data was received from SK, PEI, NL and YT for week 36. One new outbreak was reported in week 36 in a long-term care facility (Figure 3) in MB and was due to influenza A/H3.
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 36

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N=56)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The proportion of positive influenza tests increased slightly from two weeks ago (when the percent positive was 0.2%) and was 0.9% in week 35 and 0.6% in week 36 (Figure 4 & 5). The proportion of positive detections for influenza A (0.8% in week 35 and 0.4% in week 36) was slightly higher than the proportion positive for influenza B detections (0.1% and 0.2% respectively). Over the two week period, influenza A detections were reported in BC, AB, MB, ON, QC & NL while influenza B detections were reported in AB, SK & QC.
Cumulative to date of influenza virus detections by type/subtype is as follows: 82.4% influenza A (50.0% - A(H3) and 50.0% - unsubtyped) and 17.6% influenza B (Table 1).
Detailed information on age and type/subtype of the positive influenza cases to date will be presented once more information becomes available (Table 2).
The percentage positive for rhinovirus detections was similar to previous weeks (18.0% & 23.1% in weeks 35 & 36 respectively) and remains the highest compared to the other respiratory viruses. The percentage positive for parainfluenza viruses continued to decline and was 1.7% in week 36. The percentage positive for the other respiratory viruses in week 36 remained low: RSV-.7%; adenovirus-1.1%; hMPV-0.8%; and coronavirus-0.7% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (August 26 to September 8, 2012)						Cumulative (August 28, 2012 to September 8, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	2	0	1	0	1	0	2	0	1	0	1	0
AB	2	0	1	0	1	1	2	0	1	0	1	1
SK	0	0	0	0	0	1	0	0	0	0	0	1
MB	3	0	3	0	0	0	3	0	3	0	0	0
ON	5	0	2	0	3	0	5	0	2	0	3	0
QC	1	0	0	0	1	1	1	0	0	0	1	1
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	1	0	0	0	1	0	1	0	0	0	1	0
Canada	14	0	7	0	7	3	14	0	7	0	7	3

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (August 26 to September 8, 2012)					Cumulative (Aug. 28, 2012 to September 8, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	0	0	0	0	0	0	0	0	0	0
5-19	0	0	0	0	0	0	0	0	0	0
20-44	0	0	0	0	0	0	0	0	0	0
45-64	0	0	0	0	0	0	0	0	0	0
65+	0	0	0	0	0	0	0	0	0	0
Unknown	0	0	0	0	0	0	0	0	0	0
Total	0	0	0	0	0	0	0	0	0	0

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

The National Microbiology Laboratory (NML) has not received any influenza virus specimens for strain characterization since the start of the 2012-2013 influenza season. However, of the influenza viruses characterized in the months of July and August 2012, the majority (52%) were antigenically similar to B/Wisconsin/01/2010 (Yamagata lineage) while the rest were antigenically similar to either A/Perth/16/2009 (24%) or B/Brisbane/60/2008 (Victoria lineage) (24%). The distribution of influenza strain characterizations for the 2011-2012 influenza season are presented in Figure 6.
Figure 6. Influenza strain characterizations, Canada, 2011-2012, N = 1, 443

Note: The recommended components for the 2011-2012 Northern Hemisphere influenza vaccine include: A/Perth/16/2009 (H3N2), A/California/7/2009 (H1N1) and B/Brisbane/60/2008.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

The National Microbiology Laboratory (NML) has not received any influenza virus specimens for antiviral resistance testing since the start of the 2012-2013 influenza season. However, antiviral resistance findings from the 2011-2012 influenza season are presented in Table 3.

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2011-2012**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	256	0	255	0	450	449 (99.8%)
A (H1N1)	256	0	256	0	356	356 (100%)
B	967	0	967	0	NA ^*	NA ^*
TOTAL	1479	0	1478	0	806	805 (99.9%)

Influenza-like Illness (ILI) Consultation Rate

The national ILI consultation rate remained similar to the rates from two week prior and was 7.6 ILI consultations per 1,000 patient visits in week 35 and 5.6 per 1,000 visits in week 36; both rates were within the expected levels for this time of year (Figure 7). The highest consultation rates by age group were observed in those <5 years of age in both weeks (12.2/1,000 in week 35 and 18.1/1,000 in week 36.
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note:No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.
Influenza Hospitalizations and Deaths (Aggregate Surveillance System)
No laboratory-confirmed influenza-associated hospitalizations, ICU admissions or deaths have been reported since the start of the 2012-2013 influenza season.
Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.
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Pathfinder · #2 October 1st, 2012, 05:55 PM

Fluwatch Report: September 9 to September 22, 2012 (Weeks 37 & 38)

Posted 2012-09-28For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: September 9 to September 22, 2012 (Weeks 37 & 38) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada remains low as only a few regions reported sporadic activity over the two-week period (in ON, QC & NL)
In weeks 37 and 38, a total of 5 laboratory detections of influenza were reported, all of which were for influenza A viruses [1 A(H1N1)pdm09 and 4 A(un-subtyped)]
One influenza A-associated hospitalization (in a person >20 years of age) was reported over the two-week period
The ILI consultation rate increased in week 38 to 17.8 per 1,000 patient visits but remains within the expected level for this time of year

NOTE: Bi-weekly reports will continue until October 12, 2012. However, laboratory detections reported through the RVDSS and influenza activity level maps will be updated weekly on the FluWatch website.

Influenza Activity (geographic spread) and Outbreaks

In week 37, 1 region (within NL) reported sporadic activity while the rest reported no activity. In week 38, 3 regions (within ON & QC) reported sporadic activity and the rest reported no activity (see Figure 1). Note that data was not received from SK and PEI for week 37 and from SK for week 38. No new outbreaks of influenza or ILI were reported in weeks 37 and 38 (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 38

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N=58)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests was 0.3% in week 37 and 0.4% in week 38 (Figure 4 and 5). This is a slight decrease from week 36 (0.6%). Over the two week period, only influenza A detections were reported: 20% were A(H1N1)pdm09 and 80% were A unsubtyped (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 88.5% influenza A (47.8% - A(H3), 0.4% - A(H1N1)pdm09 and 47.8% - unsubtyped) and 11.5% influenza B (Table 1).
Detailed information on age and type/subtype of the positive influenza cases to date will be presented once more information becomes available (Table 2).
The percentage positive for rhinovirus detections was similar to the previous week (26.7% & 23.7% in weeks 37 & 38 respectively) and remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 38 remained low: RSV-1.1%; parainfluenza-2.0; adenovirus-1.5%; hMPV-0.0%; and coronavirus-0.7% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (September 9 to September 22, 2012)						Cumulative (August 26, 2012 to September 22, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	0	0	0	0	0	0	3	0	2	0	1	0
AB	1	0	0	1	0	0	3	0	1	1	1	1
SK	1	0	0	0	1	0	1	0	0	0	1	1
MB	0	0	0	0	0	0	3	0	3	0	0	0
ON	2	0	0	0	2	0	9	0	4	0	5	0
QC	1	0	0	0	1	0	2	0	0	0	2	1
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	0	0	0	0	0	0	2	0	1	0	1	0
Canada	5	0	0	1	4	0	23	0	11	1	11	3

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (September 9 to September 22, 2012)					Cumulative (Aug. 26, 2012 to September 22, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that the table will be populated once more data becomes available.
< 5	-	-	-	-	-	-	-	-	-	-
5-19	-	-	-	-	-	-	-	-	-	-
20-44	-	-	-	-	-	-	-	-	-	-
45-64	-	-	-	-	-	-	-	-	-	-
65+	-	-	-	-	-	-	-	-	-	-
Unknown	-	-	-	-	-	-	-	-	-	-
Total	-	-	-	-	-	-	-	-	-	-

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

No data on influenza strain characterizations have been reported by the National Microbiology Laboratory (NML) since the start of the 2012-2013 influenza season. However, of the influenza viruses characterized in the months of July and August 2012, the majority (52%) were antigenically similar to B/Wisconsin/01/2010 (Yamagata lineage) while the rest were antigenically similar to either A/Perth/16/2009 (24%) or B/Brisbane/60/2008 (Victoria lineage) (24%). The distribution of influenza strain characterizations for the 2011-2012 influenza season are presented in Figure 6.
Figure 6. Influenza strain characterizations, Canada, 2011-2012, N = 1, 443

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: A/Perth/16/2009 (H3N2), A/California/7/2009 (H1N1) and B/Brisbane/60/2008.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

No data on antiviral resistance have been reported by the National Microbiology Laboratory (NML) since the start of the 2012-2013 influenza season. However, antiviral resistance findings from the 2011-2012 influenza season are presented in Table 3.

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	256	0	255	0	450	449 (99.8%)
A (H1N1)	256	0	256	0	356	356 (100%)
B	967	0	967	0	NA ^*	NA ^*
TOTAL	1479	0	1478	0	806	805 (99.9%)

Influenza-like Illness (ILI) Consultation Rate

The national ILI consultation rate was below expected levels in week 37 (8.0 ILI consultations per 1,000 patient visits); however the ILI rate increased in week 38 to 17.8/1,000 yet remains within the expected levels for this time of year (Figure 7). The highest consultation rates in week 38 were observed in those between 5-19 years of age (55.0/1,000) and in those <5 years of age (34.1/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note:No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.
Influenza Hospitalizations and Deaths (Aggregate Surveillance System)
In weeks 37 and 38, one laboratory-confirmed influenza A-associated hospitalization was reported in NL. The case was >20 years of age and was admitted to ICU. This was the first influenza-associated hospitalization reported this season.
Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #3 October 12th, 2012, 04:30 PM

Fluwatch Report: September 23 to October 6, 2012 (Weeks 39 & 40)

Posted 2012-10-12For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: September 23 to October 6, 2012 (Weeks 39 & 40) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

Influenza activity in Canada remains low but has increased slightly since the last report as two regions (in AB & ON) reported localized influenza activity
In weeks 39 and 40, a total of 11 laboratory detections of influenza were reported, the majority (92%) of which were for influenza A viruses [5 A(H3), 4 A(H1N1)pdm09, 2 A(un-subtyped) and 1 B]
Two new influenza outbreaks were reported in week 40: 1 in a LTCF and 1 other
Three influenza A-associated hospitalizations (in persons ≥65 years of age) were reported over the two-week period
The ILI consultation rate increased slightly in week 40 to 18.6 per 1,000 patient visits but remains within the expected level for this time of year

NOTE: Weekly FluWatchreporting will start on October 19, 2012 and will continue until May 2013.

Influenza Activity (geographic spread) and Outbreaks

In week 39, 2 regions (within BC & ON) reported sporadic activity while the rest reported no activity. In week 40, 2 regions (within AB & ON) reported localized activity, 1 region (within ON) reported sporadic activity and the rest reported no activity (see Figure 1). Note that data was not received from AB & SK for week 39 and from SK & PEI for week 40. Two new influenza outbreaks were reported in week 40: 1 in a long-term care facility (LCTF) and 1 other type of facility (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 40

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests was 0.3% in week 39 and 0.4% in week 40 (Figure 4 and link to figure 55). and is similar to the percentage observed in week 38 (0.3%). Of the influenza viruses detected over the two week period (n=12), 92% were positive for influenza A viruses (of which 45% were A(H3), 36% were A(H1N1)pdm09 and 18% were A unsubtyped) and 8% were influenza B viruses (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 89.5% influenza A (47.1% - A(H3), 14.7% - A(H1N1)pdm09 and 38.2% - unsubtyped) and 10.5% influenza B (Table 1).
Detailed information on age and type/subtype of the positive influenza cases to date will be presented once more information becomes available (Table 2).
The percentage positive for rhinovirus detections increased over the two week period (31.5% & 32.8% in weeks 39 & 40 respectively) and remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 40 remained low: RSV-1.8%; parainfluenza-3.1%; adenovirus-1.1%; hMPV-0.3%; and coronavirus-0.3% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (September 23 to October 6, 2012)						Cumulative (August 26, 2012 to October 6, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	1	0	1	0	0	0	4	0	3	0	1	0
AB	5	0	1	4	0	0	8	0	2	5	1	1
SK	0	0	0	0	0	0	1	0	0	0	1	1
MB	0	0	0	0	0	0	3	0	3	0	0	0
ON	5	0	3	0	2	1	14	0	7	0	7	1
QC	0	0	0	0	0	0	2	0	0	0	2	1
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	0	0	0	0	0	0	2	0	1	0	1	0
Canada	11	0	5	4	2	1	34	0	16	5	13	4

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (September 23 to October 6, 2012)					Cumulative (Aug. 26, 2012 to October 6, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that the table will be populated once more data becomes available.
< 5	-	-	-	-	-	-	-	-	-	-
5-19	-	-	-	-	-	-	-	-	-	-
20-44	-	-	-	-	-	-	-	-	-	-
45-64	-	-	-	-	-	-	-	-	-	-
65+	-	-	-	-	-	-	-	-	-	-
Unknown	-	-	-	-	-	-	-	-	-	-
Total	-	-	-	-	-	-	-	-	-	-

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the 2012-2013 influenza season, the National Microbiology Laboratory (NML) has antigenically characterized 1 influenza B virus; the virus was antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage)(Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 1

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 1 influenza virus for resistance to oseltamivir and 1 for zanamivir and it was found that the virus tested was sensitive to oseltamivir and zanamivir. A total of 3 influenza A(H3N2) viruses were tested for amantadine resistance and all 3 viruses tested were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	0	0	0	0	3	3 (100%)
A (H1N1)	0	0	0	0	0	0
B	1	0	1	0	NA ^*	NA ^*
TOTAL	1	0	1	0	3	3 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate for week 39 was 11.8 ILI consultations per 1,000 patient visits and in week 40 was 18.6/1,000; both were within expected levels for this time of year (Figure 7). The highest consultation rates in week 40 were observed in those <5 years of age (49.3/1,000) and those ≥65 years of age (35.5/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)

In weeks 39 and 40, 3 laboratory-confirmed influenza A-associated hospitalizations were reported (from AB & ON). All cases were ≥65 years of age.

To date this season, 4 influenza A-associated hospitalizations have been reported from 3 provinces (AB, ON & NL); all were ≥ 65 years of age. Of the influenza A hospitalizations where subtype was available (2), all were due to influenza A(H1N1)pdm09. There has been 1 hospitalisation for which admission to ICU was required (from NL). To date this season, no influenza-associated deaths have been reported.

Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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International Influenza Update

WHO: Influenza transmission in all reporting countries in the temperate regions of the northern hemisphere is still minimal and is at inter-seasonal levels. In the tropical areas most countries are reporting low or decreasing trends of influenza virus detections. The exceptions are Costa Rica in the Americas and India; Nepal, Lao PDR and Thailand in Asia. In Sub-Saharan Africa, Cameroon has reported an increase in influenza virus detections. It appears that the influenza season in the temperate countries of the southern hemisphere has come to an end.
World Health Organization influenza update

United States: The proportion of tests positive for influenza viruses increased slightly in week 39 (3.6%) compared to previous weeks (3.1% in week 38 and 2.7% in week 37). Of the positive influenza detections reported during week 39, 55% were positive for influenza B viruses. Of the 20 influenza A viruses for which subtype information was available, 85% were A(H3) and 15% were A(H1N1)pdm09. All other indicators of influenza activity remained low.
Centers for Disease Control and Prevention seasonal influenza report

Europe: In week 40, influenza activity in the European Region remained low. None of the 282 samples collected from sentinel sources were positive for influenza virus; 15 samples from non-sentinel sources were positive for influenza viruses (4 influenza A(H1N1)pdm09, 1 influenza A(H3N2), 6 un-subtyped and 4 influenza B). ILI and ARI consultation rates are at low levels, which is usual for this time of year.
EuroFlu weekly electronic bulletin

Human Avian and Swine Influenza Updates

H5N1
No cases of human avian influenza A/H5N1 infection have been reported by the WHO since August 10, 2012. A summary of the latest WHO Human-Animal Interface Risk Assessment

(as of October 1, 2012) is available on the WHO webpage.
WHO Avian influenza situation updates

H1N1 variant (H1N1v)
In week 38, a case of human infection with influenza A(H1N1) variant (H1N1v) virus was reported in Ontario, Canada. The case was an adult male with underlying risk factors who developed symptoms at the end of August and was hospitalized with pneumonia in September. He had occupational exposure to swine. No additional cases have been reported. This is the first time that an H1N1v virus has been detected in Canada with the matrix (M) gene from the influenza A(H1N1)pdm09 virus. Based on its similarity to the H1N1 virus that has circulated in humans since 2009, it is expected that the 2012-2013 seasonal influenza vaccine is likely to protect against the H1N1v influenza virus, although the seasonal influenza vaccine may not protect people against some other variant influenza viruses that are very different from currently circulating human influenza viruses.

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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

Pathfinder · #4 October 19th, 2012, 05:51 PM

Fluwatch Report: October 7 to October 13, 2012 (Week 41)

Posted 2012-10-19For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: October 7 to October 13, 2012 (Week 41) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada remains low but has increased slightly from last week as more regions have reported localized and sporadic influenza activity
In week 41, a total of 17 laboratory detections of influenza were reported, the majority (94%) of which were for influenza A viruses [8 A(H3), 1 A(H1N1)pdm09, 7 A(un-subtyped) and 1 B]
Four new influenza outbreaks were reported in week 41: 3 in LTCFs and 1 other
One influenza A-associated hospitalization (in a person ≥65 years of age) was reported in week 41
The ILI consultation rate declined in week 41 to 10.2 per 1,000 patient visits is below the expected level for this time of year

Influenza Activity (geographic spread) and Outbreaks

In week 41, 3 regions (within AB & ON) reported localized activity, 6 regions (within BC, AB, ON & QC) reported sporadic activity and the rest reported no activity (see Figure 1). Note that data was not received from SK for week 41. Four new influenza outbreaks were reported in week 41: 3 in long-term care facilities (LCTF) and 1 other type of facility (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 41

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

† sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased slightly from the previous week from 0.4% in week 40 to 0.9% in week 41 (Figure 4 and link to figure 55). Of the influenza viruses detected this week (n=17), 94% were positive for influenza A viruses (of which 50% were A(H3), 6.2% were A(H1N1)pdm09 and 43.8% were A unsubtyped) and 6% were influenza B viruses (Table 1).

Cumulative influenza virus detections by type/subtype to date are as follows: 90.7% influenza A (51.0% - A(H3), 12.2% - A(H1N1)pdm09 and 36.7% - unsubtyped) and 9.3% influenza B (Table 1).

To date this season, individuals aged 65 years and older make up the largest proportion of all influenza cases. Additional information on age and type/subtype of the positive influenza cases will be presented in Table 2 once more information becomes available.

The percentage positive for rhinovirus detections declined from the previous week (20.6% in week 41) but remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 41 remained low: RSV-2.0%; parainfluenza-2.4%; adenovirus-1.2%; hMPV-0.2%; and coronavirus-0.7% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (October 7 to October 13, 2012)						Cumulative (August 26, 2012 to October 13, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	1	0	0	0	1	0	5	0	3	0	2	0
AB	6	0	2	1	3	0	14	0	4	6	4	1
SK	0	0	0	0	0	0	1	0	0	0	1	1
MB	0	0	0	0	0	0	3	0	3	0	0	0
ON	7	0	6	0	1	0	21	0	14	0	7	1
QC	2	0	0	0	2	1	4	0	0	0	4	2
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	0	0	0	0	0	0	1	0	1	0	0	0
Canada	16	0	8	1	7	1	49	0	25	6	18	5

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (October 7 to October 13, 2012)					Cumulative (Aug. 26, 2012 to October 13, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that the table will be populated once more data becomes available.
< 5	-	-	-	-	-	-	-	-	-	-
5-19	-	-	-	-	-	-	-	-	-	-
20-44	-	-	-	-	-	-	-	-	-	-
45-64	-	-	-	-	-	-	-	-	-	-
65+	-	-	-	-	-	-	-	-	-	-
Unknown	-	-	-	-	-	-	-	-	-	-
Total	-	-	-	-	-	-	-	-	-	-

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the 2012-2013 influenza season, the National Microbiology Laboratory (NML) has antigenically characterized 1 influenza B virus; the virus was antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 1

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 1 influenza B virus for resistance to oseltamivir and 1 for zanamivir and it was found that the virus tested was sensitive to oseltamivir and zanamivir. A total of 3 influenza A(H3N2) viruses were tested for amantadine resistance and all 3 viruses tested were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	0	0	0	0	3	3 (100%)
A (H1N1)	0	0	0	0	0	0
B	1	0	1	0	NA ^*	NA ^*
TOTAL	1	0	1	0	3	3 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 41 declined slightly from the previous week to 10.2 ILI consultations per 1,000 patient visits. However this rate is below the expected levels for this time of year (Figure 7). The highest consultation rates were observed in those between 5 and 19 years of age (16.6/1,000) and those less than 5 years of age (14.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)

In week 41, one laboratory-confirmed influenza A-associated hospitalization was reported (from ON). The case was ≥65 years of age.
To date this season, 5 influenza A-associated hospitalizations have been reported from 3 provinces (AB, ON & NL); all were ≥ 65 years of age. Of the influenza A hospitalizations where subtype was available (4), 50% were due to influenza A(H1N1)pdm09 and 50% were due to A(H3N2). There has been one hospitalisation for which admission to ICU was required (from NL). To date this season, no influenza-associated deaths have been reported.
Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #5 October 26th, 2012, 04:11 PM

Fluwatch Report: October 14 to October 20, 2012 (Week 42)

Posted 2012-10-26For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: October 14 to October 20, 2012 (Week 42) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

Influenza activity in Canada remains low and was similar to the previous week
In week 42, a total of 17 laboratory detections of influenza were reported, all of which were for influenza A viruses [8 A(H3), 1 A(H1N1)pdm09, 8 A(un-subtyped)]
Two influenza outbreaks in long-term care facilities were reported in week 42
One influenza A-associated hospitalization (in a person ≥65 years of age) was reported in week 42
The ILI consultation rate increased in week 42 to 18.0 per 1,000 patient visits but is within the expected level for this time of year

Influenza Activity (geographic spread) and Outbreaks

In week 42, 4 regions (within AB & ON) reported localized activity, 4 regions (within AB, ON, QC & NL) reported sporadic activity and the rest reported no activity (see Figure 1). Note that data was not received from SK for week 42. Two new influenza outbreaks were reported in week 42 and both were in long-term care facilities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 42

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests declined slightly from the previous week from 1.2% in week 41 to 0.9% in week 42 (Figure 4 and link to figure 55). All of the influenza viruses detected this week (n=17) were positive for influenza A viruses (of which 47.1% were A(H3), 5.9% were A(H1N1)pdm09 and 47.1% were A unsubtyped) (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 93.3% influenza A (54.3% - A(H3), 10.0% - A(H1N1)pdm09 and 35.7% - unsubtyped) and 6.7% influenza B (Table 1).
Detailed information on age and type/subtype were received on 58 cases to date this season (Table 2). The proportions of cases by age group were as follows: 12.1% were < 5 years; 6.9% were between 5-19 years; 19.0% were between 20-44 years; 13.8% were between 45-64 years of age; 48.3% were ≥ 65 years.
The percentage positive for rhinovirus detections increased slightly from the previous week (23.4% in week 42) and remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 42 remained low: RSV-1.9%; parainfluenza-2.9%; adenovirus-1.0%; hMPV-0.2%; and coronavirus-1.2% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
Reporting provinces	Weekly (October 14 to October 20, 2012)						Cumulative (August 26, 2012 to October 20, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	1	0	1	0	0	0	6	0	4	0	2	0
AB	6	0	3	1	2	0	25	0	12	7	6	1
SK	1	0	0	0	1	0	2	0	0	0	2	1
MB	0	0	0	0	0	0	3	0	3	0	0	0
ON	7	0	4	0	3	0	28	0	18	0	10	1
QC	1	0	0	0	1	0	4	0	0	0	4	2
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	1	0	0	0	1	0	2	0	1	0	1	0
Canada	17	0	8	1	8	0	70	0	38	7	25	5

Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
Age groups	Weekly (October 14 to October 20, 2012)					Cumulative (August 26, 2012 to October 20, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	0	0	0	0	0	6	1	5	0	1
5-19	4	0	2	2	0	4	0	2	2	0
20-44	1	1	0	0	0	11	3	4	4	0
45-64	1	0	1	0	0	6	1	2	3	2
65+	5	0	1	4	0	27	2	17	8	1
Unknown	0	0	0	0	0	0	0	0	0	0
Total	11	1	4	6	0	54	7	30	17	4

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 3 influenza viruses [1 A(H3N2) and 2 B]. The influenza A(H3N2) virus (from BC) was antigenically similar to the vaccine strain A/Victoria/361/2011. Both of the influenza B viruses (from ON & QC) were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 3

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 3 influenza viruses [1 A(H3N2) and 2 B] for resistance to oseltamivir and zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 6 influenza A(H3N2) viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	1	0	1	0	6	6 (100%)
A (H1N1)	0	0	0	0	0	0
B	2	0	2	0	NA ^*	NA ^*
TOTAL	3	0	3	0	6	6 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 42 increased from the previous week to 18.0 ILI consultations per 1,000 patient visits and is within the expected levels for this time of year (Figure 7). The highest consultation rates were observed in those less than 5 years of age (30.5/1,000) and those ≥65 years of age (20.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)

In week 42, one laboratory-confirmed influenza A-associated hospitalization was reported (from NL). The case was ≥65 years of age.

To date this season, 6 influenza A-associated hospitalizations have been reported from 3 provinces (AB, ON & NL); all were ≥ 65 years of age. Of the influenza A hospitalizations where subtype was available (4), 50% were due to influenza A(H1N1)pdm09 and 50% were due to A(H3N2). There has been one hospitalisation for which admission to ICU was required (from NL). To date this season, no influenza-associated deaths have been reported.

Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #6 November 2nd, 2012, 05:20 PM

Fluwatch Report: October 21 to October 27, 2012 (Week 43)

Posted 2012-11-02For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: October 21 to October 27, 2012 (Week 43) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

Influenza activity in Canada remains low and was similar to the previous week
In week 43, a total of 25 laboratory detections of influenza were reported, 88% of which were for influenza A viruses (68.2% A(H3) and 31.8% A(un-subtyped)).
Two influenza outbreaks in long-term care facilities were reported in week 43
Five influenza A-associated hospitalizations (in persons ≥65 years of age) were reported in week 43
The ILI consultation rate increased in week 43 to 20.0 per 1,000 patient visits but is within the expected level for this time of year

Influenza Activity (geographic spread) and Outbreaks

In week 43, 4 regions (within AB(1) & ON(3)) reported localized activity, 5 regions (within BC, AB(2), ON & QC) reported sporadic activity and the rest reported no activity (see Figure 1). Two new influenza outbreaks were reported in week 43 (in AB & ON) and both were in long-term care facilities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 43

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased slightly from the previous week from 0.9% in week 42 to 1.3% in week 43 (Figure 4 and link to figure 55). Among the influenza viruses detected this week (n=25), 88% were positive for influenza A viruses (of which 68.2% were A(H3) and 31.8% were A unsubtyped) and 12% for influenza B viruses (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 92.1% influenza A (58.1% - A(H3), 7.5% - A(H1N1)pdm09 and 34.4% - unsubtyped) and 7.9% influenza B (Table 1).
Detailed information on age and type/subtype were received on 79 cases to date this season (Table 2). The proportions of cases by age group were as follows: 11.4% were < 5 years; 6.3% were between 5-19 years; 15.2% were between 20-44 years; 16.5% were between 45-64 years of age; 50.6% were ≥ 65 years.
The percentage positive for rhinovirus detections decreased from the previous week, from 24.9% in week 42 to 19.4% week 43, and remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 43 remained low: RSV 2.0%; parainfluenza 3.0%; adenovirus 2.0%; hMPV 0.6%; and coronavirus 0.7% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (October 21 to October 27, 2012)						Cumulative (August 26, 2012 to October 27, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	0	0	0	0	0	1	6	0	4	0	2	1
AB	7	0	6	0	1	1	32	0	19	7	6	2
SK	0	0	0	0	0	0	2	0	0	0	2	1
MB	0	0	0	0	0	0	3	0	3	0	0	0
ON	14	0	9	0	5	1	42	0	27	0	15	2
QC	1	0	0	0	1	0	6	0	0	0	6	2
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	0	0	0	0	0	0	2	0	1	0	1	0
Canada	22	0	15	0	7	3	93	0	54	7	32	8

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (October 21 to October 27, 2012)					Cumulative (August 26, 2012 to October 27, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	1	0	1	0	1	7	1	6	0	2
5-19	1	0	1	0	0	5	0	4	1	0
20-44	0	0	0	0	1	11	3	4	4	1
45-64	3	0	1	2	0	10	1	4	5	3
65+	10	0	4	6	0	39	2	22	15	1
Unknown	0	0	0	0	0	0	0	0	0	0
Total	15	0	7	8	2	72	7	40	25	7

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 3 influenza viruses [1 A(H3N2) and 2 B]. The influenza A(H3N2) virus (from BC) was antigenically similar to the vaccine strain A/Victoria/361/2011. Both of the influenza B viruses (from ON & QC) were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 3

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 3 influenza viruses [1 A(H3N2) and 2 B] for resistance to oseltamivir and zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 6 influenza A(H3N2) viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	1	0	1	0	6	6 (100%)
A (H1N1)	0	0	0	0	0	0
B	2	0	2	0	NA ^*	NA ^*
TOTAL	3	0	3	0	6	6 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 43 increased from the previous week from 17.8 to 20.0 ILI consultations per 1,000 patient visits and is within the expected levels for this time of year (Figure 7). The highest consultation rates were observed in those less than 5 years of age (34.8/1,000) and those ≥65 years of age (23.6/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
No laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations have been reported by the Immunization Monitoring Program Active (IMPACT) network since the start of the 2012-2013 influenza season.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)
In week 43, five laboratory-confirmed influenza A-associated hospitalizations were reported [from ON(4) & AB(1)]. The cases were all ≥65 years of age.

To date this season, 11 influenza A-associated hospitalizations have been reported from 3 provinces (AB, ON & NL); all were ≥ 65 years of age. Of the influenza A hospitalizations where subtype was available, 22.2% (2) were due to influenza A(H1N1)pdm09 and 77.8% (7) were due to A(H3N2).

There has been one hospitalisation for which admission to ICU was required (from NL). To date this season, no influenza-associated deaths have been reported.

Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, & NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #7 November 9th, 2012, 05:08 PM

Fluwatch Report: October 28 to November 3, 2012 (Week 44)

Posted 2012-11-09For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: October 28 to November 3, 2012 (Week 44) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

Influenza activity in Canada increased slightly compared to the previous week; however overall activity still remains fairly low, with most regions of the country reporting no activity.
In week 44, a total of 64 laboratory detections of influenza were reported; of which 91% were for influenza A viruses [71% A(H3) and 29% A(un-subtyped)].
Six influenza outbreaks in long-term care facilities were reported in week 44.
Eleven influenza A-associated hospitalizations were reported in week 44: 8 in adults >20 years of age, and 2 in children.
The ILI consultation rate increased in week 44 to 21.9 per 1,000 patient visits but is within the expected level for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 44, 5 regions [within AB(1), SK(1), ON(2) and QC(1)] reported localized activity, 9 regions [within BC(1), AB(2), MB(1), ON(1), QC(3) and PE(1)] reported sporadic activity and the rest reported no activity (Figures 1 and 2). Six new influenza outbreaks were reported in week 44 [in AB(2), SK(1), ON(2) and QC(1)] and all were in long-term care facilities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 44

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from the previous week, from 1.3% in week 43 to 2.8% in week 44 (Figures 4 and 5). Among the influenza viruses detected this week (n=64), 90.6% were positive for influenza A viruses [of which 70.7% were A(H3) and 29.3% were A unsubtyped] and 9.4% for influenza B viruses (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 91.6% influenza A [64.5% A(H3), 4.6% A(H1N1)pdm09 and 30.9% A(unsubtyped)] and 8.4% influenza B (Table 1).
Detailed information on age and type/subtype was received for 104 cases to date this season (Table 2).The proportions of cases by age group were as follows: 8.7% were < 5 years; 8.7% were between 5-19 years; 13.5% were between 20-44 years; 15.4% were between 45-64 years of age; 53.9% were ≥ 65 years.
The percentage positive for rhinovirus detections decreased from the previous week, from 20.6% in week 43 to 15.5% week 44; but remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 44 remained low, although RSV and parainfluenza increased slightly compared to week 43: RSV 2.4%; parainfluenza 3.3%; adenovirus 1.1%; hMPV 0.2%; and coronavirus 1.3% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (October 28 to November 3, 2012)						Cumulative (August 26, 2012 to November 3, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	1	0	0	0	1	2	7	0	4	0	3	3
AB	28	0	24	0	4	0	60	0	44	7	9	2
SK	1	0	0	0	1	0	3	0	0	0	3	1
MB	1	0	0	0	1	0	4	0	3	0	1	0
ON	17	0	12	0	5	1	59	0	39	0	20	3
QC	9	0	4	0	5	3	16	0	5	0	11	5
NB	0	0	0	0	0	0	0	0	0	0	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	1	0	1	0	0	0	1	0	1	0	0	0
NL	0	0	0	0	0	0	2	0	2	0	0	0
Canada	58	0	41	0	17	6	152	0	98	7	47	14

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (October 28 to November 3, 2012)					Cumulative (August 26, 2012 to November 3, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	0	0	0	0	0	7	1	6	0	2
5-19	4	0	2	2	0	9	0	6	3	0
20-44	2	0	2	0	0	13	3	6	4	1
45-64	3	0	2	1	0	13	1	6	6	3
65+	16	0	15	1	0	55	2	37	16	1
Unknown	0	0	0	0	0	0	0	0	0	0
Total	25	0	21	4	0	97	7	61	29	7

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 6 influenza viruses [4 A(H3N2) and 2 B]. The 4 influenza A(H3N2) viruses (from BC and ON) were antigenically similar to the vaccine strain A/Victoria/361/2011. Both of the influenza B viruses (from ON and QC) were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 6

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 6 influenza viruses [4 A(H3N2) and 2 B] for resistance to oseltamivir and zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 14 influenza A(H3N2) viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	4	0	4	0	14	14 (100%)
A (H1N1)	0	0	0	0	0	0
B	2	0	2	0	NA ^*	NA ^*
TOTAL	6	0	6	0	14	14 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 44 increased from the previous week from 19.6 to 21.9 ILI consultations per 1,000 patient visits; but remains within the expected levels for this time of year (Figure 7). The highest consultation rates were observed in children less than 5 years of age (80.1/1,000) and children 5-19 years of age (37.4/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
Since the start of the 2012-13 season, one laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalization has been reported by the Immunization Monitoring Program Active (IMPACT) network. The hospitalization was reported in Saskatchewan in week 42, in a child between 10 and 16 years of age with influenza A.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)

In week 44, 11 laboratory-confirmed influenza A-associated hospitalizations were reported [ON(5), MB(1), AB(5)]. Of these, eight were aged ≥65 years, one between 45-64 years, one between 5-9 years and one < 1 year. Among the 11 influenza A hospitalizations, nine were Influenza A/H3N2 and two were unsubtyped. None of these cases were admitted to the Intensive Care Unit (ICU), and there were no deaths.

To date this season, 27 influenza A-associated hospitalizations have been reported from four provinces (AB, MB, ON and NL). The majority of the cases (81.5%; 22/27) were ≥ 65 years of age. Of the influenza A hospitalizations for which subtype was available, 13.0% (3/23) were due to influenza A(H1N1)pdm09 and 87.0% (20/23) were due to A(H3N2).

There have been three hospitalizations for which admission to ICU was required (from NL and AB). To date this season, no influenza-associated deaths have been reported.

Note: Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #8 November 16th, 2012, 04:52 PM

Fluwatch Report: November 4 to November 10, 2012 (Week 45)

Posted 2012-11-16For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: November 4 to November 10, 2012 (Week 45) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

Influenza activity in Canada increased compared to the previous week with more regions reporting increased activity, particularly in Ontario; however overall activity in Canada still remains relatively low, with the majority of regions of the country reporting no activity.
In week 45, a total of 106 laboratory detections of influenza were reported, of which 92.5% were for influenza A viruses, predominantly A(H3N2).
Eight influenza outbreaks were reported in week 45: 5 in long-term care facilities and 3 in other settings.
One influenza-associated hospitalization was reported through the IMPACT network, with influenza A from BC, and 16 influenza-associated hospitalizations in adults ≥20 years of age were reported through Aggregate surveillance.
The ILI consultation rate decreased slightly in week 45 but is within the expected level for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 45, 1 region [in ON] reported widespread activity, 3 regions [in AB(1), and ON(2)] reported localized activity, 13 regions [in BC(2), AB(2), MB(1), ON(3), QC(4) and NB(1)] reported sporadic activity and the rest reported no activity (Figures 1 and 2). Eight new influenza outbreaks were reported in week 45: 5 in long-term care facilities [in AB(3) and ON(2)] and 3 in other settings [in ON ] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 45

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from the previous week, from 2.8% in week 44 to 5.0% in week 45 (Figure 4 and link to figure 55). Among the influenza viruses detected this week (n=106), 92.5% were positive for influenza A viruses [of which 61.2% were A(H3), 6.1% were A(H1N1)pdm09, and 32.7% were A unsubtyped] and 7.5% for influenza B viruses (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 91.9% influenza A [65.7% A(H3), 5.6% A(H1N1)pdm09 and 28.7% A(unsubtyped)] and 8.1% influenza B (Table 1).
Detailed information on age and type/subtype was received for 168 cases to date this season (Table 2). The proportions of cases by age group were as follows: 13.7% were < 5 years; 8.3% were between 5-19 years; 14.3% were between 20-44 years; 15.5% were between 45-64 years of age; 48.2% were ≥ 65 years.
The percentage positive for rhinovirus detections increased slightly from the previous week, from 17.1% in week 44 to 19.1% week 45; and remains the highest compared to the other respiratory viruses. The percentage positive for the other respiratory viruses in week 45 remained low, although several increased slightly compared to week 44: RSV 4.1%; parainfluenza 3.9%; adenovirus 2.3%; hMPV 0.2%; and coronavirus 2.3% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (November 4 to November 10, 2012)						Cumulative (August 26, 2012 to November 10, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	3	0	3	0	0	1	10	0	7	0	3	4
AB	38	0	31	1	6	1	99	0	80	8	11	3
SK	1	0	1	0	0	0	4	0	1	0	3	1
MB	3	0	3	0	0	1	7	0	6	0	1	1
ON	28	0	22	4	2	3	87	0	63	5	19	6
QC	24	0	0	0	24	2	41	0	6	0	35	7
NB	1	0	0	1	0	0	1	0	0	1	0	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	0	0	0	0	0	0	0	0	0	0	0	0
NL	0	0	0	0	0	0	2	0	2	0	0	0
Canada	98	0	60	6	32	8	251	0	165	14	72	22

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (November 4 to November 10, 2012)					Cumulative (August 26, 2012 to November 10, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	4	1	2	1	0	19	2	14	3	4
5-19	1	0	1	0	1	13	0	9	4	1
20-44	4	1	2	1	0	23	5	12	6	1
45-64	1	0	1	0	0	22	1	16	5	4
65+	8	0	8	0	0	78	2	59	17	3
Unknown	0	0	0	0	0	0	0	0	0	0
Total	18	2	14	2	1	155	10	110	35	13

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 9 influenza viruses [7 A(H3N2) and 2 B]. The 7 influenza A(H3N2) viruses (from BC, ON and QC) were antigenically similar to the vaccine strain A/Victoria/361/2011. Both of the influenza B viruses (from ON and QC) were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 9

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 9 influenza viruses [7 A(H3N2) and 2 B] for resistance to oseltamivir and zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 21 influenza A(H3N2) viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	7	0	7	0	21	21 (100%)
A (H1N1)	0	0	0	0	0	0
B	2	0	2	0	NA ^*	NA ^*
TOTAL	9	0	9	0	21	21 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 45 decreased from the previous week from 22.2 to 19.1 ILI consultations per 1,000 patient visits; but remains within the expected levels for this time of year (Figure 7). The highest consultation rates were observed in children 5-19 years of age (31.3/1,000) and adults 20-64 years of age (17.6/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 45, one new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalization was reported by the Immunization Monitoring Program Active (IMPACT) network. The case was reported in BC, in a child 10-16 years of age with unsubtyped influenza A.

Since the start of the 2012-13 season, a total of three laboratory-confirmed influenza-associated paediatric hospitalizations have been reported by the IMPACT network. Two cases were between 10-16 years of age, and one between 5-9 years of age. In all three cases, influenza A was detected [two A(H3N2), one influenza A(unsubtyped)]. One case is reported to have had underlying conditions, and this case was admitted to the ICU.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 45, 20 laboratory-confirmed influenza A-associated hospitalizations were reported [ON(9), AB(11)]. Of these, 4 were aged between 1-4 years, 1 between 20-44 years, 2 between 45-64 years, and 13 were aged ≥65 years. Of these hospitalizations, 15 were due to Influenza A(H3N2) and five were due to influenza A (unsubtyped). No deaths were reported this week. Of the 11 cases with available data, none were admitted to the Intensive Care Unit (ICU).

To date this season, 49 influenza A-associated hospitalizations have been reported from four provinces (AB, MB, ON & NL). The majority of the cases (75.5%; 37/49) were ≥ 65 years of age. Of the influenza A hospitalizations for which subtype was available (n=40), 7.5% (3/40) were due to influenza A(H1N1)pdm09 and 92.5% (37/40) were due to A(H3). Of the 29 cases with available data, there have been four hospitalizations for which admission to ICU was required (from NL and AB). To date this season, one influenza A(H3)-associated death has been reported (week 36) in a hospitalized case who was ≥ 65 years of age.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #9 November 23rd, 2012, 06:53 PM

Fluwatch Report: November 11 to November 17, 2012 (Week 46)

Posted 2012-11-23For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: November 11 to November 17, 2012 (Week 46) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada increased compared to the previous week with more regions reporting sporadic and localized activity.
In week 46, a total of 151 laboratory detections of influenza were reported, of which 93.4% were for influenza A viruses, predominantly A(H3N2).
Nine influenza outbreaks were reported in week 46: 6 in long-term care facilities and 3 in other settings.
Three paediatric influenza-associated hospitalizations were reported this week through the IMPACT network, and 15 cases in adults ≥20 years of age were reported through Aggregate surveillance.
The ILI consultation rate increased compared to the previous week but remains within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 46, 8 regions [in BC(1), AB(2) and ON(5)] reported localized activity, 16 regions [in BC(3), AB(2), SK(2), MB(1), ON(1), QC(5), PE(1) and NL(1)] reported sporadic activity and the rest reported no activity. No report was received from Nunavut (Figures 1 and 2). Nine new influenza outbreaks were reported in week 46: 6 in long-term care facilities [in BC(1), AB(1) and ON(4)] and 3 in other settings [in AB(1) and ON(2)] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 46

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from the previous week, from 4.5% in week 45 to 6.0% in week 46 (Figure 4 and link to figure 55). Among the influenza viruses detected this week (n=151), 93.4% were positive for influenza A viruses [of which 60.3% were A(H3), 3.5% were A(H1N1)pdm09, and 36.2% were A unsubtyped] and 6.6% for influenza B viruses (Table 1).
Cumulative influenza virus detections by type/subtype to date are as follows: 92.6% influenza A [64.3% A(H3), 5.0% A(H1N1)pdm09 and 30.7% A(unsubtyped)] and 7.4% influenza B (Table 1).
Detailed information on age and type/subtype was received for 369 cases to date this season (Table 2). The proportions of cases by age group were as follows: 16.0% were < 5 years; 10.8% were between 5-19 years; 16.0% were between 20-44 years; 18.2% were between 45-64 years of age; 39.0% were ≥ 65 years.
The percentage positive for rhinovirus detections decreased from the previous week, from 17.6% in week 45 to 15.1% week 46, but remains the highest compared to the other respiratory viruses. The percentage positive for RSV (5.3%), parainfluenza (5.1%) and coronavirus (3.5%) detections increased slightly compared to the previous week, while other percentages remained low: adenovirus 1.7%; hMPV 0.6% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (November 11 to November 17, 2012)						Cumulative (August 26, 2012 to November 17, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	13	0	13	0	0	2	23	0	20	0	3	6
AB	27	0	18	2	7	5	126	0	98	11	17	8
SK	7	0	6	0	1	0	11	0	7	0	4	1
MB	2	0	2	0	0	0	9	0	8	0	1	1
ON	56	0	45	3	8	2	149	0	114	8	27	8
QC	33	0	0	0	33	1	74	0	6	0	68	8
NB	1	0	0	0	1	0	2	0	0	1	1	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	1	0	1	0	0	0	1	0	1	0	0	0
NL	1	0	0	0	1	0	3	0	2	0	1	0
Canada	141	0	85	5	51	10	398	0	256	20	122	32

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (November 11 to November 17, 2012)					Cumulative (August 26, 2012 to November 17, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	18	1	9	8	0	54	4	34	16	5
5-19	9	0	6	3	2	36	0	29	7	4
20-44	16	0	13	3	0	57	6	38	13	2
45-64	11	2	4	5	4	56	4	37	15	11
65+	24	1	12	11	0	141	3	93	45	3
Unknown	1	0	1	0	0	1	0	1	0	0
Total	79	4	45	30	6	345	17	232	96	25

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 20 influenza viruses [12 A(H3N2), 3 A(H1N1)pdm09 , and 5 influenza B]. The 12 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 3 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 4 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and one was similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 20

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 20 influenza viruses [12 A(H3N2), 3 A(H1N1)pdm09 and 5 B] for resistance to oseltamivir and zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 36 influenza A [35 A(H3N2) and 1 A(H1N1)pdm09] viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	12	0	12	0	35	35 (100%)
A (H1N1)	3	0	3	0	1	1
B	5	0	5	0	NA ^*	NA ^*
TOTAL	20	0	20	0	36	36 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 46 increased from the previous week from 18.0 to 27.2 ILI consultations per 1,000 patient visits; but remains within the expected levels for this time of year (Figure 7). The highest consultation rates were observed in children 5-19 years of age (79.2/1,000) followed by children <5 years of age (67.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate has been increasing gradually since early October, 2012, from a rate of 10.3 antiviral prescriptions per 100,000 new prescriptions dispensed in week 41 to 17.2/100,000 in week 46. Based on retrospective data available since April 2011, antiviral prescription rates observed during interseasonal periods normally ranged from 4-11/100,000 while rates between 12-24/100,000 were observed during periods of low influenza virus circulation overall. In week 46, the highest rate was observed for children 2-17 years of age (26.6/100,000). Regionally, only the antiviral prescription rates for Ontario and British Columbia have shown a steady increase since early October.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 46, 3 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Two cases were reported from AB: one child <5 years of age with A(H3N2), and another 10-6 years of age with unsubtyped influenza A. One case was reported from QC in a child 2-4 years of age with unsubtyped influenza A, admitted to the Intensive Care Unit (ICU).

Since the start of the 2012-13 season, a total of 7 influenza-associated paediatric hospitalizations have been reported by the IMPACT network, all with influenza A. The number of cases by age group is as follows: one <5 years of age, one age 2-4 years, one age 5-9 years, and four 10-16 years. Two of the seven cases (28.6%) were admitted to the ICU.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 46, 19 laboratory confirmed influenza-associated hospitalizations were reported [ON(11), AB(4), MB(3), NL(1)]. The age breakdown was as follows: one aged between 1-4 years, one between 5-9 years, two between 15-19 years, two between 20-44 years, five 45-64 and eight were aged ≥65 years. Of these 19 influenza hospitalizations, 16 were influenza A [6 A(H3N2), 2 A(H1N1)pdm09, 8 A(unsubtyped)] and three were influenza B. Of the 8 cases with available data, 2 cases were admitted to the Intensive Care Unit (ICU): one case of Influenza A(H3) in a child aged between 5-9 years, and the second in a case of influenza B in an adult aged 45-64 years. There were no deaths.

To date this season, 68 influenza-associated hospitalizations have been reported from four provinces (AB, MB, ON & NL). The majority of cases have been influenza A (95.6%; 65/68). Two thirds of the cases (66.2%; 45/68) were ≥ 65 years of age. Of the 49 influenza A hospitalizations for which subtype was available, 12.2% (6/49) were due to influenza A(H1N1)pdm09 and 87.8% (43/49) were due to A(H3N2). Among the 37 cases with available data, there have been 6 hospitalizations for which admission to ICU was required (from NL and AB). To date this season, one influenza-associated death was reported (week 36) in a hospitalized Influenza A(H3) case who was aged ≥65 years.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #10 November 30th, 2012, 05:45 PM

Fluwatch Report: November 18 to November 24, 2012 (Week 47)

Posted 2012-11-30For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: November 18 to November 24, 2012 (Week 47) (PDF Version - 113 KB - 6 pages)

»» Help with PDF documents

Overall Influenza Summary

The influenza season has started in Canada with increases in all influenza indicators observed this week.
More regions reported sporadic or localized activity compared to the previous week.
A total of 278 laboratory detections of influenza were reported, of which 97.8% were for influenza A viruses, predominantly A(H3N2).
Eight influenza outbreaks were reported: one in a hospital, five in long-term care facilities and two in other settings.
Seven paediatric influenza-associated hospitalizations were reported through the IMPACT network, and 27 cases in adults ≥20 years of age were reported through Aggregate surveillance.
The ILI consultation rate increased compared to the previous week but is within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 47, seven regions [in BC(1), AB(1), SK(1) and ON(4)] reported localized activity, 21 regions [in BC(2), AB(4), SK(2), MB(1), ON(3), QC(6), NB(1), PE(1) and YK(1)] reported sporadic activity and the rest reported no activity (Figures 1 and 2). Eight new influenza outbreaks were reported in week 47: one in a hospital [in ON], five in long-term care facilities [in BC(1), AB(1), SK(1) and ON(2)] and two in other settings [in ON] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 47

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from the previous week, from 5.9% in week 46 to 9.6% in week 47 (Figure 4). Among the influenza viruses detected this week (n=278), 97.8% were positive for influenza A viruses [of which 55.9% were A(H3), 1.1% were A(H1N1)pdm09, and 43.0% were A unsubtyped]; 2.2% of viruses detected were influenza B viruses (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 94.6% influenza A [61.8% A(H3), 3.4% A(H1N1)pdm09 and 34.8% A(unsubtyped)] and 5.4% influenza B (Table 1).
Detailed information on age and type/subtype was received for 625 cases to date this season (Table 2). The proportions of cases by age group were as follows: 13.3% were < 5 years; 12.8% were between 5-19 years; 16.8% were between 20-44 years; 16.8% were between 45-64 years of age; 40.3% were ≥ 65 years.
The percentage positive for rhinovirus detections continued to decline in week 47 to 15.3%, but remains the highest compared to the other respiratory viruses. The percentage positive for RSV (5.7%) increased compared to the previous week, while parainfluenza (4.4%) and coronavirus (3.1%) detections declined slightly. Other percentages of positive tests remained low: adenovirus 2.1%; hMPV 0.9% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
Reporting provinces	Weekly (November 18 to November 24, 2012)						Cumulative (August 26, 2012 to November 24, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	30	0	24	0	6	0	53	0	44	0	9	6
AB	39	0	24	0	15	1	165	0	129	11	25	9
SK	13	0	11	0	2	2	24	0	18	0	6	3
MB	3	0	3	0	0	1	12	0	11	0	1	2
ON	109	0	89	3	17	0	260	0	203	11	46	8
QC	77	0	0	0	77	2	151	0	6	0	145	10
NB	0	0	0	0	0	0	2	0	0	1	1	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	1	0	1	0	0	0	2	0	2	0	0	0
NL	0	0	0	0	0	0	3	0	2	0	1	0
Canada	272	0	152	3	117	6	672	0	415	23	234	38

Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
Age groups	Weekly (November 18 to November 24, 2012)					Cumulative (August 26, 2012 to November 24, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	14	0	5	9	0	77	4	47	26	6
5-19	22	0	12	10	1	74	0	55	19	6
20-44	30	1	15	14	1	101	7	67	27	4
45-64	21	0	7	14	1	91	5	55	31	14
65+	73	0	33	40	0	249	4	150	95	3
Unknown	1	0	1	0	0	2	0	2	0	0
Total	161	1	73	87	3	594	20	376	198	33

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 35 influenza viruses [22 A(H3N2), 4 A(H1N1)pdm09 , and 9 influenza B]. The 22 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 4 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 7 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 2 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 35

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 31 influenza viruses [19 A(H3N2), 4 A(H1N1)pdm09 and 8 B] for resistance to oseltamivir and has tested 30 influenza viruses [18 A(H3N2), 4 A(H1N1)pdm09 and 8 B] for resistance to zanamivir and it was found that all were sensitive to oseltamivir and zanamivir. A total of 49 influenza A viruses [46 A(H3N2) and 3 A(H1N1)pdm09] were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	19	0	18	0	46	46 (100%)
A (H1N1)	4	0	4	0	3	3
B	8	0	8	0	NA ^*	NA ^*
TOTAL	31	0	30	0	49	49 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 47 increased from the previous week from 21.3 to 28.6 ILI consultations per 1,000 patient visits which is within the expected level for this time of year (Figure 7). The highest consultation rates were observed in children 5-19 years of age (69.1/1,000) followed by children <5 years of age (20.3/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

Following a gradual increase since early October 2012 (week 40), the Canadian antiviral prescription rate jumped from a rate of 17.3 antiviral prescriptions per 100,000 new prescriptions dispensed in week 46 to 47.7/100,000 in week 47, due in large part to increases in antiviral prescriptions reported from BC, AB, ON and QC. Based on data collected since April 2011, the current rate of antiviral prescriptions of 47.7/100,000 is higher than expected based on the current percentage of positive laboratory tests for influenza, and closer to the rate observed when the percentage of influenza detections was between 10%-15%. In week 47, the antiviral prescription rates increased for all age groups; however the highest rate, and highest rate of increase, was observed in seniors >75 years of age (120.6/100,000).
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 47, seven new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Five cases were reported with unsubtyped influenza A [from ON(1) and QC(4)], one with A(H3N2) [from AB], and one with influenza B [from SK]. One case in QC was admitted to the ICU. Two of the seven cases were under 6 months of age, two were between 6-23 months, two age 2-4 years, and one age 5-9 years.
Since the start of the 2012-13 season, a total of 20 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 18 (90%) with influenza A [of which 6 (33%) were A(H3N2) and 12 (67%) were unsubtyped], and 2 (10%) with influenza B. The distribution of cases by age group is as follows: 4 (20%) <6 months of age, 3 (15%) age 6-23 months, 6 (30%) age 2-4 years, 3 (15%) age 5-9 years, and 4 (20%) age 10-16 years. Three of the 20 cases (15%) were admitted to the ICU.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 47, 36 laboratory confirmed influenza A-associated hospitalizations were reported [AB(13), MB(2), ON(20), PE(1)]. The age group most affected was ≥ 65 years of age (15/36; 41.7%). Of these 36 influenza hospitalizations, 35 were influenza A [A(H1N1)pdm09(3), A(H3)(18), A(unsubtyped)(14)] and one was influenza B. Of the 16 cases with available data, one case of influenza A(H3) in a person aged between 20-44years was admitted to the Intensive Care Unit (ICU). There were 3 deaths, all in influenza A cases in persons ≥ 65 years of age. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. No report was received from YT this week.

To date this season, 103 influenza-associated hospitalizations have been reported from five provinces (AB, MB, NL,ON and PEI). The majority of cases have been influenza A (99/103; 96.1%). More than half of the cases (60/103; 58.2%) were ≥ 65 years of age. Of the influenza A hospitalizations for which subtype was available (n=71), 12.7% (9/71) were due to influenza A(H1N1)pdm09, and 87.3% (62/71) were due to A(H3). Among the 52 cases with available data, there have been 8 hospitalisations for which admission to ICU was required, half of which were persons ≥ 65 years of age. To date this season, four deaths have been reported: all in influenza A cases (3 H3; 1 unsubtyped) aged 65 years or older. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #11 December 7th, 2012, 05:15 PM

Fluwatch Report: November 25 to December 1, 2012 (Week 48)

Posted 2012-12-07For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: November 25 to December 1, 2012 (Week 48) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada continued to increase in week 48.
More regions reported sporadic activity compared to the previous week.
A total of 414 laboratory detections of influenza were reported, of which 97.3% were for influenza A viruses, predominantly A(H3N2).
Eleven influenza outbreaks were reported, all in long-term-care facilities.
Eight paediatric influenza-associated hospitalizations were reported through the IMPACT network, and six hospitalizations in adults ≥20 years of age were reported through Aggregate surveillance.
The ILI consultation rate increased compared to the previous week and is above the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 48, 13 regions [in BC(1), AB(2), SK(2), ON(6), and QC(2)] reported localized activity, 16 regions [in BC(3), AB(3), SK(1), MB(1), ON(1), QC(4), NB(1), PE(1), and YK(1)] reported sporadic activity and the rest reported no activity (Figures 1 and 2). Eleven new influenza outbreaks were reported in week 48: all in long-term-care facilities [in BC(1), AB(3), ON(5), and QC(2)] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 48

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from 9.5% in week 47 to 11.7% in week 48 (Figure 4). Among the influenza viruses detected this week (n=414), 97.3% were positive for influenza A viruses [of which 53.8% were A(H3), 1.0% were A(H1N1)pdm09, and 45.2% were A(unsubtyped)]; and 2.7% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 95.7% influenza A [61.0% A(H3), 2.5% A(H1N1)pdm09 and 36.5% A(unsubtyped)] and 4.3% influenza B (Table 1).
Detailed information on age and type/subtype was received for 929 cases to date this season (Table 2). The proportions of cases by age group were as follows: 13.0% were < 5 years; 11.6% were between 5-19 years; 18.0% were between 20-44 years; 16.6% were between 45-64 years of age; 40.8% were ≥ 65 years.
The percentage of tests positive for rhinovirus detections continued to decline in week 48 to 10.9%, and is now below the percentage positive for influenza. The percentage positive for RSV (6.7%) increased compared to the previous week. Parainfluenza (4.3%) detections were stable and coronavirus (3.1%) detections increased slightly. Other percentages of positive tests remained low: adenovirus 1.5%; hMPV 0.6% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (November 25 to December 1, 2012)						Cumulative (August 26, 2012 to December 1, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	18	0	16	1	1	2	71	0	64	1	6	8
AB	66	0	51	0	15	1	234	0	197	11	26	10
SK	38	0	35	0	3	3	62	0	53	0	9	6
MB	2	0	2	0	0	1	14	0	13	0	1	3
ON	149	0	111	3	35	2	412	0	320	14	78	10
QC	128	0	0	0	128	2	279	0	6	0	273	12
NB	1	0	1	0	0	0	3	0	1	1	1	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	1	0	1	0	0	0	3	0	3	0	0	0
NL	0	0	0	0	0	0	3	0	2	0	1	0
Canada	403	0	217	4	182	11	1081	0	659	27	395	49

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (November 25 to December 1, 2012)					Cumulative (August 26, 2012 to December 1, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
< 5	20	0	6	14	0	115	5	68	42	6
5-19	13	0	6	7	1	100	0	73	27	8
20-44	30	1	12	17	3	160	9	101	50	7
45-64	32	0	14	18	0	140	5	83	52	14
65+	85	0	32	53	0	376	4	219	153	3
Unknown	1	0	1	0	0	3	0	3	0	0
Total	181	1	71	109	4	894	23	547	324	38

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 49 influenza viruses [33 A(H3N2), 6 A(H1N1)pdm09 , and 10 influenza B]. The 33 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The six A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, seven were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and three were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 49

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 45 influenza viruses [28 A(H3N2), 7 A(H1N1)pdm09 and 10 B] for resistance to oseltamivir, and 44 influenza viruses [27 A(H3N2), 7 A(H1N1)pdm09 and 10 B] for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 78 influenza A viruses [72 A(H3N2) and 6 A(H1N1)pdm09] were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	28	0	27	0	72	72 (100%)
A (H1N1)	7	0	7	0	6	6
B	10	0	10	0	NA ^*	NA ^*
TOTAL	45	0	44	0	78	78 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 48 increased from the previous week: from 25.1 to 39.8 ILI consultations per 1,000 patient visits, which is above the expected level for this time of year (Figure 7). The highest consultation rates were observed in children 5-19 years of age (102.2/1,000) followed by children <5 years of age (62.5/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

Following the sharp increase in the Canadian antiviral prescription rate to 47.8 antiviral prescriptions per 100,000 new prescriptions dispensed in week 47, the rate continued to increase to 58.6 in week 48, due to increases in antiviral prescriptions reported from BC, AB, ON and SK. The current rate of 58.6/100,000 is higher than expected based on the current percentage of positive laboratory tests for influenza, and closer to the rate observed when the percentage of influenza detections was between 15%-18% (data from April 2011 to present). In week 48, the antiviral prescription rates increased for all age groups except among seniors (≥75 years), however, the rate among seniors remained the highest of all the age groups in week 48( 97.0/100,000).
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 48, eight new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network. Six cases were reported with unsubtyped influenza A [from QC(5) and MB(1)], and two with A(H3N2) [from AB]. One case in QC between 10-16 years of age was admitted to the ICU. The age distribution of hospitalized cases is a follows: one under 6 months of age, two between 6-23 months, three aged 2-4 years, and two aged 10-16 years.

Since the start of the 2012-13 season, a total of 27 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 25 (92.3%) with influenza A [of which 8 (32%) were A(H3N2) and 17 (68%) were unsubtyped], and two (7.7%) with influenza B. The distribution of cases by age group is as follows: 5 (18.5%) <6 months of age, 4 (14.8%) age 6-23 months, 8 (29.6%) age 2-4 years, 4 (14.8%) age 5-9 years, and 6 (22.2%) age 10-16 years. Five of the 27 cases (18.5%) were admitted to the ICU.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 48, 11 laboratory confirmed influenza-associated hospitalizations were reported [AB(8), ON(3)]. Of these, five were in children aged 0-4 years, three in adults over 65 years of age, and three in adults aged 45-64 years. Eight of the 11 hospitalizations were influenza A(H3) and three were A(unsubtyped). Of the 8 cases with available data, two cases of influenza A(unsubtyped) were admitted to the Intensive Care Unit (ICU): one adult aged 46-64 years, and one adult aged 65+. There was one death in influenza A case aged ≥ 65 years. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting.

To date this season, 114 influenza-associated hospitalizations have been reported from five provinces (AB, MB, NL, ON and PE). The majority of cases have been influenza A (96.5%, 110/114). More than half of the cases (55.2%, 63/114) are ≥ 65 years of age. Of the 85 influenza A hospitalizations for which subtype was available, 10.6% (9/85) were due to influenza A(H1N1)pdm09, and 84.7% (72/85) were due to A(H3). Among the 60 cases with available data, there have been 10 hospitalizations for which admission to ICU was required, half of which were persons ≥ 65 years of age. To date this season, six deaths have been reported: all in influenza A cases (4 H3; 2 unsubtyped) aged 65 years or older. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #12 December 14th, 2012, 04:22 PM

Fluwatch Report: December 2 to December 8, 2012 (Week 49)

Posted 2012-12-14For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: December 2 to December 8, 2012 (Week 49) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada continued to increase in week 49; one region reported widespread activity, and more regions reported sporadic or localized activity.
A total of 816 laboratory detections of influenza were reported, of which 96.4% were for influenza A viruses, predominantly A(H3N2).
Twenty-two influenza outbreaks were reported: 12 in long-term-care facilities, 5 in schools and 5 in other facilities.
Twenty-five paediatric influenza-associated hospitalizations were reported through the IMPACT network, all but one with influenza A
Eighty-seven hospitalizations and 8 deaths in adults ≥20 years of age were reported through Aggregate surveillance, all but two with influenza A.
The ILI consultation rate decreased compared to the previous week and is within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 49, one region [in ON] reported widespread influenza activity, 13 regions [in BC(2), AB(2), SK(1), ON(4), QC(2), NB(1) and NL(1)] reported localized activity, 21 regions [in BC(3), AB(3), SK(2), MB(2), ON(2), QC(4), NB(3), PE(1), and YK(1)] reported sporadic activity and the rest reported no activity (Figures 1 and 2). Twenty-two new influenza outbreaks were reported in week 49: 12 in long-term-care facilities [in BC(2), AB(1), SK(2), ON(5), and QC(2)], five in schools [in BC(2), AB(2) and NB(1)], and 5 in other facilities [in ON(4) and NL(1)] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 49

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from 11.7% in week 48 to 17.8% in week 49 (Figure 4). Among the influenza viruses detected this week (n=816), 96.4% were positive for influenza A viruses [of which 46.3% were A(H3), 1.8% were A(H1N1)pdm09, and 52.0% were A(unsubtyped)]; and 3.6% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 96.0% influenza A [55.7% A(H3), 2.1% A(H1N1)pdm09 and 42.2% A(unsubtyped)] and 4.0% influenza B (Table 1).
Detailed information on age and type/subtype was received for 1731 cases to date this season (Table 2). The proportions of cases by age group were as follows: 14.4% were < 5 years; 12.1% were between 5-19 years; 18.5% were between 20-44 years; 16.9% were between 45-64 years of age; 38.1% were ≥ 65 years.
The percentage of tests positive for RSV continued to increase, from 6.8% in week 48 to 8.5% in week 49, primarily due to increases in detections in the Prairie Provinces. The percentage positive for rhinovirus continued to decline to 9.3%. Parainfluenza detections declined slightly (from 4.6% to 3.8%) and coronavirus detections increased slightly (from 3.4% to 4.1%). Other percentages of positive tests remained low: adenovirus 1.2%; hMPV 0.8% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (December 2 to December 8, 2012)						Cumulative (August 26, 2012 to December 8, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	6	0	6	0	0	0	76	0	70	0	6	8
AB	97	0	74	1	22	9	337	0	291	12	34	20
SK	41	0	36	1	4	2	103	0	89	1	13	8
MB	4	0	4	0	0	0	18	0	17	0	1	3
ON	289	0	212	10	67	9	701	0	532	24	145	19
QC	342	0	30	0	312	9	622	0	36	0	586	21
NB	5	0	1	2	2	0	8	0	2	3	3	0
NS	0	0	0	0	0	0	0	0	0	0	0	0
PE	1	0	1	0	0	0	4	0	4	0	0	0
NL	2	0	0	0	2	0	5	0	2	0	3	0
Canada	787	0	364	14	409	29	1874	0	1043	40	791	79

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (December 2 to December 8, 2012)					Cumulative (August 26, 2012 to December 8, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	88	2	40	46	5	238	8	139	91	12
5-19	59	0	30	29	4	197	0	138	59	13
20-44	104	1	38	65	4	308	11	176	121	12
45-64	86	1	26	59	3	273	6	152	115	19
65+	202	1	65	136	1	654	5	350	299	5
Unknown	1	0	1	0	0	5	0	4	1	0
Total	540	5	200	335	17	1675	30	959	686	61

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 71 influenza viruses [51 A(H3N2), 10 A(H1N1)pdm09 , and 10 influenza B]. The 51 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 10 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, seven were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and three were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 71

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 70 influenza viruses for resistance to oseltamivir, and 69 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 102 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	49	0	48	0	95	95 (100%)
A (H1N1)	11	0	11	0	7	7
B	10	0	10	0	NA ^*	NA ^*
TOTAL	70	0	69	0	102	102 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 49 decreased from the previous week: from 39.8 to 33.6 ILI consultations per 1,000 patient visits, which is within the expected level for this time of year (Figure 7). The highest consultation rates were observed in children <5 years of age (57.0/1,000) followed by children 5-19 years of age (53.5/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate continued to increase in week 49 to 71.8 antiviral prescriptions per 100,000 new prescriptions dispensed. The current rate of 71.8/100,000 is slightly higher than expected based on the current percentage of positive laboratory tests for influenza, and closer to the rate observed when the percentage of influenza detections was approximately 20% (data from April 2011 to present). Rates of 50-100/100,000 were observed during the peak period during the 2011-12 influenza season, when the percentage of positive influenza tests was between 18%-24%. In week 49, the highest antiviral prescription rate was among children at 122.3/100,000.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 49, 25 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: seven from AB, one from MB, six from ON, and eleven from QC. Among the 24 cases identified with influenza A, 20 were A(unsubtyped) and 4 were A(H3N2). One case was identified with influenza B. The age distribution is as follows: four under 6 months of age, nine between 6-23 months, four aged 2-4 years, six aged 5-9 years, and two aged 10-16 years. No ICU admissions or deaths were reported this week.
S
ince the start of the 2012-13 season, a total of 54 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 51 (94.4%) with influenza A [of which 12 (23.5%) were A(H3N2) and 39 (76.5%) were A(unsubtyped)], and three (5.6%) with influenza B. The distribution of cases by age group is as follows: 9 (16.7%) <6 months of age, 13 (24.1%) age 6-23 months, 14 (25.9%) age 2-4 years, 10 (18.5%) age 5-9 years, and 8 (14.8%) age 10-16 years. Five of the 54 cases (9.3%) were admitted to the ICU. No deaths have been reported to date.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 49, 112 laboratory confirmed influenza associated hospitalizations were reported [AB(12), ON(100)]. Three were influenza B, and 109 were influenza A. Of the 109 influenza A associated hospitalizations, 46% (50/109) were A(H3) and the remaining were A(unsubtyped). Almost half of the cases (49.5% 55/111) were aged 65+ and 22.5% (25/111) were aged between 45-64 years. Of the 12 cases with available data (from Alberta), none were admitted to the Intensive Care Unit (ICU). Nine deaths were reported in Ontario, all in influenza A cases: one A(unsubtyped) aged 1-4 years; one A(unsubtyped) aged 20-44 years; and 7 in persons aged ≥65 years [(3 A(H3) and 4 A(unsubtyped)].

To date this season, 224 influenza-associated hospitalizations have been reported. The majority of cases have been influenza A (97%, 217/224). Approximately half of the cases (52%, 116/223) are ≥ 65 years of age. Of the 136 influenza A hospitalizations for which subtype was available, 6.6% (9/136) were due to influenza A(H1N1)pdm09, and 88.2% (120/136) were due to A(H3). Among the 70 cases with available data, there have been 9 hospitalisations for which admission to ICU was required, four (44.4%) were persons ≥ 65 years of age. To date this season, 15 deaths have been reported: all in influenza A cases (7 A(H3); 8 A(unsubtyped)).

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #13 December 27th, 2012, 10:30 AM

Fluwatch Report: December 9 to December 15, 2012 (Week 50)

Posted 2012-12-21For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: December 9 to December 15, 2012 (Week 50) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada continued to increase in week 50; four regions reported widespread activity, and the majority of regions reported influenza circulation.
A total of 1502 laboratory detections of influenza were reported, of which 96.7% were for influenza A viruses, predominantly A(H3N2).
Thirty-one influenza outbreaks were reported: 24 in long-term-care facilities, 4 in hospitals and 3 in other facilities.
Thirty-three paediatric influenza-associated hospitalizations were reported through the IMPACT network, all but one with influenza A
Seventy-three hospitalizations with three deaths in adults ≥20 years of age were reported through Aggregate surveillance, all with influenza A.
The ILI consultation rate increased compared to the previous week and is within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 50, the majority of regions reported influenza activity with four regions [in ON] reporting widespread influenza activity, nine regions [in BC(1), AB(2), SK(1), MB(1), ON(2), QC(2)] reporting localized activity, and 23 regions reporting sporadic activity [in all provinces and territories except NL, NT and NU] (Figures 1 and 2). Thirty-one new influenza outbreaks were reported in week 50: 24 in long-term-care facilities [in BC(1), AB(3), SK(3), MB(1), ON(13), QC(2) and NS(1)], four in hospitals [in AB(1) and ON(3)], and three in other facilities [in ON] (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 50

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from 18.2% in week 49 to 24.2% in week 50 (Figure 4). Among the influenza viruses detected this week (n=1502), 96.7% were positive for influenza A viruses [of which 36.9% were A(H3), 1.2% were A(H1N1)pdm09, and 61.9% were A(unsubtyped)]; and 3.3% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 96.3% influenza A [49.5% A(H3), 1.7% A(H1N1)pdm09 and 48.8% A(unsubtyped)] and 3.7% influenza B (Table 1).
Detailed information on age and type/subtype was received for 3149 cases to date this season (Table 2). The proportions of cases by age group were as follows: 14.0% were < 5 years; 12.4% were between 5-19 years; 18.6% were between 20-44 years; 15.9% were between 45-64 years of age; 39.0% were ≥ 65 years.
The percentage of tests positive for RSV is stable at 8.7%. The percentage positive for rhinovirus continued to decline from 9.8% to 6.6%. Parainfluenza and coronavirus detections declined slightly (from 4.0% to 3.1% and from 4.2% to 3.7%, respectively). Other percentages of positive tests remained low: adenovirus 1.4%; hMPV 1.0% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (December 9 to December 15, 2012)						Cumulative (August 26, 2012 to December 15, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	19	0	19	0	0	0	112	0	106	0	6	8
AB	146	0	114	3	29	16	564	0	498	15	51	40
SK	46	0	34	2	10	0	149	0	123	3	23	8
MB	3	0	3	0	0	4	21	0	20	0	1	7
ON	465	0	281	12	172	8	1166	0	819	37	310	27
QC	762	0	81	0	681	21	1384	0	117	0	1267	42
NB	3	0	1	1	1	0	11	0	3	4	4	0
NS	1	0	0	0	1	0	1	0	0	0	1	0
PE	3	0	3	0	0	0	7	0	7	0	0	0
NL	5	0	0	0	5	0	10	0	3	0	7	0
Canada	1453	0	536	18	899	49	3425	0	1696	59	1670	132

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (December 9 to December 15, 2012)					Cumulative (August 26, 2012 to December 15, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Five provinces have reported detailed case-by-case data since the beginning of the season (BC, AB, SK,MB and ON). Delays in the reporting of data may cause data to change retrospectively.
<5	140	0	47	93	7	420	14	221	185	20
5-19	111	1	46	64	10	366	3	245	118	26
20-44	182	1	59	122	9	563	16	294	253	23
45-64	154	0	52	102	2	481	9	254	218	21
65+	464	2	131	331	17	1207	8	549	650	22
Unknown	2	0	2	0	0	10	1	8	1	0
Total	1053	4	337	712	45	3047	51	1571	1425	112

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

Since the start of the season, the National Microbiology Laboratory (NML) has antigenically characterized 125 influenza viruses [87 A(H3N2), 16 A(H1N1)pdm09 , and 22 influenza B]. The 87 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 16 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 18 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and four were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 125

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

Since the beginning of the season, NML has tested 104 influenza viruses for resistance to oseltamivir, and 101 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 132 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	73	0	70	0	122	122 (100%)
A (H1N1)	13	0	13	0	10	10
B	18	0	18	0	NA ^*	NA ^*
TOTAL	104	0	101	0	132	132 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate in week 50 increased compared to the previous week: from 30.5 to 37.9 ILI consultations per 1,000 patient visits, which is within the expected level for this time of year (Figure 7). The highest consultation rates were observed in children 5-19 years of age (80.1/1,000) followed by children <5 years of age (72.7/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate continued to increase in week 50 from 71.6 to 102.2 antiviral prescriptions per 100,000 new prescriptions dispensed. The current rate of 102.2/100,000 is in keeping with the current percentage of positive laboratory tests for influenza (24.2%).

Rates of 50-100/100,000 were observed during the peak period during the 2011-12 influenza season, when the percentage of positive influenza tests was between 18%-24% (data from April 2011 to present). In week 50, the antiviral prescription rate increased in all age categories, and was highest among children and seniors at 129.6/100,000 and 129.9/100,000, respectively.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 50, 30 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: three from BC, six from AB, two from MB, eight from ON, and eleven from QC. Among the 29 cases identified with influenza A, 24 were A(unsubtyped) and 5 were A(H3N2). One case was identified with influenza B. The age distribution is as follows: five under 6 months of age, four between 6-23 months, ten aged 2-4 years, seven aged 5-9 years, and four aged 10-16 years. Two ICU admissions were reported this week, both in children 10-16 years of age with influenza A.

Since the start of the 2012-13 season, a total of 87 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 83 (95.4%) with influenza A [of which 17 (20.5%) were A(H3N2) and 66 (79.5%) were A(unsubtyped)], and four (4.6%) with influenza B. The distribution of cases by age group is as follows: 14 (16.1%) <6 months of age, 18 (20.7%) age 6-23 months, 25 (28.7%) age 2-4 years, 18 (20.7%) age 5-9 years, and 12 (13.8%) age 10-16 years. Seven of the 87 cases (8.0%) were admitted to the ICU. No deaths have been reported to date.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System)

In week 50, 33 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: three from BC, six from AB, two from SK, two from MB, eight from ON, and twelve from QC. Among the 32 cases identified with influenza A, 27 were A(unsubtyped) and 5 were A(H3N2). One case was identified with influenza B. The age distribution is as follows: six under 6 months of age, five between 6-23 months, ten aged 2-4 years, eight aged 5-9 years, and four aged 10-16 years. Two ICU admissions were reported this week, both in children 10-16 years of age with influenza A.

Since the start of the 2012-13 season, a total of 91 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 87 (95.6%) with influenza A [of which 17 (19.5%) were A(H3N2) and 70 (80.5%) were A(unsubtyped)], and four (4.4%) with influenza B. The distribution of cases by age group is as follows: 16 (17.6%) <6 months of age, 19 (20.9%) age 6-23 months, 25 (27.5%) age 2-4 years, 19 (20.9%) age 5-9 years, and 12 (13.2%) age 10-16 years. Seven of the 91 cases (7.7%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #14 January 4th, 2013, 05:59 PM

Fluwatch Report: December 16 to December 29, 2012 (Weeks 51 & 52)

Posted 2013-01-04For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: December 16 to December 29, 2012 (Weeks 51 & 52) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Influenza activity in Canada continues to rise with increases in all indicators in weeks 51 and 52
A total of 4632 laboratory detections of influenza were reported, of which 97.7% were for influenza A viruses, predominantly A(H3N2)
127 new influenza outbreaks were reported, 87 of which were in long-term care facilities
114 new paediatric influenza-associated hospitalizations were reported through the IMPACT network, and 176 hospitalizations including 15 deaths among adults ≥20 years of age were reported through Aggregate surveillance
The ILI consultation rate increased, but remains within the expected range for this time of year.
Similar to previous years, older adults (persons aged ≥65 years) are the most affected this season; with 41.3% of laboratory detections to date, increased outbreaks in long-term care facilities, higher hospitalization rates and a high proportion of antiviral prescriptions among those ≥75 years.

Influenza Activity (geographic spread) and Outbreaks

In week 51, two regions [in ON(1) and QC(1)] reported widespread activity and 18 regions [in BC(2), AB(3), SK(2), MB(1), ON(5), QC(3), NL(1) and PE(1)] reported localized activity. In week 52, five regions [in AB(2), ON(1), QC(1) and NL(1)] reported widespread activity and 17 regions [in BC(4), AB(1), SK(1), MB(2), ON(5), QC(2), NL(1) and PE(1)] reported localized activity. In week 52, no data was reported from Yukon (Figures 1 and 2). In weeks 51 and 52, 127 new influenza outbreaks were reported: 87 in long-term-care facilities, nine in hospitals, one in a school, and 30 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 52

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests continued to increase from 24.2% in week 50 to 26.7% in week 51 and 31.1% in week 52 (Figure 4). Among the influenza viruses detected in weeks 51 and 52 (n=4632), 97.7% were positive for influenza A viruses [of which 25.7% were A(H3), 0.7% were A(H1N1)pdm09, and 73.6% were A(unsubtyped)]; and 2.3% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.1% influenza A [36.7% A(H3), 1.1% A(H1N1)pdm09 and 62.2% A(unsubtyped)] and 2.9% influenza B (Table 1).
Detailed information on age and type/subtype was received for 6888 cases to date this season (Table 2). The proportions of cases by age group were as follows: 13.6% were < 5 years; 10.1% were between 5-19 years; 16.5% were between 20-44 years; 15.8% were between 45-64 years of age; 43.9% were ≥ 65 years.
The percentage of tests positive for RSV continued to increase from 8.9% in week 50 to 9.3% in week 51 and 11.3% in week 52. The percentage of tests positive for rhinovirus declined from 7.3% in week 50 to 6.7% in week 51 and 4.8% in week 52. Parainfluenza and coronavirus detections declined slowly over the past two weeks, and were both at 2.4% in week 52. Other percentages of positive tests remained low in week 52: adenovirus 1.0%; hMPV 0.8% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (December 16 to December 29, 2012)						Cumulative (August 26, 2012 to December 29, 2012)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	113	0	77	1	35	3	225	0	183	1	41	11
AB	438	0	342	16	80	33	1006	0	866	32	108	73
SK	154	0	109	0	45	9	303	0	232	3	68	17
MB	55	0	3	0	52	6	76	0	23	0	53	13
ON	1382	0	594	12	776	30	2548	0	1436	50	1062	56
QC	2290	0	5	1	2284	23	3673	1	122	0	3550	64
NB	21	0	17	1	3	1	32	0	20	5	7	1
NS	0	0	0	0	0	0	1	0	0	0	1	0
PE	11	0	11	0	0	1	18	0	18	0	0	1
NL	61	0	6	0	55	1	71	0	16	0	55	1
Canada	4525	0	1164	31	3330	107	7953	1	2916	91	4945	237

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (December 23 to December 29, 2012)					Cumulative (August 26, 2012 to December 29, 2012)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	207	5	24	178	7	902	21	350	531	38
5-19	86	1	11	74	4	653	6	328	319	46
20-44	232	2	31	199	4	1102	23	441	638	33
45-64	234	0	22	212	5	1058	17	390	651	32
65+	880	1	83	796	9	2985	16	1003	1966	39
Unknown	2	0	0	2	0	25	2	20	3	0
Total	1641	9	171	1461	29	6725	85	2532	4108	188

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 177 influenza viruses [136 A(H3N2), 17 A(H1N1)pdm09 , and 24 influenza B]. The 136 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 17 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 20 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and four were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 177

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 128 influenza viruses for resistance to oseltamivir, and 127 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 149 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	97	0	96	0	138	138 (100%)
A (H1N1)	13	0	13	0	11	11
B	18	0	18	0	NA ^*	NA ^*
TOTAL	128	0	127	0	149	149 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 36.8 ILI consultations per 1,000 patient visits in week 50 to 32.0 in week 51. The consultation rate increased to 66.3 in week 52; however due to holiday closures only 25% of sentinel physicians reported data. This rate is within the expected level for this time of year (Figure 7). In both week 51 and 52, the highest consultation rates were observed in children <5 years of age (121.2/1,000 in week 52) followed by children 5-19 years of age (90.3/1,000 in week 52).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate continued to increase from 102.5 antiviral prescriptions per 100,000 new prescriptions dispensed in week 50 to 137.1 in week 51 and 300.8 in week 52. Rates of 50-100/100,000 were observed during the peak period during the 2011-12 influenza season, when the percentage of positive influenza tests was between 18%-24% (data from April 2011 to present). Although the current proportion of antiviral prescriptions of 300.8/100,000 is higher than the peak observed last year, it continues to follow the trend of an increasing percentage of positive laboratory tests for influenza. In week 52, the antiviral prescription rate increased in all age categories except infants, and was highest among seniors ≥75 years at 545.3/100,000.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In weeks 51 and 52, 114 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: 9 from BC, 21 from AB, 5 from SK, one from MB, 46 from ON, and 32 from QC. Among the 110 cases identified with influenza A, 91 (82.7%) were A(unsubtyped) and 19 (17.3%) were A(H3N2). Four cases were identified with influenza B. The age distribution is as follows: 19 cases (16.7%) under 6 months of age, 26 (22.8%) between 6-23 months, 33 (28.9%) aged 2-4 years, 20 (17.5%) aged 5-9 years, and 16 (14.0%) aged 10-16 years. Fourteen ICU admissions were reported during this two week period, two cases between 6-23 months, six aged 2-4 years, two aged 5-9 years, and four aged 10-16 years.

Since the start of the 2012-13 season, a total of 206 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 198 (96.1%) with influenza A [of which 36 (18.2%) were A(H3N2) and 162 (81.8%) were A(unsubtyped)], and eight (3.9%) with influenza B. The distribution of cases by age group is as follows: 36 (17.5%) <6 months of age, 44 (21.4%) age 6-23 months, 58 (28.2%) age 2-4 years, 39 (18.9%) age 5-9 years, and 29 (14.1%) age 10-16 years. Twenty-three of the 206 cases (11.2%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In weeks 51 and 52, 241 laboratory confirmed influenza associated hospitalizations were reported in five provinces (AB, MB, ON, NL, PE); the majority of which were influenza A (97% 236/241). Of the 236 influenza A associated hospitalizations, 48% (114/236) were A(H3), 1.3% (3/236) were A(H1N1pdm09) and the remaining were A(unsubtyped).Half of the cases (51% 123/241) were aged 65+ and 16.6% (40/241) were aged between 0 and 4 years. Of the 86 cases with available data, 15 (17.4%) were admitted to the Intensive Care Unit (ICU). Sixteen deaths were reported in weeks 51 and 52, all in influenza A cases: one A(unsubtyped) aged 1-4 years; 15 in persons aged ≥65 years [(4 A(H3) and 11 A(unsubtyped)].

To date this season, 565 influenza-associated hospitalizations have been reported. The majority of cases have been influenza A (552/565; 97%). Approximately half of the cases (282/565; 49.9%) are ≥ 65 years of age. Of the 297 influenza A hospitalizations for which subtype was available, 95.6% (284/297) were due to A(H3) and 4.4% (13/297) were due to influenza A(H1N1)pdm09. Among the 173 cases with available data, there have been 26 hospitalisations for which admission to ICU was required, nine (34.6%) were persons ≥ 65 years of age. To date this season, 34 deaths have been reported: all in influenza A cases (13 H3; 21 unsubtyped). Of the 34 deaths, 88.2% (30/34) were persons aged ≥ 65 years of age, 5.9% (2/34) were adults aged 20-44 years, and 5.9% (2/34) were children aged 0-4 years.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #15 January 11th, 2013, 05:03 PM

2012-2013 FluWatch report: December 30, 2012 to January 11, 2013 (Week 1)

Posted 2013-01-11For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: December 30, 2012 to January 11, 2013 (Week 1) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

Although the percentage of positive laboratory tests for influenza declined slightly in week 01, more regions across Canada reported widespread and localized influenza activity and 107 new influenza outbreaks were reported.
A total of 3864 laboratory detections of influenza were reported, of which 98.1% were for influenza A viruses, predominantly A(H3N2).
69 new paediatric influenza-associated hospitalizations were reported through the IMPACT network.
26 new adult influenza-associated hospitalizations were reported through the PCIRN-SOS network.
The ILI consultation rate decreased, but is above the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 01, 15 regions [in BC(2), AB(2), MB(1), ON(5), QC(2) and NL(3)] reported widespread activity and 20 regions [in BC(3), AB(3), SK(2), MB(3), ON(2), QC(3), NB(2), and NS(2)] reported localized activity (Figures 1 and 2). In week 01, 107 new influenza outbreaks were reported: 88 in long-term-care facilities, 5 in hospitals, one in a school, and 13 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 01

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased slightly from 34.5% in week 52 to 32.4% in week 01 (Figure 4). Among the influenza viruses detected in week 01 (n=3864), 98.1% were positive for influenza A viruses [of which 25.7% were A(H3), 1.1% were A(H1N1)pdm09, and 73.2% were A(unsubtyped)]; and 1.9% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.5% influenza A [33.2% A(H3), 1.2% A(H1N1)pdm09 and 65.6% A(unsubtyped)] and 2.5% influenza B (Table 1).
Detailed information on age and type/subtype was received for 10,867 cases to date this (Table 2). The proportions of cases by age group were as follows: 13.1% were < 5 years; 8.1% were between 5-19 years; 15.6% were between 20-44 years; 16.3% were between 45-64 years of age; 46.9% were ≥ 65 years.
The percentage of tests positive for RSV decreased slightly from 11.5% in week 52 to 10.2% in week 01. The percentage of tests positive for rhinovirus declined to 3.3% in week 01. Parainfluenza declined to 2.0% while coronavirus detections increased to 3.0% in week 01. Other percentages of positive tests remained low in week 52: adenovirus 0.6%; hMPV 0.8% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (December 30, 2012 to January 5, 2013)						Cumulative (August 26, 2012 to January 5, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	166	0	105	2	59	9	391	0	316	5	70	20
AB	262	0	172	21	69	11	1295	0	1112	65	118	85
SK	109	0	56	1	52	8	412	0	288	4	120	25
MB	48	0	19	0	29	2	124	0	42	0	82	15
ON	1286	0	579	10	697	15	3852	0	2116	60	1676	71
QC	1705	0	0	3	1702	28	6343	0	263	7	6073	100
NB	97	0	39	5	53	0	129	0	59	10	60	1
NS	12	0	0	0	12	2	13	0	0	0	13	2
PE	4	0	3	1	0	0	22	0	21	1	0	1
NL	100	0	0	0	100	0	171	0	16	0	155	1
Canada	3789	0	973	43	2773	75	12752	0	4233	152	8367	321

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (December 30, 2012 to January 5, 2013)					Cumulative (August 26, 2012 to January 5, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	239	4	28	207	17	1362	32	452	878	63
5-19	45	1	8	36	8	821	9	377	435	59
20-44	255	5	31	219	4	1656	37	618	1001	42
45-64	350	8	57	285	3	1728	35	597	1096	38
65+	1299	2	178	1119	18	5039	20	1621	3398	59
Unknown	3	0	2	1	0	48	2	44	2	0
Total	2191	20	304	1867	50	10654	135	3709	6810	261

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 193 influenza viruses [143 A(H3N2), 25 A(H1N1)pdm09 , and 25 influenza B]. The 143 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011. The 25 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 21 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and four were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 193

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 178 influenza viruses for resistance to oseltamivir, and 176 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 243 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	137	0	135	0	225	225 (100%)
A (H1N1)	18	0	18	0	18	18
B	23	0	23	0	NA ^*	NA ^*
TOTAL	178	0	176	0	243	243 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 67.1 ILI consultations per 1,000 patient visits in week 52 to 58.7 in week 01. This rate is above the expected level for this time of year, which is between 27.5 and 57.3 ILI consultations per 1,000 visits (Figure 7). In week 01, the highest consultation rates were observed in children 5-19 years of age (95.5/1,000) followed by children <5 years of age (94.1/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate continued to increase from 303.3 antiviral prescriptions per 100,000 new prescriptions dispensed in week 52 to 335.8 in week 01. Rates of 50-100/100,000 were observed during the peak period during the 2011-12 influenza season, when the percentage of positive influenza tests was between 18%-24% (data from April 2011 to present). Although the current proportion of antiviral prescriptions of 335.8/100,000 is higher than the peak observed last year, it continues to follow the trend of an increasing percentage of positive laboratory tests for influenza. In week 01, the antiviral prescription rate increased for adult and senior age groups, and decreased for infants and children. The highest rate was observed among seniors ≥65 years, at 667.3/100,000.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 01, 69 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network: 2 from BC, 9 from AB, 2 from SK, 2 from MB, 21 from ON, 31 from QC and 2 from NL.

Among the 66 cases identified with influenza A, 60 (90.9%) were A(unsubtyped), 4 (6.1%) were A(H3N2) and 2 (3.0%) were A(H1N1)pdm09. Three cases were identified with influenza B. The age distribution is as follows: 26 cases (37.7%) under 6 months of age, 12 (17.4%) between 6-23 months, 19 (27.5%) aged 2-4 years, 9 (13.0%) aged 5-9 years, and 3 (4.3%) aged 10-16 years. Four ICU admissions were reported during this week, one case between 6-23 months, two aged 2-4 years, and one aged 5-9 years.

Since the start of the 2012-13 season, a total of 342 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 330 (96.5%) with influenza A [of which 50 (15.2%) were A(H3N2), 2 (0.6%) were A(H1N1)pdm09 and 278 (84.2%) were A(unsubtyped)], and 12 (3.5%) with influenza B. The distribution of cases by age group is as follows: 77 (22.5%) <6 months of age, 69 (20.2%) age 6-23 months, 96 (28.1%) age 2-4 years, 62 (18.1%) age 5-9 years, and 38 (11.1%) age 10-16 years. Thirty-one of the 342 cases (9.1%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 01, 26 new laboratory-confirmed influenza-associated adult (16 years of age and older) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network: 1 from AB, 1 from MB, 13 from ON, 7 from QC, 2 from NB and 2 from NS. The age distribution is as follows: 19 cases (73.1%) were ≥65 years of age, 5 cases (19.2%) were aged 45-64 years, and 2 cases (7.7%) were aged 20-44 years. Among the 25 cases identified with influenza A, 4% (1/25) were A(H3N2) and 96% (24/25) were A(unsubtyped). One case was identified with influenza B. One ICU admission was reported during the current week in a case ≥65 years of age with influenza A(unsubtyped). One death was reported in a case ≥65 years of age with influenza A(unsubtyped).

From November 4, 2012 to January 5, 2013, a total of 232 influenza-associated adult hospitalizations have been reported by PCIRN-SOS network: 220 (94.8%) with influenza A [of which 29 (13.2%) were A(H3N2), 2 (0.9%) were A(H1N1)pdm09 and 189 (85.9%) were A(unsubtyped)]; 4 (1.7%) with influenza B and 8 (3.4%) were unknown.

The distribution of cases by age group is as follows: 156 cases (76%) were ≥65 years of age, 53 cases (22.8%) were aged 45-64, 20 cases (8.6%) were aged 20-44 and 3 cases (1.3%) were aged <20 years. Twelve of the 232 cases (5.2%) were admitted to the ICU. Six deaths have been reported to date, all in cases with Influenza A(unsubtyped). Five deaths were in adults ≥65 years of age, and one was in a person 20-44 years of age.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 01, 298 laboratory-confirmed influenza-associated hospitalizations were reported. Half of the cases (54% 162/298) were ≥65 years of age. Type and subtype information was available for 252 of the 298 cases. Of these 252 cases, the majority (96.4% 243/252) were influenza A and 3.6% (9/252) were influenza B. Of the 243 influenza A associated hospitalizations, 51.4% (125/243) were A(H3), 2.1% (5/243) were A(H1N1)pdm09 and the remaining were A(unsubtyped). Of the 138 cases with available data, 14.5% (20/138) were admitted to the Intensive Care Unit (ICU). Fourteen deaths were reported in week 01, all but one in persons ≥65 years of age. One death was reported in a case aged 0-4 years with influenza A. The cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 885 influenza-associated hospitalizations have been reported from all participating provinces. Half of the cases (51.3% 454/885) were ≥65 years of age, 16.9% (150/885) were adults aged 45-64 years and 15.1% (134/885) were children aged 0-4 years. Type and subtype information was available for 839 cases. Of these, 97% have been influenza A, predominately A(H3). Among the 287 cases with available data, there have been 45 hospitalisations for which admission to ICU was required, 14 (31.1%) were persons ≥65 years of age and 15 (33.3%) were in persons aged 45-64 years. To date this season, 51 deaths have been reported: 90.2% (46/51) were persons ≥65 years of age, 3.9% (2/51) were adults aged 20-44 years, and 5.9% (3/51) were children aged 0-4 years. The cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of influenza-associated hospitalizations reported by the Aggregate Surveillance System may include cases reported by the IMPACT network. Note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by SK. ICU admissions are not reported in ON.

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Pathfinder · #16 January 18th, 2013, 08:54 PM

2012-2013 FluWatch report: January 6 to January 12, 2013 (Week 2)

Posted 2013-01-18For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: January 6 to January 12, 2013 (Week 2) (PDF Version - 113 KB - 6 pages)

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Overall Influenza Summary

The percentage of positive laboratory tests for influenza declined in week 02; however, more regions across Canada reported widespread and localized influenza activity and 130 new influenza outbreaks were reported.
The ILI consultation rate increased and is well above the expected range for this time of year.
A total of 3744 laboratory detections of influenza were reported, of which 97.8% were for influenza A viruses, predominantly A(H3N2).
51 new paediatric influenza-associated hospitalizations were reported through the IMPACT network.
44 new adult influenza-associated hospitalizations were reported through the PCIRN-SOS network.

Influenza Activity (geographic spread) and Outbreaks

In week 02, 15 regions [in BC(2), AB(2), ON(5), QC(3) and NL(3)] reported widespread activity and 25 regions [in BC(2), AB(3), SK(2), MB(4), ON(2), QC(2), NB(5), NS(3), NL(1) and NU(1)] reported localized activity (Figures 1 and 2). In week 02, 130 new influenza outbreaks were reported: 98 in long-term-care facilities, 2 in hospitals, 5 in schools, and 25 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 02

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 32.5% in week 01 to 30.7% in week 02 (Figure 4).Among the influenza viruses detected in week 02 (n=3744), 97.8% were positive for influenza A viruses [of which 34.6% were A(H3), 1.9% were A(H1N1)pdm09, and 63.6% were A(unsubtyped)]; and 2.2% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.6% influenza A [34.3% A(H3), 1.4% A(H1N1)pdm09 and 64.3% A(unsubtyped)] and 2.4% influenza B (Table 1).

Detailed information on age and type/subtype was received for 13,556 cases to date this season (Table 2). The proportions of cases by age group were as follows: 12.5% were < 5 years; 7.1% were between 5-19 years; 15.1% were between 20-44 years; 16.2% were between 45-64 years of age; 49.1% were ≥ 65 years.

The percentage of tests positive for RSV was similar to week 01 (10.7%) at 10.4% in week 02. The percentage of tests positive for rhinovirus (3.9%), parainfluenza (2.3%), and coronavirus (3.6%) each increased slightly compared to the previous week. Other percentages of positive tests remained low in week 02: adenovirus 0.7%; hMPV 1.0% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (January 6 to January 12, 2013)						Cumulative (August 26, 2012 to January 12, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no test for subtyping was performed. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	217	0	146	6	65	17	608	0	519	12	77	37
AB	297	0	197	36	64	15	1628	0	1378	112	138	101
SK	121	0	78	0	43	9	533	0	366	4	163	34
MB	109	0	19	1	89	4	233	0	61	1	171	19
ON	1202	0	422	18	762	18	5053	0	2560	79	2414	89
QC	1408	0	188	7	1213	19	7780	0	451	14	7315	119
NB	212	0	212	0	0	1	341	0	271	10	60	2
NS	22	0	0	0	22	0	35	0	0	0	35	2
PE	3	0	3	0	0	0	25	0	24	1	0	1
NL	70	0	0	0	70	0	241	0	16	0	225	1
Canada	3661	0	1265	68	2328	83	16477	0	5646	233	10598	405

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (January 6 to January 12, 2013)					Cumulative (August 26, 2012 to January 12, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	172	11	35	126	5	1631	44	546	1041	68
5-19	48	1	18	29	6	892	13	410	469	66
20-44	187	10	44	133	8	1995	59	776	1160	52
45-64	249	9	48	192	7	2143	54	747	1342	51
65+	955	4	220	731	11	6584	30	2287	4267	74
Unknown	2	0	1	1	0	65	2	61	2	0
Total	1613	35	366	1212	37	13310	202	4827	8281	311

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 248 influenza viruses [172 A(H3N2), 36 A(H1N1)pdm09 , and 40 influenza B]. The 172 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 36 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 31 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 9 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 248

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 214 influenza viruses for resistance to oseltamivir, and 213 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 333 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	163	0	162	0	306	306 (100%)
A (H1N1)	25	0	25	0	27	27
B	26	0	26	0	NA ^*	NA ^*
TOTAL	214	0	213	0	333	333 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased from 58.7 ILI consultations per 1,000 patient visits in week 01 to 62.1 in week 02. This rate is well above the expected level for this time of year, which is between 24.0 and 42.5 ILI consultations per 1,000 visits (Figure 7). The increased ILI consultation rate may be due in part to ongoing influenza and RSV activity across Canada, as well as increased public attention to the early influenza season. In week 02, the highest consultation rates were observed in children <5 years of age (90.8/1,000) followed by children 5-19 years of age (78.2/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate decreased from 337.6 antiviral prescriptions per 100,000 new prescriptions dispensed in week 01 to 285.7 in week 02. In week 02, the antiviral prescription rate decreased for adult and senior age groups, and was stable for infants and children. The highest rate was observed among seniors ≥65 years, at 475.1/100,000. The current proportion of antiviral prescriptions of 285.7/100,000 is higher than the rate observed during the peak period of influenza activity last year (50-100/100,000); however, it continues to follow the trend of the percentage of positive laboratory tests for influenza.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 02, 51 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 74 in week 01. Among the 49 cases identified with influenza A, 42 (85.7%) were A(unsubtyped), 6 (12.2%) were A(H3N2) and 1 (2.0%) was A(H1N1)pdm09. Two cases were identified with influenza B. The age distribution is as follows: 10 cases (19.6%) under 6 months of age, 16 (31.4%) between 6-23 months, 16 (31.4%) aged 2-4 years, 8 (15.7%) aged 5-9 years, and 1 (2.0%) aged 10-16 years. Five ICU admissions were reported during this week, four cases between 6-23 months and one aged 2-4 years.

Since the start of the 2012-13 season, a total of 394 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 380 (96.4%) with influenza A [of which 56 (14.7%) were A(H3N2), 3 (0.8%) were A(H1N1)pdm09 and 321 (84.5%) were A(unsubtyped)], and 14 (3.6%) with influenza B. The distribution of cases by age group is as follows: 90 (22.8%) <6 months of age; 83 (21.1%) age 6-23 months; 112 (28.4%) age 2-4 years; 71 (18.0%) age 5-9 years; and 38 (9.6%) age 10-16 years. Thirty-six of the 394 cases (9.1%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 02, 44 new laboratory-confirmed influenza-associated adult (16 years of age and older) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 26 in week 01. The age distribution is as follows: 34 cases (77.3%) were ≥65 years of age, 7 cases (15.9%) were aged 45-64 years, and 3 cases (6.8%) were aged 20-44 years. Among the 42 cases identified with influenza A, one was A(H3N2), and the rest were A(unsubtyped). Two cases were identified with influenza B. One ICU admission was reported during the current week in a case of influenza A(unsubtyped) in an individual ≥65 years of age. Three deaths were reported with influenza A(unsubtyped): two individuals were ≥65 years of age, and the third was 45-64 years of age.

From November 4, 2012 to January 12, 2013, a total of 276 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 262 (94.9%) with influenza A [of which 30 (11.5%) were A(H3N2), 2 (0.8%) were A(H1N1), and 230 (87.8%) were A(unsubtyped)]; 6 (2.2%) with influenza B, and the type has not yet been reported for 8 (2.9%) cases. The distribution of cases by age group is as follows: 190 cases (68.8%) were aged ≥65 years, 60 cases (21.7%) were aged 45-64 years, 23 cases (8.3%) were aged 20-44 years, and 3 cases (1.1%) were <20 years of age. Thirteen of the 276 cases (4.7%) were admitted to the ICU. Six admissions were in adults aged ≥65 years, three were aged 45-64 years, and four were aged 20-44 years. Of the thirteen ICU admissions, eight cases (61.5%) had at least one comorbidity, one case (7.7%) had no co-morbidities, and four cases (30.8%) had no available information on comorbidities to date. Nine deaths have been reported to date, all in cases with influenza A(unsubtyped). Seven deaths were in adults aged ≥65 years, one was in a person aged 45-64 years, and one was in a person aged 20-44 years. Detailed clinical information on comorbidities is not known for these cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 02, 823 laboratory-confirmed influenza-associated hospitalizations were reported*. Ninety eight percent of cases (810/823) were influenza A [42% A(H3); 2.3% A(H1N1)pdm09; 55.7% A(unsubtyped)], and 1.6% (13/823) were influenza B. More than half of the cases (60% 497/823) were ≥65 years of age, 16.5% were adults aged 46-64 years and 13% were children aged 0-4 years. Of the 130 cases with available data, 15.4% (20/130) were admitted to the Intensive Care Unit (ICU). Fifty-one deaths were reported in week 02, the majority of which were persons ≥65 years of age (78.4%; 40/51); 10 were adults aged 45-64 yeas and one was an adult aged 20-44 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 1675 influenza-associated hospitalizations have been reported. Of these, 97.7% (1636/1675) have been influenza A [predominately A(H3) (45.7%; 748/1636)] and 2.3% have been influenza B. Half of the cases (55.7% 933/1675) were ≥65 years of age, 16.4% (275/1675) were adults aged 45-64 years and 14.4% (241/1675) were children aged 0-4 years. Among the 428 cases with available data, there have been 66 hospitalisations for which admission to ICU was required; 24 were persons ≥65 years of age, 24 were persons aged 45-64 years, 9 were adults aged 20-44 years, 1 was an individual aged 15-19 years, 3 were children aged 5-14 years and 5 were children aged 0-4 years. To date this season, 104 deaths have been reported: 86 were adults aged ≥ 65 years of age, 11 were adults aged 45-64 years; 4 were adults aged 20-44 years; and 3 were children aged 0-4 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

Pathfinder · #17 January 25th, 2013, 08:13 PM

2012-2013 FluWatch report: January 13 to January 19, 2013 (Week 3)

Posted 2013-01-25For readers interested in the PDF version, the document is available for downloading or viewing:
2012-2013 FluWatch report: January 13 to January 19, 2013 (Week 3) (PDF Version - 113 KB - 8 pages)

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Overall Influenza Summary

The percentage of positive laboratory tests for influenza declined in week 03 for the third week in a row. Influenza A(H3N2) continues to be the predominant strain in Canada.
Many regions across Canada continue to report widespread and localized influenza activity and 118 new influenza outbreaks were reported.
The ILI consultation rate decreased but continues to be above the expected range for this time of year, possibly due in part to the circulation of both influenza and RSV in many regions.
Similar to previous years, older adults (persons aged ≥65 years) are the most affected this season; with 49.4% of laboratory detections to date, 67.6% of adult hospitalizations reported through the PCIRN-SOS network, outbreaks in long-term care facilities, and a high proportion of antiviral prescriptions.

Influenza Activity (geographic spread) and Outbreaks

In week 03, 10 regions [in BC(2), AB(2), ON(1), QC(2) and NL(3)] reported widespread activity and 29 regions [in BC(2), AB(3), SK(2), MB(3), ON(6), QC(4), NB(5), NS(3), and PE(1)] reported localized activity (Figures 1 and 2). In week 03, 118 new influenza outbreaks were reported: 71 in long-term-care facilities, 6 in hospitals, 10 in schools, and 31 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 03

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=56)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Note that last year was the first year that provinces and territories were reporting on influenza outbreaks in schools (greater than 10% absenteeism on any day most likely due to ILI) which has increased considerably the total number of outbreaks reported compared to previous years.
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 30.8% in week 02 to 27.1% in week 03 (Figure 4). Among the influenza viruses detected in week 03 (n=2840), 97.9% were positive for influenza A viruses [of which 35.6% were A(H3), 3.7% were A(H1N1)pdm09, and 60.8% were A(unsubtyped)]; and 2.1% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.6% influenza A [35.6% A(H3), 1.8% A(H1N1)pdm09 and 62.6% A(unsubtyped)] and 2.4% influenza B (Table 1).
Detailed information on age and type/subtype was received for 15,833 cases to date this season (Table 2). The proportions of cases by age group were as follows: 12.6% were < 5 years; 6.9% were between 5-19 years; 14.9% were between 20-44 years; 16.1% were between 45-64 years of age; 49.4% were ≥ 65 years.
The percentage of tests positive for RSV was steady at 11.4% in week 03. The percentage of tests positive for rhinovirus (4.2%), parainfluenza (2.4%), and coronavirus (4.7%) each decreased slightly compared to the previous week. Other percentages of positive tests remained low in week 03: adenovirus 0.9%; hMPV 1.3% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (January 13 to January 19, 2013)						Cumulative (August 26, 2012 to January 19, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	255	0	149	15	91	16	805	0	684	28	93	61
AB	195	0	118	31	46	12	1823	0	1531	154	138	113
SK	73	0	33	1	39	4	606	0	399	5	202	38
MB	130	0	0	0	130	5	363	0	61	1	301	24
ON	1116	0	525	48	543	7	6200	0	3115	128	2957	97
QC	684	0	53	2	629	15	8487	0	504	16	7967	134
NB	143	0	111	5	27	0	484	0	382	15	87	2
NS	24	0	0	0	24	0	37	0	0	0	37	2
PE	12	0	0	0	12	0	37	0	24	1	12	1
NL	149	0	0	0	149	0	390	0	152	0	238	1
Canada	2781	0	989	102	1690	59	19232	0	6852	348	12032	473

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (January 13 to January 19, 2013)					Cumulative (August 26, 2012 to January 19, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	172	9	48	115	3	1921	61	645	1215	80
5-19	79	1	17	61	4	1023	15	453	555	74
20-44	203	14	78	111	8	2286	79	909	1298	71
45-64	240	11	88	141	5	2493	72	892	1529	60
65+	896	9	388	499	11	7735	40	2823	4872	90
Unknown	56	4	52	0	0	121	6	113	2	0
Total	1646	48	671	927	31	15579	273	5835	9471	375

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 285 influenza viruses [201 A(H3N2), 37 A(H1N1)pdm09 , and 47 influenza B]. The 201 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 37 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 37 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 10 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 285

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 274 influenza viruses for resistance to oseltamivir and zanamivir, respectively. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 407 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	196	0	195	0	369	369 (100%)
A (H1N1)	36	0	37	0	38	38
B	42	0	42	0	NA ^*	NA ^*
TOTAL	274	0	274	0	407	407 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 54.0 ILI consultations per 1,000 patient visits in week 02 to 43.8 in week 03. This rate is above the expected level for this time of year (between 23.5 and 36.5 ILI consultations per 1,000 visits) (Figure 7). The elevated ILI consultation rate relative to the expected range for this time of year may be due to the unusually early influenza season, as well as continued circulation of influenza and RSV across Canada. In week 03, the highest consultation rates were observed in children 5-19 years of age (60.5/1,000) followed by adults ≥65 years of age (57.9/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate increased slightly from 285.5 antiviral prescriptions per 100,000 new prescriptions dispensed in week 02 to 294.8 in week 03. In week 03, the antiviral prescription rate decreased for the adult age group, and increased for infants, children and seniors. The highest rate continued to be observed for seniors ≥65 years, at 644.8/100,000. The current proportion of antiviral prescriptions of 294.8/100,000 is higher than the rate observed during the peak period of influenza activity last year (50-100/100,000). While the percentage of positive laboratory tests for influenza has declined over recent weeks, the proportion of antiviral prescriptions continues at similar levels, possibly due to sustained influenza activity in many regions across Canada.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 03, 49 new laboratory-confirmed influenza-associated paediatric (16 years of age and under) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 61 in week 02.
Among the 47 cases identified with influenza A, 38 (80.9%) were A(unsubtyped), 5 (10.6%) were A(H3N2) and 4 (8.5%) were A(H1N1)pdm09. Two cases were identified with influenza B. The age distribution is as follows: 5 cases (10.2%) under 6 months of age, 18 (36.7%) between 6-23 months, 19 (38.8%) aged 2-4 years, 5 (10.2%) aged 5-9 years, and 2 (4.1%) aged 10-16 years. Four ICU admissions were reported during this week, two <6 months of age, one 6-23 months of age and one aged 2-4 years.

Since the start of the 2012-13 season, a total of 461 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 444 (96.3%) with influenza A [of which 61 (13.7%) were A(H3N2), 7 (1.6%) were A(H1N1)pdm09 and 376 (84.7%) were A(unsubtyped)], and 17 (3.7%) with influenza B. The distribution of cases by age group is as follows: 100 (21.7%) <6 months of age; 108 (23.4%) age 6-23 months; 135 (29.3%) age 2-4 years; 77 (16.7%) age 5-9 years; and 41 (8.9%) age 10-16 years. Forty of the 461 cases (8.7%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 03, 43 new laboratory-confirmed influenza-associated adult (16 years of age and older) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 72 in week 02. The age distribution is as follows: 25 cases (58.1%) were ≥65 years of age, 11 (25.6%) cases were aged 45-64 years, and 7 (16.3%) cases were aged 20-44 years. Among the 41 cases identified with influenza A, one was A(H3N2), and the rest were A(unsubtyped). One case was identified with influenza B, and in one case the influenza type has yet to be reported. Three ICU admissions were reported during the current week. All three had influenza A(unsubtyped), with two individuals aged ≥65 years, and the third aged 45-64 years. Three deaths were reported with influenza A(unsubtyped) in individuals ≥65 years of age.

From November 4, 2012 to January 19, 2013, a total of 539 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 504 (93.5%) with influenza A [of which 46 (9.1%) were A(H3N2), 3 (0.6%) were A(H1N1)pdm09, and 455 (90.3%) were A(unsubtyped)]; 11 (2.0%) with influenza B, and the type has not yet been reported for 24 (4.5%) cases. Among the 537 cases with available data, the distribution of cases by age group is as follows: 363 cases (67.6%) were aged ≥65 years, 119 cases (22.2%) were aged 45-64 years, 52 (9.7%) were aged 20-44 years, and 3 cases (0.6%) were <20 years of age. Thirty-two of the 539 cases (5.9%) were admitted to ICU: 19 (59.4%) were in adults aged ≥65 years, 7 (21.9%) were aged 45-64 years, and 6 (18.8%) were aged 20-44 years. Of the 32 ICU admissions, 10 cases (31.3%) had at least one co-morbidity or chronic illness, 2 (6.3%) had no co-morbidities or chronic illnesses, and 20 (62.5%) had no available information to date. A total of 25 deaths have been reported, 3 (12.0%) with influenza A(H3N2), and the remaining 22 (88.0%) with influenza A(unsubtyped). Twenty-one of the 25 deaths (84%) were in adults aged ≥65 years, three were aged 45-64 years, and one was aged 20-44 years. Three deaths occurred in individuals who had at least one co-morbidity or chronic illness. Detailed clinical information on comorbidities and chronic illnesses is not known for the remaining 22 cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

The number of laboratory confirmed influenza associated hospitalizations declined in week 03 to 583 (from 823 in week 2)*. The majority of cases were influenza A (97.8%), predominately A(H3). More than half of the cases (61.9%, 361/583) were aged 65+. Of the 96 cases with available data, 11 (11.5%) were admitted to the Intensive Care Unit (ICU). Thirty-nine deaths were reported in week 03: 30 (76.9%) were persons aged 65+; 8 (20.5%) were adults aged 45-64 yeas and one was a child aged 0-4 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 2212 influenza-associated hospitalizations have been reported. Of these, 97.8% (2164/2212) have been influenza A, predominately A(H3) [95.8% (925/966) of subtyped influenza A]; and 2.2% have been influenza B. More than half (57.6%) of the 2209 cases with available age were aged ≥65 years; 16.5% were 45-64 years; 8.4% were 20-44 years; 1.1% were 15-19 years; 3.2% were children aged 5-14 years and 13.3% were children aged 0-4 years. Among the 478 cases with available data, there have been 66 hospitalisations for which admission to ICU was required; the highest proportions were among adults ≥65 years of age (37.9%), and between 45 and 64 years of age (33.3%). To date this season, 146 deaths have been reported: 81.5% were persons aged ≥65 years of age, 13.0% were adults aged 45-64 years; 2.7% were adults aged 20-44 years and 2.7% were children aged 0-4 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #18 February 1st, 2013, 06:32 PM

FluWatch report: January 20 to January 26, 2013 (Week 4)

Posted 2013-02-01For readers interested in the PDF version, the document is available for downloading or viewing:
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Overall Influenza Summary

In week 04, several indicators of influenza activity decreased: the percentage of positive laboratory tests for influenza, the ILI consultation rate, the proportion of antiviral prescriptions, and the number of adult and paediatric influenza-associated hospitalizations reported by the PCIRN-SOS and IMPACT networks.
Many regions across Canada continue to report widespread and localized influenza activity and 104 new influenza outbreaks were reported.
The ILI consultation rate decreased but continues to be above the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 04, 7 regions [in BC(1), ON(2), QC(1) and NL(3)] reported widespread activity and 28 regions [in BC(1), AB(5), SK(1), MB(3), ON(5), QC(2), NB(6), NS(4), and PE(1)] reported localized activity (Figures 1 and 2). In week 04, 104 new influenza outbreaks were reported: 31 in long-term-care facilities, 6 in hospitals, 45 in schools, and 22 in other facilities or communities (Figure 3). The greater proportion of school outbreaks in week 04 may reflect the increasing circulation of influenza in regions where school surveillance is in place.
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 04

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Note that last year was the first year that provinces and territories were reporting on influenza outbreaks in schools (greater than 10% absenteeism on any day most likely due to ILI) which has increased considerably the total number of outbreaks reported compared to previous years.
Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 26.5% in week 03 to 22.3% in week 04 (Figure 4). Among the influenza viruses detected in week 04 (n=1919), 96.5% were positive for influenza A viruses [of which 29.9% were A(H3), 4.1% were A(H1N1)pdm09, and 66.0% were A(unsubtyped)]; and 3.5% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.5% influenza A [35.5% A(H3), 2.2% A(H1N1)pdm09 and 62.3% A(unsubtyped)] and 2.5% influenza B (Table 1).
Detailed information on age and type/subtype was received for 17,164 cases to date this season (Table 2). The proportions of cases by age group were as follows: 12.8% were < 5 years; 7.3% were between 5-19 years; 15.0% were between 20-44 years; 16.3% were between 45-64 years of age; 48.5% were ≥ 65 years.
The percentage of tests positive for RSV increased from 12.0% in week 03 to 13.7% in week 04. The percentage of tests positive for rhinovirus (4.8%) and coronavirus (5.4%) were stable compared to the previous week. Other percentages of positive tests remained low in week 04: parainfluenza 2.3%; adenovirus 0.8%; hMPV 1.4% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (January 20 to January 26, 2013)						Cumulative (August 26, 2012 to January 26, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	292	0	144	16	132	23	1005	0	820	51	134	85
AB	138	0	69	34	35	14	1976	0	1632	206	138	128
SK	56	0	39	0	17	4	662	0	438	5	219	42
MB	69	0	11	1	57	5	432	0	72	2	358	29
ON	604	0	185	24	395	15	6803	0	3332	155	3316	112
QC	360	0	23	0	337	7	8847	0	527	16	8304	141
NB	236	0	46	0	190	0	720	0	428	15	277	2
NS	32	0	24	0	8	0	69	0	24	0	45	2
PE	14	0	13	1	0	0	51	0	37	2	12	1
NL	50	0	0	0	50	0	440	0	152	0	288	1
Canada	1851	0	554	76	1221	68	21005	0	7462	452	13091	543

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (January 20 to January 26, 2013)					Cumulative (August 26, 2012 to January 26, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	108	10	24	74	5	2110	89	722	1299	94
5-19	80	3	15	62	15	1152	26	515	611	97
20-44	135	10	33	92	12	2494	117	1002	1375	86
45-64	140	15	25	100	4	2740	114	986	1640	64
65+	306	2	86	218	4	8230	47	3064	5119	97
Unknown	7	0	6	1	0	135	6	126	3	0
Total	776	40	189	547	40	16861	399	6415	10047	438

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 372 influenza viruses [269 A(H3N2), 45 A(H1N1)pdm09 , and 58 influenza B]. The 269 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 45 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 47 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 11 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 372

Note:The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 329 influenza viruses for resistance to oseltamivir, and 328 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 479 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	241	0	241	0	437	437 (100%)
A (H1N1)	40	0	39	0	42	42
B	48	0	48	0	NA ^*	NA ^*
TOTAL	329	0	328	0	479	479 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 43.8 ILI consultations per 1,000 patient visits in week 03 to 40.3 in week 04. This rate is above the expected level for this time of year (between 22.4 and 31.7 ILI consultations per 1,000 visits) (Figure 7). The elevated ILI consultation rate relative to the expected range for this time of year may be due to the unusually early influenza season, as well as continued circulation of influenza and RSV across Canada. In week 04, the highest consultation rates were observed in children 5-19 years of age (64.6/1,000) followed by children <5 years of age (58.1/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate decreased from 294.7 antiviral prescriptions per 100,000 new prescriptions dispensed in week 03 to 214.1 in week 04. In week 04, the antiviral prescription rate decreased for all age groups. The highest rate continued to be observed for seniors ≥65 years of age, at 436.7/100,000. The current proportion of antiviral prescriptions of 214.1/100,000 is higher than the rate observed during the peak period of influenza activity last year (50-100/100,000). Since week 01, the proportion of antiviral prescriptions has followed the downward trend in the percentage of positive laboratory tests for influenza.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 04, 30 new laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 52 in week 03. Among the 29 cases identified with influenza A, 26 (89.7%) were A(unsubtyped), 2 (6.9%) were A(H3N2) and 1 (3.4%) were A(H1N1)pdm09. One case was identified with influenza B. The age distribution is as follows: 4 cases (13.3%) under 6 months of age, 9 (30.0%) between 6-23 months, 5 (16.7%) 2-4 years of age, 8 (26.7%) 5-9 years of age, and 4 (13.3%) 10-16 years of age. Two ICU admissions were reported during this week, one case 6-23 months of age and one case 5-9 years of age.
Since the start of the 2012-13 season, a total of 490 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 472 (96.3%) with influenza A [of which 62 (13.1%) were A(H3N2), 8 (1.7%) were A(H1N1)pdm09 and 402 (85.2%) were A(unsubtyped)], and 18 (3.7%) with influenza B. The distribution of cases by age group is as follows: 104 (21.2%) <6 months of age; 117 (23.9%) age 6-23 months; 144 (29.4%) age 2-4 years; 83 (16.9%) age 5-9 years; and 42 (8.6%) age 10-16 years. Forty-two of the 490 cases (8.6%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associated paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)
In week 04, 44 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 57 in week 03. The age distribution is as follows: 23 cases (52.3%) were ≥65 years of age, 12 cases (27.3%) were 45-64 years of age, and 9 cases (20.5%) were 20-44 years of age. Among the 41 cases identified with influenza A, one was A(H3N2), and the rest were A(unsubtyped). Two cases were identified with influenza B, and in one case the influenza type has yet to be reported. Five ICU admissions were reported during the current week. Four had influenza A(unsubtyped), and the fifth had influenza B. Three of the ICU admissions were individuals ≥65 years of age, one was 45-64 years of age, and one was 20-44 years of age. One death was reported with influenza A(unsubtyped) in an individual ≥65 years of age.

From November 4, 2012 to January 26, 2013, a total of 685 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 647 (94.5%) with influenza A [of which 57 (8.8%) were A(H3N2), 4 (0.6%) were A(H1N1)pdm09, and 586 (90.6%) were A(unsubtyped)]; 14 (2.0%) with influenza B, and the type has not been reported for 24 (3.5%) cases. Among the 683 cases with available data, the distribution of cases by age group is as follows: 465 cases (68.1%) were aged ≥65 years, 144 cases (21.1%) were aged 45-64 years, 71 cases (10.4%) were aged 20-44 years, and 3 cases (0.4%) were <20 years of age. Fifty-nine of the 685 cases (8.6%) were admitted to the ICU. Among the 57 cases with available data: 34 (59.6%) were in adults ≥65 years of age, 16 (28.1%) were 45-64 years of age, and 7 (12.3%) were 20-44 years of age. Of the 59 ICU admissions, 15 cases (25.4%) had at least one co-morbidity, 2 (3.4%) had no co-morbidities, and 42 (71.2%) had no available information to date. A total of 34 deaths have been reported, 3 (8.8%) with influenza A(H3N2), and the remaining 31 (91.2%) with influenza A(unsubtyped). Thirty of the 34 deaths (88.2%) were in adults ≥65 years of age, three (8.8%) were 45-64 years of age, and one (2.9%) was 20-44 years of age. Nine deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on comorbidities is not known for the remaining 25 cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associated adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System)
The number of laboratory confirmed influenza associated hospitalizations declined in week 04 to 472 (from 583 in week 03)*. The majority of cases were influenza A (97.7%), predominately A(H3). More than half of the cases (62.1%, 293/472) were ≥65 years of age. Of the 104 cases with available data, 12 (11.5%) were admitted to the Intensive Care Unit (ICU). Thirty-four deaths were reported in week 04: 30 (88.2%) were persons ≥65 years of age; 2 (5.9%) were adults 45-64 years of age and 2 (5.9%) were adults 20-44 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
To date this season, 2732 influenza-associated hospitalizations have been reported. Of these, 97.7% (2671/2732) have been influenza A, predominately A(H3) [95.0% (1228/1293) of subtyped influenza A]; and 2.2% have been influenza B. More than half (58.1%) of the 2730 cases with available age were ≥65 years of age; 16.5% were 45-64 years; 8.5% were 20-44 years; 1.1% were 15-19 years; 2.9% were children aged 5-14 years and 12.9% were children 0-4 years of age. Among the 625 cases with available data, there have been 66 hospitalisations for which admission to ICU was required; the highest proportions were among adults ≥65 years of age (37.9%), and between 45 and 64 years of age (33.3%). To date this season, 182 deaths have been reported: 83.5% were persons ≥65 years of age, 11.0% were adults 45-64 years; 3.3% were adults 20-44 years and 2.2% were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

Note: * The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #19 February 8th, 2013, 05:39 PM

FluWatch report: January 27 to February 2, 2013 (Week 5)

Posted 2013-02-08For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: January 27 to February 2, 2013 (Week 5) (PDF Version - 113 KB - 8 pages)

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Overall Influenza Summary

In week 05, the percentage of laboratory detections positive for influenza was similar to the previous week; the percentage of tests positive for RSV increased sharply.
Many regions across Canada continue to report widespread and localized influenza activity and 99 new influenza outbreaks were reported.
The ILI consultation rate increased and remains above the expected range for this time of year.
The number of paediatric influenza-associated hospitalizations reported by the IMPACT network increased whereas the number of hospitalizations reported by the provinces and territories decreased.

Influenza Activity (geographic spread) and Outbreaks

In week 05, 5 regions [in BC(1), ON(1) and NL(3)] reported widespread activity and 32 regions [in BC(3), AB(5), SK(1), MB(3), ON(6), QC(4), NB(5), NS(3), NL(1) and NU(1)] reported localized activity (Figures 1 and 2). In week 05, 99 new influenza outbreaks were reported: 30 in long-term-care facilities, 3 in hospitals, 41 in schools, and 25 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 05

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests was stable at 22.4% in week 05 (Figure 4). Among the influenza viruses detected in week 05 (n=1,598), 94.6% were positive for influenza A viruses [of which 24.0% were A(H3), 5.8% were A(H1N1)pdm09, and 70.2% were A(unsubtyped)]; and 5.4% were positive for influenza B (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 97.3% influenza A [34.8% A(H3), 2.5% A(H1N1)pdm09 and 62.7% A(unsubtyped)] and 2.7% influenza B (Table 1).
Detailed information on age and type/subtype was received for 18,114 cases to date this season (Table 2). The proportions of cases by age group were as follows: 13.1% were < 5 years; 7.6% were between 5-19 years; 15.1% were between 20-44 years; 16.5% were between 45-64 years of age; 47.8% were ≥ 65 years.
The percentage of tests positive for RSV increased sharply from 14.0% in week 04 to 17.2% in week 05. The percentage of tests positive for rhinovirus increased from 5.3% in week 04 to 6.4% in week 05. The percentage of tests positive for coronavirus also increased from 5.5% in week 04 to 5.9% in week 05. Other percentages of positive tests remained low, but also increased in week 05: parainfluenza 2.6%; adenovirus 1.3%; hMPV 1.6% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (January 27 to February 2, 2013)						Cumulative (August 26, 2012 to February 2, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	255	0	135	23	97	10	1260	0	955	74	231	95
AB	99	0	44	25	30	17	2080	0	1688	249	143	146
SK	33	0	15	5	13	13	695	0	453	10	232	55
MB	67	0	3	1	63	5	499	0	75	3	421	34
ON	353	0	113	30	210	24	7155	0	3448	186	3521	136
QC	240	0	10	4	226	15	9087	0	537	20	8530	156
NB	310	0	0	0	310	1	1030	0	428	15	587	3
NS	51	0	43	0	8	0	120	0	67	0	53	2
PE	15	0	0	0	15	0	66	0	37	2	27	1
NL	88	0	0	0	88	2	527	0	152	0	375	4
Canada	1511	0	363	88	1060	87	22519	0	7840	559	14120	632

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (January 27 to February 2, 2013)					Cumulative (August 26, 2012 to February 2, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	101	5	17	79	8	2257	105	771	1381	108
5-19	59	2	4	53	11	1256	34	566	656	116
20-44	71	7	4	60	8	2633	155	1051	1427	98
45-64	96	12	13	71	7	2904	151	1040	1713	76
65+	214	3	50	161	5	8555	55	3201	5299	111
Unknown	3	1	2	0	0	148	11	135	2	0
Total	544	30	90	424	39	17753	511	6764	10478	509

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 425 influenza viruses [297 A(H3N2), 56 A(H1N1)pdm09 , and 72 influenza B]. The 297 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 56 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 58 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 14 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 425

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 397 influenza viruses for resistance to oseltamivir, and 396 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 545 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	285	0	285	0	495	495 (100%)
A (H1N1)	52	0	51	0	50	50
B	60	0	60	0	NA ^*	NA ^*
TOTAL	397	0	396	0	407	545 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased from 36.6 ILI consultations per 1,000 patient visits in week 04 to 53.7 in week 05. This rate remains above the expected level for this time of year (between 27.9 and 39.8 ILI consultations per 1,000 visits) for the sixth consecutive week (Figure 7). The elevated ILI consultation rate relative to the expected range for this time of year may be due to the continued circulation of influenza, combined with an increase in detections of RSV as well as other respiratory viruses across Canada. In week 05, the highest consultation rates were observed in children 5-19 years of age (89.6/1,000) followed by children <5 years of age (79.1/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate decreased from 213.7 antiviral prescriptions per 100,000 new prescriptions dispensed in week 04 to 186.6 in week 05; which continues to follow the downward trend in the percentage of positive laboratory tests for influenza. In week 05, the antiviral prescription rate was stable for infants, and decreased for children and adults. The highest rate continued to be observed for seniors ≥65 years of age, which increased in week 05 to 480.4/100,000. The current rate of antiviral prescriptions of 186.6/100,000 is higher than that observed during the peak period of influenza activity last year (50-100/100,000).
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.

Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 05, 46 new laboratory-confirmed, influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 34 in week 04. Among the 37 cases identified with influenza A, 33 (89.2%) were A(unsubtyped), 2 (5.4%) were A(H3N2) and 2 (5.4%) were A(H1N1)pdm09. Nine cases (19.6%) were identified with influenza B. The age distribution is as follows: 9 cases (19.6%) under 6 months of age, 7 (15.2%) between 6-23 months, 16 (34.8%) 2-4 years of age, 8 (17.4%) 5-9 years of age, and 6 (13.0%) 10-16 years of age. Two ICU admissions were reported during this week: one in a child 6-23 months of age with influenza A(unsubtyped), the other in a child 5-9 years of age with influenza B.

Since the start of the 2012-13 season, a total of 542 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 515 (95.0%) with influenza A [of which 65 (12.6%) were A(H3N2), 10 (1.9%) were A(H1N1)pdm09 and 440 (85.4%) were A(unsubtyped)], and 27 (5.0%) with influenza B. The distribution of cases by age group is as follows: 115 (21.2%) <6 months of age; 125 (23.1%) age 6-23 months; 163 (30.1%) age 2-4 years; 91 (16.8%) age 5-9 years; and 48 (8.9%) age 10-16 years. Forty-nine of the 542 cases (9.0%) were admitted to the ICU. No deaths have been reported to date.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 05, 49 new laboratory-confirmed, influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 56 in week 04. The age distribution is as follows: 32 cases (65.3%) were ≥65 years of age, 12 cases (24.5%) were 45-64 years of age, 4 cases (8.2%) were 20-44 years of age, and 1 case (2.0%) was <20 years of age. Forty-five cases identified with influenza A(unsubtyped), one case identified with influenza B, and three cases have yet to report the influenza type. Three ICU admissions were reported during the current week, all with influenza A(unsubtyped). Two of the ICU admissions were individuals ≥65 years of age, and the third was an individual 45-64 years of age. Four deaths were reported and all were identified with influenza A(unsubtyped). Three individuals were ≥65 years of age, and one was 45-64 years of age.

From November 4, 2012 to February 2, 2013, a total of 893 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 847 (94.8%) with influenza A [of which 90 (10.6%) were A(H3N2), 5 (0.6%) were A(H1N1)pdm09, and 752 (88.8%) were A(unsubtyped)]; 18 (2.0%) with influenza B, and the type has not been reported for 28 (3.1%) cases. Among 892 cases with available data, the distribution of cases by age group is as follows: 609 cases (68.3%) were aged ≥65 years, 185 cases (20.7%) were aged 45-64 years, 94 cases (10.5%) were aged 20-44 years, and 4 cases (0.4%) were <20 years of age. Seventy-eight of the 893 cases (7.1%) were admitted to the ICU.
The age distribution of the ICU cases is as follows: 47 (60.3%) were in adults ≥65 years of age, 22 (28.2%) were in adults 45-64 years of age, and 9 (11.5%) were in adults 20-44 years of age. Of the 78 ICU admissions, 21 (26.9%) had at least one co-morbidity, 2 (2.6%) had no co-morbidities, and 55 (70.5%) had no information to date. A total of 40 deaths have been reported, 3 (7.5%) with influenza A(H3N2), 36 (90.0%) with influenza A(unsubtyped), and one with influenza untyped. Thirty-four of the 40 deaths (85.0%) were in adults ≥65 years of age, five (12.5%) were adults 45-64 years of age, and one (2.5%) was 20-44 years of age. Twelve deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining 28 cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.
Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)
The number of laboratory-confirmed influenza-associated hospitalizations continued to decline in week 05 (275 compared to 472 in week 04*). The majority of cases were influenza A (96.7%), predominantly A(H3). Almost 60% of cases were ≥65 years of age (159/275). Of the 124 cases with available data, 18 (14.5%) were admitted to the ICU. Twenty-one deaths were reported in week 05: 17 were adults ≥65 years of age; three were adults 45-64 years of age and one was a child 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
To date this season, 3,010 influenza-associated hospitalizations have been reported. Of these, 97.6% have been influenza A, predominately A(H3); and 2.4% have been influenza B. Age information was available for 3,008 cases. The age distribution is as follows: 57.9% ≥65 years; 16.3% 45-64 years; 8.5% 20-44 years; 1.0% 15-19; 3.0% 5-14 years and 13.3% 0-4 years of age. Among the 755 cases with available data, there have been 109 hospitalisations for which admission to ICU was required; the highest proportions were among adults ≥65 years of age (36.7%), and between 45 and 64 years of age (34.9%). To date this season, 203 deaths have been reported: 169 were persons ≥65 years of age, 23 were adults 45-64 years; 6 were adults 20-44 years and 5 were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #20 February 15th, 2013, 04:39 PM

FluWatch report: February 3 to February 9, 2013 (Week 6)

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Overall Influenza Summary

In week 06, the percentage of laboratory detections positive for influenza continued to decrease; whereas the percentage of tests positive for RSV continued to increase.
The number of regions reporting widespread and localized influenza activity decreased, with activity primarily in central and eastern regions of Canada. Fewer new influenza/ILI outbreaks were reported compared to the past 5 weeks.
The ILI consultation rate decreased and is now within the expected range for this time of year.
Both the number of paediatric influenza-associated hospitalizations reported by the IMPACT network and the number of hospitalizations reported by the provinces and territories decreased.

Influenza Activity (geographic spread) and Outbreaks

In week 06, 5 regions [in ON(1), QC(1) and NL(3)] reported widespread activity and 29 regions [in BC(2), AB(5), SK(2), MB(1), ON(5), QC(3), NB(5), NS(5), and PE(1)] reported localized activity (Figures 1 and 2). In week 06, 72 new influenza outbreaks were reported: 35 in long-term-care facilities, 3 in hospitals, 12 in schools, and 22 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 06

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 23.3% in week 05 to 19.6% in week 06 (Figure 4). Among the influenza viruses detected in week 06 (n=1,149), 90.7% were positive for influenza A viruses [of which 32.1% were A(H3), 7.6% were A(H1N1)pdm09, and 60.3% were A(unsubtyped)]. Although influenza B remains a very small percentage of laboratory detections, the proportion has increased over the past 3 weeks from 2.1% in week 03 to 9.3% in week 06 (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 96.8% influenza A [35.5% A(H3), 2.9% A(H1N1)pdm09 and 61.6% A(unsubtyped)] and 3.2% influenza B (Table 1).

Detailed information on age and type/subtype was received for 18,920 cases to date this season (Table 2). The proportion of cases by age group were as follows: 13.1% were < 5 years; 7.8% were between 5-19 years; 15.2% were between 20-44 years; 16.6% were between 45-64 years of age; 47.3% were ≥ 65 years.

The percentage of tests positive for RSV continued to increase from 17.6% in week 05 to 19.9% in week 06. The percentage of tests positive for rhinovirus decreased from 6.5% in week 05 to 5.3% in week 06. The percentage of tests positive for coronavirus also decreased from 5.3% in week 05 to 4.8% in week 06. Other percentages of positive tests remained low in week 06: parainfluenza increased to 2.7%; hMPV increased to 2.4%; adenovirus decreased to 0.8% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (February 3 to February 9, 2013)						Cumulative (August 26, 2012 to February 9, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	250	0	142	24	84	30	1886	0	1419	148	319	161
AB	83	0	38	24	21	14	2174	0	1741	286	147	164
SK	32	0	7	7	18	19	727	0	460	17	250	74
MB	38	0	3	1	34	1	537	0	78	4	455	35
ON	184	0	83	19	82	13	7396	0	3533	205	3658	151
QC	167	0	4	3	160	30	9254	0	541	23	8690	186
NB	144	0	0	0	144	0	1174	0	428	15	731	3
NS	66	0	57	1	8	0	186	0	124	1	61	2
PE	12	0	1	0	11	0	78	0	47	3	28	1
NL	66	0	0	0	66	0	593	0	152	0	441	4
Canada	1042	0	335	79	628	107	24005	0	8523	702	14780	781

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (February 3 to February 9, 2013)					Cumulative (August 26, 2012 to February 9, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	63	10	7	46	19	2354	121	796	1437	133
5-19	27	1	3	23	24	1321	44	597	680	152
20-44	70	4	6	60	13	2760	180	1099	1481	121
45-64	75	13	11	51	11	3046	178	1101	1767	91
65+	188	2	34	152	7	8822	60	3328	5434	120
Unknown	5	4	1	0	0	156	15	139	2	0
Total	428	34	62	332	74	18459	598	7060	10801	617

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 513 influenza viruses. The 374 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 60 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 64 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 15 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 513

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 447 influenza viruses for resistance to oseltamivir, and 444 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 562 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	319	0	318	0	511	511 (100%)
A (H1N1)	57	0	55	0	51	51
B	71	0	71	0	NA ^*	NA ^*
TOTAL	447	0	444	0	562	562 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 52.8 ILI consultations per 1,000 patient visits in week 05 to 34.9 in week 06. After 6 weeks with ILI rates above the expected level for this time of year, the rate in week 06 is within the expected range (Figure 7). In week 06, the highest consultation rate was observed in children 5-19 years of age (62.8/1,000) followed by nearly identical rates for children <5 years of age (30.9/1,000) and adults 20-64 years of age (30.0/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)

Pharmacy Surveillance

The Canadian antiviral prescription rate decreased from 186.3 antiviral prescriptions per 100,000 new prescriptions dispensed in week 05 to 151.7 in week 06; which continues to follow the downward trend in the percentage of positive laboratory tests for influenza. In week 06, the antiviral prescription rate increased for infants, and decreased for other age-groups. The highest rate continued to be observed for seniors ≥65 years of age, which decreased in week 06 to 453.8/100,000.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 06, 38 new laboratory-confirmed, influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 48 in week 05. Among the 30 cases identified with influenza A, 24 (80.0%) were A(unsubtyped), 2 (6.7%) were A(H3N2) and 4 (13.3%) were A(H1N1)pdm09. Eight cases (21.1%) were identified with influenza B. The age distribution is as follows: 7 cases (18.4%) under 6 months of age, 6 (15.8%) between 6-23 months, 15 (39.5%) 2-4 years of age, 8 (21.1%) 5-9 years of age, and 2 (5.3%) 10-16 years of age. Three ICU admissions were reported during this week.

Since the start of the 2012-13 season, a total of 576 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 540 (93.8%) with influenza A [of which 66 (12.2%) were A(H3N2), 14 (2.6%) were A(H1N1)pdm09 and 460 (85.2%) were A(unsubtyped)], and 36 (6.3%) with influenza B. The distribution of cases by age group is as follows: 120 (20.8%) <6 months of age; 132 (22.9%) age 6-23 months; 175 (30.4%) age 2-4 years; 98 (17.0%) age 5-9 years; and 51 (8.9%) age 10-16 years. Fifty of the 576 cases (8.7%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)
In week 06, 40 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 67 in week 05. Of the 39 cases with age information, the distribution is as follows: 24 cases (61.5%) were ≥65 years of age, 10 cases (25.6%) were 45-64 years of age, and 5 cases (12.8%) were 20-44 years of age. Thirty-six cases were identified with influenza A(unsubtyped), two cases with influenza B, and two cases have yet to report the influenza type. Three ICU admissions were reported during the current week, two with influenza A(unsubtyped) and one with influenza B. Of the ICU admissions, one individual was ≥65 years of age, one 45-64 years of age, and one 20-44 years of age. Two deaths were reported, both were ≥65 years of age with influenza A(unsubtyped).

From November 4, 2012 to February 9, 2013, a total of 1,057 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,001 (94.7%) with influenza A [of which 121 (12.1%) were A(H3N2), 5 (0.5%) were A(H1N1)pdm09, and 875 (87.4%) were A(unsubtyped)]; 23 (2.2%) with influenza B, and the type has not been reported for 33 (3.1%) cases. Among 1,056 with available data, the distribution of cases by age group is as follows: 721 cases (68.3%) were aged ≥65 years, 218 cases (20.6%) were aged 45-64 years, 113 cases (10.7%) were aged 20-44 years, and 4 cases (0.4%) were <20 years of age. Ninety-one of the 1,057 (8.6%) were admitted to the ICU; the majority of which were persons ≥65 years of age (58.2%). Of the 91 ICU admissions, 27 (29.7%) had at least one co-morbidity, 2 (2.2%) had no co-morbidities, and 62 (68.1%) had no information to date. A total of 45 deaths have been reported, 4 (8.9%) with influenza A(H3N2), 39 (86.7%) with influenza A(unsubtyped), one with influenza B (2.2%), and one (2.2%) with influenza untyped. Thirty-nine of the 45 deaths (86.7%) were in adults ≥65 years of age, five (11.1%) were adults 45-64 years of age, and one (2.2%) was 20-44 years of age. Eighteen deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining 27 cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

The number of laboratory confirmed influenza associated hospitalizations continued to decline in week 06 (251 compared to 275 in week 05*). The majority of cases were influenza A (94.4%), predominately A(H3). Over half of cases were ≥65 years of age (131/251, 52.9%). Of the 82 cases with available data, 17 (20.7%) were admitted to the Intensive Care Unit (ICU). Twelve deaths were reported: 10 were adults ≥65 years of age; one 45-64 years of age and one 20-44 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 3262 influenza-associated hospitalizations have been reported. Of these, 97.2% have been influenza A, predominately A(H3); and 2.8% have been influenza B. Age information was available for 3260 cases, and the age distribution is as follows: 57.4% ≥65 years; 16.4% 45-64 years; 8.5% 20-44 years; 1.0% 15-19; 3.3% 5-14 years and 13.3% 0-4 years of age. Among the 836 cases with available data, there have been 127 (15.2%) hospitalisations for which admission to ICU was required; the highest proportions were among adults aged 45-64 years of age (37.0%), and ≥65 years of age (34.6%). To date this season, 217 deaths have been reported: 180 (83.0%) were persons ≥65 years of age, 25 (11.5%) were adults 45-64 years; 7 (3.2%) were adults 20-44 years and 5 (2.3%) were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #21 February 22nd, 2013, 05:48 PM

FluWatch report: February 10 to February 16, 2013 (Week 7)

Posted 2013-02-22For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 10 to February 16, 2013 (Week 7) (PDF Version - 113 KB - 8 pages)

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Overall Influenza Summary

In week 07, several indicators of influenza circulation continued to decrease, including: the percentage of laboratory detections positive for influenza, the number of regions reporting widespread and localized activity, the number of new influenza/ILI outbreaks, and influenza-associated hospitalizations reported by the IMPACT network and by participating provinces and territories.
The percentage of tests positive for RSV was stable at 19.6% and the percentage of tests positive for rhinovirus increased slightly.
The ILI consultation rate increased slightly but is within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 07, 4 regions [in ON(1), QC(1) and NL(2)] reported widespread activity and 19 regions [in BC(1), SK(1), ON(5), QC(2), NB(5), NS(1), PE(1), NL(2) and NU(1)] reported localized activity (Figures 1 and 2). In week 07, 45 new influenza outbreaks were reported: 23 in long-term-care facilities, 3 in hospitals, 5 in schools, and 14 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 07

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 17.0% in week 06 to 15.2% in week 07 (Figure 4). Among the influenza viruses detected in week 07 (n=926), 86.8% were positive for influenza A viruses [of which 28.6% were A(H3), 8.0% were A(H1N1)pdm09, and 63.4% were A(unsubtyped)] (Table 1). The proportion of influenza B detections has increased over the past 4 weeks from 2.1% in week 03 to 13.2% in week 07(Figure 4). Cumulative influenza virus detections by type/subtype to date are as follows: 96.4% influenza A [35.2% A(H3), 3.1% A(H1N1)pdm09 and 61.7% A(unsubtyped)] and 3.6% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 19,508 cases to date this (Table 2). The proportion of cases by age group is as follows: 13.2% < 5 years; 7.9% between 5-19 years; 15.3% between 20-44 years; 16.7% between 45-64 years of age; 46.9% ≥ 65 years.
The percentage of tests positive for RSV in week 07 (19.6%) was similar to week 06. The percentage of tests positive for rhinovirus increased from 5.7% in week 06 to 7.6% in week 07. The percentages of tests positive for coronavirus and parainfluenza were similar to the previous week at 4.8% and 2.3%, respectively. Other percentages of positive tests increased slightly in week 07: hMPV at 2.9%; adenovirus at 1.5% (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
Reporting provinces	Weekly (February 10 to February 16, 2013)						Cumulative (August 26, 2012 to February 16, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	150	0	90	14	46	21	1899	0	1462	150	287	181
AB	49	0	21	21	7	32	2227	0	1770	317	140	197
SK	20	0	6	9	5	7	747	0	466	26	255	81
MB	25	0	0	2	23	4	562	0	78	6	478	39
ON	199	0	65	14	120	30	7647	0	3599	219	3829	190
QC	135	0	4	1	130	27	9389	0	545	24	8820	214
NB	134	0	0	0	134	1	1308	0	428	15	865	4
NS	46	0	38	3	5	0	232	0	162	4	66	2
PE	6	0	6	0	0	0	84	0	53	3	28	1
NL	40	0	0	0	40	0	633	0	152	0	481	4
Canada	804	0	230	64	510	122	24728	0	8715	764	15249	913

Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
Age groups	Weekly (February 10 to February 16, 2013)					Cumulative (August 26, 2012 to February 16, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	54	10	8	36	12	2425	141	818	1466	152
5-19	23	2	7	14	25	1356	47	611	698	189
20-44	48	9	6	33	14	2837	200	1132	1505	142
45-64	63	6	7	50	9	3149	195	1133	1821	105
65+	128	3	24	101	10	9016	65	3419	5532	137
Unknown	0	0	0	0	0	159	16	141	2	0
Total	316	30	52	234	70	18942	664	7254	11024	725

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 569 influenza viruses. The 405 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 76 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 73 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 15 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 569

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 517 influenza viruses for resistance to oseltamivir, and 514 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 651 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	382	0	381	0	589	589 (100%)
A (H1N1)	58	0	56	0	62	62
B	77	0	77	0	NA ^*	NA ^*
TOTAL	517	0	514	0	651	651 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased slightly from 34.2 ILI consultations per 1,000 patient visits in week 06 to 38.0 in week 07, likely due in part to the circulation of other respiratory viruses such as RSV. After 6 weeks with ILI rates above the expected level for this time of year from weeks 52 to 05, the rate has been within the expected range for weeks 06 and 07 (Figure 7). In week 07, the highest consultation rate was observed in children 5-19 years of age (73.9/1,000) followed by children <5 years of age (54.0/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate decreased from 151.0 antiviral prescriptions per 100,000 new prescriptions dispensed in week 06 to 123.3 in week 07; which continues to follow the downward trend in the percentage of positive laboratory tests for influenza. In week 07, the antiviral prescription rate decreased for all age-groups. The highest rate continued to be observed for seniors ≥65 years of age, at 379.9/100,000.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 07, 22 new laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 40 in week 06. Among the 15 cases identified with influenza A, 13 (86.7%) were A(unsubtyped), 1 (6.7%) was A(H3N2) and 1 (6.7%) was A(H1N1)pdm09. Seven cases (31.8%) were identified with influenza B. The age distribution is as follows: 4 cases (18.2%) under 6 months of age, 5 (22.7%) between 6-23 months, 6 (27.3%) 2-4 years of age, 5 (22.7%) 5-9 years of age, and 2 (9.1%) 10-16 years of age. No ICU admissions were reported during week 07.

Since the start of the 2012-13 season, a total of 597 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 554 (92.8%) with influenza A [of which 67 (12.1%) were A(H3N2), 16 (2.9%) were A(H1N1)pdm09 and 471 (85.0 %) were A(unsubtyped)], and 43 (7.2%) with influenza B. The distribution of cases by age group is as follows: 122 (20.4%) <6 months of age; 137 (22.9%) age 6-23 months; 182 (30.5%) age 2-4 years; 104 (17.4%) age 5-9 years; and 52 (8.7%) age 10-16 years. Fifty-one of the 576 cases (8.5%) were admitted to the ICU. No deaths have been reported to date.
Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 07, 39 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 49 in week 06. The majority of hospitalizations continue to be adults aged ≥65 years25 cases (64.1%). Thirty-eight cases identified with influenza A: 37 with influenza A(unsubtyped), and one with influenza A(H3N2). The influenza type has not been reported for one case. Nine ICU admissions were reported during the current week, all with influenza A(unsubtyped). Six of the nine adults admitted to the ICU were ≥65 years of age, two were 45-64 years of age, and one was 20-44 years of age. Three deaths were reported and all identified with influenza A(unsubtyped):two individuals were ≥65 years of age, and the third was 45-64 years of age.

From November 4, 2012 to February 16, 2013, a total of 1,195 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,130 (94.6%) with influenza A [of which 143 (12.7%) were A(H3N2), 6 (0.5%) were A(H1N1)pdm09, 981 (86.8%) were A(unsubtyped).]; and 24 (2.0%) with influenza B, and the influenza type has not been reported for 41 (3.4%) cases. Among 1,194 cases with available data, the age distribution is as follows: 816 cases (68.3%) were aged ≥65 years, 246 cases (20.6%) were aged 45-64 years, 128 cases (10.7%) were aged 20-44 years, and 4 cases (0.3%) were <20 years of age. Of the 1,195 cases, 111 (9.3%) were admitted to the ICU. The age distribution of those admitted to the ICU is as follows: 65 (58.6%) were in adults ≥65 years of age, 32 (28.8%) were in adults 45-64 years of age, and 14 (12.6%) were in adults 20-44 years of age. Of the adults admitted to the ICU, 33 (29.7%) had at least one co-morbidity, two (1.8%) had no co-morbidities, and 76 (68.5%) had no information to date. A total of 53 deaths have been reported, 7 (13.2%) with influenza A(H3N2), 44 (83.0%) with influenza A(unsubtyped), and 1 (1.9%) with influenza B, and one (1.9%) for which the influenza type has not been reported. Forty-six of the 53 deaths (86.8%) were in adults ≥65 years of age, 6 (11.3%) were adults 45-64 years of age, and 1 (1.9%) was 20-44 years of age. Twenty-three deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining 30 cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

The number of laboratory-confirmed influenza-associated hospitalizations continued to decline in week 07 (126 compared to 251 in week 06*). The majority of cases were influenza A (95.2%), predominately A(H3). Over half of cases were ≥65 years of age (67/126, 53.2%). Of the 49 cases with available data, 10 (20.4%) were admitted to the Intensive Care Unit (ICU). Twelve deaths were reported: 11 were adults ≥65 years of age, and one 20-44 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 3316 influenza-associated hospitalizations have been reported. Of these, 97.2% have been influenza A, predominately A(H3); and 2.8% have been influenza B. Age information was available for 3260 cases, and the age distribution is as follows: 57.2% ≥65 years; 16.5% 45-64 years; 8.5% 20-44 years; 1.0% 15-19; 3.4% 5-14 years and 13.4% 0-4 years of age. Among the 890 cases with available data, there have been 140 (15.7%) hospitalisations for which admission to ICU was required; the highest proportions were among adults aged 45-64 years of age (37.1%), and ≥65 years of age (35.0%). To date this season, 217 deaths have been reported: 180 (83.0%) were adults ≥65 years of age, 25 (11.5%) were adults 45-64 years; 7 (3.2%) were adults 20-44 years and 5 (2.3%) were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

Pathfinder · #22 March 1st, 2013, 04:09 PM

FluWatch report: February 17 to February 23, 2013 (Week 8)

Posted 2013-03-01For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 17 to February 23, 2013 (Week 8) (PDF Version - 113 KB - 8 pages)

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Overall Summary

In week 08, specific indicators of influenza activity continued to decrease, while indicators of the circulation of respiratory viruses such as the ILI consultation rate were similar to recent weeks.
The percentage of laboratory detections positive for influenza continues to decrease, while the proportion of positive tests for influenza B has increased in recent weeks. The percentage of laboratory detections positive for RSV and rhinovirus were similar to recent weeks.
The number of regions reporting widespread or localized activity was similar in weeks 07 and 08; however, there is an overall decline in influenza/ILI activity from the peak in early January.

Influenza Activity (geographic spread) and Outbreaks

In week 08, 2 regions [in ON(1) and NL(1)] reported widespread activity and 22 regions [in BC(2), AB(1), MB(1), ON(5), QC(3), NB(2), NS(5), NL(2) and NU(1)] reported localized activity. The number of regions reporting widespread or localized activity was similar in weeks 07 and 08; however, there is an overall decline in influenza/ILI activity from the peak in early January (Figures 1 and 2). In week 08, 34 new influenza outbreaks were reported: 18 in long-term-care facilities, 3 in hospitals, 2 in schools, and 11 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 08

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests continued to decline, from 14.1% in week 07 to 12.7% in week 08 (Figure 4). Among the influenza viruses detected in week 08 (n=671), 71.5% were positive for influenza A viruses [of which 29.8% were A(H3), 11.7% were A(H1N1)pdm09, and 58.5% were A(unsubtyped)] (Table 1). The proportion of A(H1N1)pdm09 among positive influenza A detections has increased from 1.0% in week 52 to 11.7% in week 08. The proportion of influenza B detections has increased over the past 5 weeks from 2.1% in week 03 to 28.5% in week 08 (Figure 4). Cumulative influenza virus detections by type/subtype to date are as follows: 95.8% influenza A [35.1% A(H3), 3.3% A(H1N1)pdm09 and 61.6% A(unsubtyped)] and 4.2% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 20,023 cases to date this season (Table 2). The proportion of cases by age group is as follows: 13.3% < 5 years; 8.2% between 5-19 years; 15.3% between 20-44 years; 16.7% between 45-64 years of age; 46.6% ≥ 65 years.
The percentage of tests positive for RSV in week 08 (20.5%) was similar to weeks 06 and 07. The percentage of tests positive for rhinovirus in week 08 (8.5%) was similar to week 07. In week 08, the percentages of tests positive for coronavirus and parainfluenza both decreased slightly at 3.8% and 2.1%, respectively. The percentage of tests positive increased slightly for hMPV (3.2%) and was stable for adenovirus (1.3%) (Figure 5). For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (February 17 to February 23, 2013)						Cumulative (August 26, 2012 to February 23, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	94	0	65	17	12	29	1908	0	1494	170	244	208
AB	40	0	17	16	7	50	2267	0	1787	338	142	247
SK	11	0	1	2	8	12	758	0	467	28	263	93
MB	17	0	0	0	17	0	579	0	78	6	495	39
ON	129	0	48	18	63	43	7776	0	3651	237	3888	233
QC	102	0	1	2	99	57	9491	0	546	26	8919	271
NB	15	0	0	0	15	0	1323	0	428	15	880	4
NS	28	0	3	1	24	0	260	0	165	5	90	2
PE	8	0	8	0	0	0	92	0	61	3	28	1
NL	36	0	0	0	36	0	669	0	152	0	517	4
Canada	480	0	143	56	281	191	25123	0	8829	828	15466	1102

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (February 17 to February 23, 2013)					Cumulative (August 26, 2012 to February 23, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	35	3	5	27	23	2479	149	832	1498	181
5-19	16	2	5	9	59	1376	51	623	702	264
20-44	40	11	7	22	14	2899	220	1152	1527	162
45-64	48	10	5	33	16	3215	214	1156	1845	126
65+	105	4	25	76	17	9159	73	3478	5608	162
Unknown	5	2	3	0	0	164	18	144	2	0
Total	249	32	50	167	129	19292	725	7385	11182	895

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 624 influenza viruses. The 425 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 86 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 94 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 19 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 624

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 583 influenza viruses for resistance to oseltamivir, and 581 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 695 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	412	0	412	0	630	630 (100%)
A (H1N1)	77	0	76	0	65	65
B	94	0	93	0	NA ^*	NA ^*
TOTAL	583	0	581	0	695	695 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased slightly from 37.0 ILI consultations per 1,000 patient visits in week 07 to 33.2 in week 08. After 6 weeks with ILI rates above the expected level for this time of year (from weeks 52 to 05), the rate has been within the expected range since week 06 (Figure 7). In week 08, the highest consultation rate was observed in children <5 years of age (64.3/1,000), followed by children 5-19 years of age (62.6/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate was stable at 123.1 antiviral prescriptions per 100,000 new prescriptions dispensed in week 08, which continues to follow the downward trend in the percentage of positive laboratory tests for influenza. In week 08, the antiviral prescription rate decreased for all age-groups except seniors. The highest rate continued to be observed for seniors ≥65 years of age, at 460.4/100,000.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 08, 18 new laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 27 in week 07. Among the cases reported in week 08, 11 (61.1%) were identified with influenza A and 7 (38.9%) with influenza B. The age distribution is as follows: 2 cases (11.1%) under 6 months of age, 7 (38.9%) between 6-23 months, 6 (33.3%) 2-4 years of age, 2 (11.1%) 5-9 years of age, and one (5.6%) 10-16 years of age. One ICU admission was reported during week 08 in a child between 6-23 months of age with influenza A.

Since the start of the 2012-13 season, a total of 620 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 571 (92.1%) with influenza A [of which 67 (11.7%) were A(H3N2), 15 (2.6%) were A(H1N1)pdm09 and the remaining 489 were A(unsubtyped)], and 49 (7.9%) with influenza B. The distribution of cases by age group is as follows: 125 (20.2%) <6 months of age; 142 (22.9%) age 6-23 months; 191 (30.8%) age 2-4 years; 110 (17.7%) age 5-9 years; and 52 (8.4%) age 10-16 years. Fifty-four of the 620 cases (8.7%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 08, 20 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 51 in week 07. The majority of hospitalizations (16) were cases with influenza A: one influenza A(H3N2) and the rest A(unsubtyped). Four cases were reported with influenza B. The age distribution is as follows: 12 cases were ≥65 years of age, 7 cases were 45-64 years of age, and one case was 20-44 years of age. Four ICU admissions were reported during the current week, three with influenza A(unsubtyped) and one with influenza B. Two individuals admitted to the ICU were ≥65 years of age and two were 45-64 years of age. No deaths were reported this week.

From November 4, 2012 to February 23, 2013, a total of 1,300 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,226 (94.3%) cases with influenza A [of which 162 (13.2%) were A(H3N2), 8 (0.7%) were A(H1N1)pdm09, and 1,056 (86.1%) were A(unsubtyped)]; 33 (2.5%) cases with influenza B; and 41 (3.2%) cases for which the influenza type has not yet been reported. The age distribution of hospitalizations is as follows: 895 cases (68.8%) were aged ≥65 years, 265 cases (20.4%) were aged 45-64 years, 135 cases (10.4%) were aged 20-44 years, and 5 cases (0.4%) were <20 years of age. There have been 121 hospitalizations for which admission to the ICU was required; the majority of which were adults ≥65 years of age (58.7%). Of the 121 ICU admissions, 37 (30.6%) had at least one co-morbidity, two (1.7%) had no co-morbidities, and 82 had no information to date. A total of 53 deaths have been reported, 8 (15.1%) with influenza A(H3N2), 43 (81.1%) with influenza A(unsubtyped), one (1.9%) with influenza B, and one (1.9%) with influenza untyped. Forty-six of the 53 deaths (86.8%) were in adults ≥65 years of age, 6 (11.3%) were adults 45-64 years of age, and one (1.9%) was 20-44 years of age. Twenty-four deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 08, 231 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories*. The majority of cases were influenza A (88.3%), predominantly A(H3). The proportion of cases of influenza B among hospitalizations has been increasing in recent weeks. The highest proportion of hospitalisations were adults ≥65 years (42.9%), followed by adults aged 46-64 (20.3%) and children aged 0-4 years (18.2%). Of the 61 cases with available data, 10 (16.4%) were admitted to the Intensive Care Unit (ICU). Fourteen deaths were reported: 12 were adults ≥65 years of age, one adult aged 45-64 years and one adult 20-44 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

To date this season, 3,625 influenza-associated hospitalizations have been reported. Of these, 96.6% have been influenza A, predominately A(H3); and 3.4% have been influenza B. Age information was available for 3,622 cases, and the age distribution is as follows: 56.4% ≥65 years; 16.8% 45-64 years; 8.7% 20-44 years; 0.9% 15-19; 3.6% 5-14 years and 13.6% 0-4 years of age. Among the 952 cases with available data, there have been 148 (15.5%) hospitalisations for which admission to ICU was required; the highest proportions were among adults aged 45-64 years of age (37.8%), and ≥65 years of age (33.8%). To date this season, 243 deaths have been reported: 203 were adults ≥65 years of age, 26 were adults 45-64 years; 9 were adults 20-44 years and 5 were children 0-4 years of age. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #23 March 8th, 2013, 04:20 PM

FluWatch report: February 24 to March 2, 2013 (Week 9)

Posted 2013-03-09For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: February 24 to March 2, 2013 (Week 9) (PDF Version - 113 KB - 8 pages)

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Overall Summary

Detections of influenza A and B increased slightly, primarily in Eastern Canada. The proportion of positive tests for influenza B has increased in recent weeks.
The number of paediatric hospitalizations was similar to the previous 2 weeks. In week 09, 50% of cases were associated with influenza B.
Nationally, the number of regions reporting widespread or localized activity, as well as the ILI consultation rate continued to decline.
The percentage of laboratory detections positive for RSV and rhinovirus both decreased.

Influenza Activity (geographic spread) and Outbreaks

In week 09, 2 regions [in ON(1) and NL(1)] reported widespread activity and 18 regions [in BC(1), AB(1), SK(1), MB(1), ON(5), QC(5), NB(1), NS(2), and NL(1)] reported localized activity. The number of regions reporting widespread or localized activity decreased compared to the previous week and continued to follow the overall decline in influenza/ILI activity from the peak in early January (Figures 1 and 2). Thirty-one new influenza outbreaks were reported: 21 in long-term-care facilities, 3 in hospitals, and 7 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 09

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests increased from 12.1% in week 08 to 14.9% in week 09 (Figure 4). Among the influenza viruses detected in week 09 (n=793), 64.1% were positive for influenza A viruses [of which 20.5% were A(H3), 17.3% were A(H1N1)pdm09, and 62.2% were A(unsubtyped)] (Table 1). The proportion of influenza B detections has increased over the past 6 weeks from 2.1% in week 03 to 35.9% in week 09 (Figure 4). The increase in influenza B detections in week 09 was driven primarily by data from Quebec, where 64.6% of influenza detections were influenza B. The proportion of influenza B was also high in Alberta (52.2%) and Saskatchewan (45.8%) compared to other provinces ^*. Cumulative influenza virus detections by type/subtype to date are as follows: 94.8% influenza A [35.1% A(H3), 3.6% A(H1N1)pdm09 and 61.3% A(unsubtyped)] and 5.2% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 20,521 cases to date this season (Table 2). The proportion of cases by age group is as follows: 13.3% < 5 years; 8.4% between 5-19 years; 15.3% between 20-44 years; 16.8% between 45-64 years of age; 46.1% ≥ 65 years.
The percentage of tests positive for RSV decreased slightly from 21.3% in week 08 to 17.7% in week 09. The percentage of tests positive for rhinovirus also decreased from 8.7% in week 08 to 6.2% in week 09. The percentage of tests positive decreased slightly for both coronavirus (2.7%) and hMPV (2.6%). The percentage of tests positive increased slightly for both parainfluenza virus (2.1%) and adenovirus (1.5%) (Figure 5)^*.
* For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (February 24 to March 2, 2013)						Cumulative (August 26, 2012 to March 2, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	53	0	28	19	6	26	1836	0	1412	186	238	249
AB	33	0	6	21	6	36	2228	0	1722	361	145	281
SK	13	0	0	6	7	11	771	0	467	34	270	104
MB	12	0	0	0	12	5	591	0	78	6	507	44
ON	128	0	32	15	81	56	7904	0	3685	255	3964	289
QC	81	0	0	0	81	148	9572	0	546	26	9000	419
NB	136	0	33	27	76	1	1721	0	723	42	956	5
NS	28	0	0	0	28	1	288	0	165	5	118	3
PE	5	0	5	0	0	0	97	0	66	3	28	1
NL	19	0	0	0	19	1	688	0	152	0	536	5
Canada	508	0	104	88	316	285	25696	0	9016	918	15762	1400

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (February 24 to March 2, 2013)					Cumulative (August 26, 2012 to March 2, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	28	6	2	20	29	2519	159	836	1524	219
5-19	14	1	0	13	60	1398	57	625	716	331
20-44	25	6	3	16	26	2948	245	1165	1538	197
45-64	24	4	7	13	43	3265	230	1172	1863	175
65+	68	4	14	50	32	9267	79	3511	5677	202
Unknown	0	0	0	0	0	164	18	144	2	0
Total	159	21	26	112	190	19561	788	7453	11320	1124

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 703 influenza viruses. The 463 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 93 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 115 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 32 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 703

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 633 influenza viruses for resistance to oseltamivir, and 632 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 819 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	430	0	430	0	724	724 (100%)
A (H1N1)	85	0	84	0	95	95
B	118	0	118	0	NA ^*	NA ^*
TOTAL	633	0	632	0	819	819 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 31.8 ILI consultations per 1,000 patient visits in week 08 to 20.5 in week 09 and is below the expected range for week 09 (Figure 7). In week 09, the highest consultation rate was observed in children <5 years of age (28.2/1,000), followed by children 5-19 years of age (25.3/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate increased slightly from 85.7 antiviral prescriptions per 100,000 new prescriptions dispensed in week 08 to 102.5/100,000 in week 09. The antiviral prescription rate decreased for children and adults, and increased slightly among infants, but this rate was the lowest of all age-groups at 32.5/100,000. The highest rate continued to be observed for seniors ≥65 years of age, which increased in week 09 to 350.8/100,000.
Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 09, 26 new laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 23 in week 08. Among the cases reported in week 09, 50.0% (13) were identified with influenza B and 50.0% with influenza A [12 A(unsubtyped) and one A(H1N1)pdm09]. More hospitalizations were reported in older age groups compared to the previous week. The age distribution is as follows: 3 cases (11.5%) under 6 months of age, 6 (23.1%) between 6-23 months, 4 (15.4%) 2-4 years of age, 9 (34.6%) 5-9 years of age, and 4 (15.4%) 10-16 years of age. Two ICU admissions were reported during week 09, both with influenza B.

Since the start of the 2012-13 season, a total of 654 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 589 (90.1%) with influenza A [of which 66 (11.2%) were A(H3N2), 16 (2.7%) were A(H1N1)pdm09 and the remaining 507 were A(unsubtyped)], and 65 (9.9%) with influenza B. The distribution of cases by age group is as follows: 131 (20.0%) <6 months of age; 150 (22.9%) age 6-23 months; 196 (30.0%) age 2-4 years; 120 (18.3%) age 5-9 years; and 57 (8.7%) age 10-16 years. Fifty-six of the 654 cases (8.6%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 09, 15 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network, compared to 31 in week 08. The majority of hospitalizations (12) were cases with influenza A(unsubtyped), and three cases were reported with influenza B. The age distribution is as follows: 11 cases were ≥65 years of age, 3 cases were 45-64 years of age, and one case was 20-44 years of age. One ICU admission was reported during the current week, an adult ≥65 years of age with influenza A(unsubtyped). No deaths were reported this week.

From November 4, 2012 to March 2, 2013, 1,385 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,309 (94.5%) cases with influenza A [of which 187 were A(H3N2), 9 were A(H1N1)pdm09, and 1,113 were A(unsubtyped)]. Thirty-seven (2.7%) hospitalizations were cases with influenza B; and the type has not been reported for 39 (2.8%) cases. The age distribution of hospitalizations is as follows: 952 (68.7%) were aged ≥65 years, 280 (20.2%) were aged 45-64 years, 147 (10.6%) were aged 20-44 years, and 6 (0.4%) were <20 years of age. There have been 133 hospitalizations for which admission to the ICU was required; the majority (58.6%) of which were adults ≥65 years of age. Of the 133 ICU admissions, 44 (33.1%) had at least one co-morbidity, two (1.5%) had no co-morbidities, and 87 had no information to date. A total of 65 deaths have been reported, 11 (16.9%) with influenza A(H3N2), 52 (80.0%) with influenza A(unsubtyped), one (1.5%) with influenza B, and one (1.5%) with influenza untyped. Fifty-four of the 65 deaths (83.1%) were in adults ≥65 years of age, 9 (13.8%) were adults 45-64 years of age, and two (3.1%) were 20-44 years of age. Twenty-eight deaths occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.
Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)
In week 09, 112 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*. The majority of cases were influenza A (83.0%), predominantly A(H3). The highest proportion of hospitalisations continued to be adults ≥65 years of age (45.5%). Of the 34 cases with available data, 5 were admitted to the Intensive Care Unit (ICU). Eleven deaths were reported: eight were adults ≥65 years of age, two adults aged 45-64 years and one child aged 5-14 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
To date this season 3,739 influenza-associated hospitalizations have been reported. Of these, 96.2% have been influenza A and 3.8% have been influenza B. Age information was available for 3,736 cases; and the age distribution is as follows: 2,093 (56.0%) ≥65 years; 629 (16.8%) 45-64 years; 328 (8.8%) 20-44 years; 34 (0.9%) 15-19; 140 (3.7%) 5-14 years and 512 (13.7%) 0-4 years of age. Among the 988 cases with available data, there have been 153 (15.5%) hospitalisations for which admission to ICU was required; the highest proportions being adults aged 45-64 years of age and ≥65 years of age (37.2% and 34.6% respectively). To date this season, 254 deaths have been reported: 211 (83.1%) were adults ≥65 years of age, 28 (11.0%) were adults 45-64 years; 9 were adults 20-44 years, one child aged 5-14 years and 5 aged 0-4 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.
* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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Pathfinder · #24 March 15th, 2013, 07:00 PM

FluWatch report: March 3 to March 9, 2013 (Week 10)

Posted 2013-03-15For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 3 to March 9, 2013 (Week 10) (PDF Version - 113 KB - 8 pages)

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Overall Summary

Overall detections of influenza continued to decline, however the proportion of influenza B detections increased.
In week 10, 75% of paediatric hospitalizations were associated with influenza B.
Nationally, the number of regions reporting widespread or localized activity decreased.
The ILI consultation rate increased but was within the expected range for this time of year.

Influenza Activity (geographic spread) and Outbreaks

In week 10, one region [in ON] reported widespread activity and 14 regions [in AB(1), ON(4), QC(3), NB(2), NS(2), PE(1) and NL(1)] reported localized activity. The number of regions reporting widespread or localized activity decreased compared to the previous week and continued to follow the overall decline in influenza/ILI activity from the peak in early January (Figures 1 and 2). Twenty-three new influenza outbreaks were reported: 19 in long-term-care facilities, 1 in a hospital, and 3 in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 10

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 14.6% in week 09 to 13.5% in week 10 (Figure 4). Among the influenza viruses detected in week 10 (n=616), 55.7% were positive for influenza A viruses [of which 26.5% were A(H3), 20.4% were A(H1N1)pdm09, and 53.1% were A(unsubtyped)] (Table 1). The proportion of influenza B detections has increased over the past 7 weeks from 2.1% in week 03 to 44.3% in week 10 (Figure 4). The proportion of A(H1N1)pdm09 among positive influenza A detections has increased from 1.0% in week 52 to 20.4% in week 10. Cumulative influenza virus detections by type/subtype to date are as follows: 94.0% influenza A [35.0% A(H3), 3.8% A(H1N1)pdm09 and 61.2% A(unsubtyped)] and 6.0% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 21,007 cases to date this season (Table 2). The proportion of cases by age group is as follows: 13.5% < 5 years; 8.6% between 5-19 years; 15.4% between 20-44 years; 16.8% between 45-64 years of age; 45.7% ≥ 65 years.
The percentage of tests positive decreased slightly for RSV, from 18.1% in week 09 to 17.3% in week 10; and increased for both parainfluenza (3.4%) and hMPV (4.8%). The percentage of tests positive for rhinovirus (8.7%), coronavirus (3.6%) and adenovirus (1.5%) were similar to previous weeks (Figure 5)^*.
* For more details, see the weekly Respiratory Virus Detections in Canada Report.

**Table 1: Weekly & Cumulative numbers of positive influenza specimens**
**by Provincial Laboratories, Canada, 2012-2013**
Reporting provinces	Weekly (March 3 to March 9, 2013)						Cumulative (August 26, 2012 to March 9, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	30	0	13	8	9	23	1846	0	1420	185	241	272
AB	24	0	8	13	3	40	2254	0	1733	377	144	322
SK	22	0	1	17	4	9	793	0	468	51	274	113
MB	13	0	0	2	11	3	604	0	78	8	518	47
ON	87	0	30	19	38	35	7990	0	3720	276	3994	324
QC	57	0	1	3	53	157	9629	0	547	29	9053	576
NB	74	0	34	8	32	4	1795	0	757	50	988	9
NS	24	0	0	0	24	0	312	0	165	5	142	3
PE	4	0	4	0	0	0	101	0	70	3	28	1
NL	8	0	0	0	8	2	696	0	152	0	544	7
Canada	343	0	91	70	182	273	26020	0	9110	984	15926	1674

**Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups**
**reported through case-based laboratory reporting, Canada, 2012-2013** Table 2 note*
Age groups	Weekly (March 3 to March 9, 2013)					Cumulative (August 26, 2012 to March 9, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	17	3	1	13	43	2556	168	841	1547	274
5-19	6	0	1	5	59	1411	59	627	725	399
20-44	36	10	6	20	32	3007	267	1176	1564	236
45-64	22	10	1	11	31	3310	250	1180	1880	214
65+	54	6	14	34	39	9347	91	3542	5714	253
Unknown	0	0	0	0	0	164	18	144	2	0
Total	135	29	23	83	204	19795	853	7510	11432	1376

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Figure 4. Influenza tests reported and percentage of tests positive, Canada,
by report week, 2012-2013

Text equivalent for figure 4Influenza tests reported and percentage of tests positive, Canada, by report week, 2011-2012
Figure 5. Percent positive influenza tests, compared to other respiratory viruses,
Canada, by reporting week, 2012-2013

Text equivalent for figure 5Percent positive influenza tests, compared to other respiratory viruses, Canada, by reporting week, 2011-2012

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Influenza strain characterizations

During the 2012-13 season, the National Microbiology Laboratory (NML) has antigenically characterized 730 influenza viruses. The 464 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 103 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 127 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 36 were similar to B/Brisbane/60/2008 (Victoria lineage; component of the 2011-2012 seasonal influenza vaccine) (Figure 6).
Figure 6. Influenza strain characterizations, Canada, 2012-2013, N = 730

Note: The recommended components for the 2012-2013 Northern Hemisphere influenza vaccine include: an A/Victoria/361/2011 (H3N2)-like virus; an A/California/7/2009 (H1N1)pdm09-like virus; and a B/Wisconsin/1/2010-like virus.
Text equivalent for figure 6Influenza strain characterizations, Canada, 2011-2012

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Antiviral resistance

During the 2012-13 season, NML has tested 699 influenza viruses for resistance to oseltamivir, and 696 influenza viruses for resistance to zanamivir. All viruses tested were sensitive to oseltamivir and zanamivir. A total of 859 influenza A viruses were tested for amantadine resistance and all were resistant (Table 3).

**Table 3. Antiviral resistance by influenza virus type and subtype, Canada, 2012-2013**
Virus type and subtype	Oseltamivir		Zanamivir		Amantadine
Virus type and subtype	# tested	# resistant (%)	# tested	# resistant (%)	# tested	# resistant (%)
^* NA - not applicable
A (H3N2)	460	0	459	0	756	756(100%)
A (H1N1)	94	0	92	0	103	103
B	145	0	145	0	NA ^*	NA ^*
TOTAL	699	0	696	0	859	859 (100%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased from 20.9 ILI consultations per 1,000 patient visits in week 09 to 30.7 in week 10 and is within the expected range for week 10 (Figure 7). In week 10, the highest consultation rate was observed in children 5-19 years of age (70.1/1,000).
Figure 7. Influenza-like illness (ILI) consultation rates, Canada, by report week, 2012-2013 compared to 1996/97 through to 2011/12 seasons (with pandemic data suppressed)

Note: No data available for mean rate in previous years for weeks 19 to 39 (1996-1997 through 2002-2003 seasons). Delays in the reporting of data may cause data to change retrospectively.
Text equivalent for figure 7Influenza-like illness (ILI) consultation rates, Canada, by report week, 2011-2012 compared to 1996/97 through to 2010/11 seasons (with pandemic data suppressed)
Pharmacy Surveillance

The Canadian antiviral prescription rate decreased slightly from 111.1 antiviral prescriptions per 100,000 new prescriptions dispensed in week 09 to 85.7/100,000 in week 10. The antiviral prescription rate was stable for children and decreased among all other age-groups. The highest rate continued to be observed for seniors ≥65 years of age, which decreased in week 10 to 289.0/100,000.

Note: Pharmacy sales data are provided to the Public Health Agency of Canada by Rx Canada Inc. and sourced from major retail drug chains representing over 3,000 stores nationwide (excluding Nunavut) in 85% of Health Regions. Data provided include the number of new antiviral prescriptions (for Tamiflu and Relenza) and the total number of new prescriptions dispensed by Province/Territory and age group.
Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)
In week 10, 20 new laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 43 in week 09. Among the cases reported in week 10, 75% (15) were identified with influenza B and 25% (5) with influenza A(unsubtyped). For the second week in a row, the number of influenza B cases exceeded the number of influenza A cases, a reversal of the pattern seen earlier in the season. The age distribution is as follows: 4 cases (20.0%) under 6 months of age, 3 (15.0%) between 6-23 months, 6 (30.0%) 2-4 years of age, 5 (25.0%) 5-9 years of age, and 2 (10.0%) 10-16 years of age. Two ICU admissions were reported during week 10, one 6-23 months of age, one between 2-4 years of age, both with influenza B.

Since the start of the 2012-13 season, a total of 694 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 601 (86.6%) with influenza A [of which 67 (11.1%) were A(H3N2), 16 (2.7%) were A(H1N1)pdm09 and the remaining 518 were A(unsubtyped)], and 93 (13.4%) with influenza B. The distribution of cases by age group is as follows: 139 (20.0%) <6 months of age; 160 (23.1%) age 6-23 months; 206 (29.7%) age 2-4 years; 130 (18.7%) age 5-9 years; and 59 (8.5%) age 10-16 years. Sixty of the 694 cases (8.6%) were admitted to the ICU. No deaths have been reported to date.

Note: The number of hospitalizations reported through IMPACT represents a subset of all influenza-associate paediatric hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.

Adult Influenza Hospitalizations and Deaths (PCIRN)

In week 10, 21 new laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations were reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network. Seventy-six percent of the hospitalizations were among cases identified with influenza A(unsubtyped) and the rest were with influenza B. Ten cases were ≥65 years of age, seven were 45-64 years of age, and four were 20-44 years of age. Three ICU admissions were reported during the current week all with influenza A(unsubtyped): one case was 20-44 years of age and the two others ≥65 years of age. Two deaths were reported, both were ≥65 years of age, one with influenza A(H3N2) and influenza A(unsubtyped).

From week 45 to week 10, 1,474 influenza-associated adult hospitalizations have been reported by the PCIRN-SOS network: 1,382 (93.8%) with influenza A [of which 198 were A(H3N2), 11 were A(H1N1)pdm09, and 1173 were A(unsubtyped). Forty-six hospitalizations were among cases with influenza B, and the type has not been reported for 46 cases. The age distribution of hospitalizations is as follows: 1014 cases (68.9%) were aged ≥65 years, 293 cases (19.9%) were aged 45-64 years, 157 cases (10.7%) were aged 20-44 years, and 8 cases (0.5%) were <20 years of age. There have been 146 (9.9%) hospitalizations for which admission to the ICU was required: the majority (61.0%) were adults ≥65 years of age. Of the ICU admissions, 51 (34.9%) had at least one co-morbidity, two (1.4%) had no co-morbidities, and 93 had no information to date. A total of 77 deaths have been reported: 74 (96.0%) with influenza A [13 (17.6%) with influenza A(H3N2), one (1.4%) with influenza A(H1N1)pdm09 and 60 (81.1%) with influenza A(unsubtyped)], and 2 (2.6%) with influenza B, and one with influenza for which the type has not been reported. Sixty-four of the 77 deaths (83.1%) were in adults ≥65 years of age, 9 (14.3%) were adults 45-64 years of age, and 2 (2.6%) was 20-44 years of age. Thirty-three deaths (42.9%) occurred in individuals who had at least one co-morbidity. Detailed clinical information on co-morbidities is not known for the remaining cases.

Note: The number of hospitalizations reported through PCIRN represents a subset of all influenza-associate adult hospitalizations in Canada. Delays in the reporting of data may cause data to change retrospectively.

Provincial/Territorial Influenza Hospitalizations and Deaths (Aggregate Surveillance System^*)

In week 10, 108 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*. The majority of cases were influenza A (88; 81.5%), predominantly A(H3). The highest proportion of hospitalisations continued to be adults ≥65 years of age (54.6%). Of the 25 cases with available data, 7 were admitted to the ICU - all adults ≥ 20 years and older. Fifteen deaths were reported: 12 were adults ≥65 years of age, 1 aged 45-64 years and 2 aged 20-44 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases. Data was not received for the Northwest Territories in week 10.

To date this season 3,849 influenza-associated hospitalizations have been reported; compared to 281 hospitalizations reported for the same time period during the 2011-2012 influenza season. Of the hospitalizations to date, 95.7% have been influenza A. The cumulative proportion of hospitalizations in cases with influenza B has increased from 1.6% in week 01, to 4.2% in week 10; which follows the trend of influenza B detections in Canada this season.

Age information was available for 3,846 cases, and the age distribution is as follows: 2,152 (56.0%) were ≥65 years; 645 (16.8%) 45-64 years; 342 (8.9%) 20-44 years; 37 (1.0%) 15-19; 145 (3.8%) 5-14 years and 525 (13.7%) 0-4 years of age. Among the 1,015 cases with available data, there have been 160 (15.8%) hospitalisations for which admission to ICU was required; the highest proportions being adults aged 45-64 years of age and ≥65 years of age (36.9% and 35.6% respectively). To date, 269 deaths have been reported: 223 (82.9%) were adults ≥65 years of age, 29 (10.8%) were adults 45-64 years; 11 (4.1%) were adults 20-44 years, one child aged 5-14 years and 5 (1.9%) aged 0-4 years. It is important to note that the cause of death does not have to be attributable to influenza, a positive laboratory test is sufficient for reporting. Detailed clinical information (e.g. underlying medical conditions) is not known for these cases.

* Note: The number of new influenza-associated hospitalizations and deaths reported by the Aggregate Surveillance System each week may be overestimated, as it may include retrospective updates to data from Ontario for previous weeks. These data may also include cases reported by the IMPACT and PCIRN networks. Influenza-associated hospitalizations are not reported to PHAC by the following Provinces and Territory: BC, NU, QC, NS, and NB. Only hospitalizations that require intensive medical care are reported by Saskatchewan. ICU admissions are not reported in Ontario.

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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

Pathfinder · #25 March 22nd, 2013, 04:41 PM

FluWatch report: March 10 to March 16, 2013 (Week 11)

Posted 2013-03-22For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: March 10 to March 16, 2013 (Week 11) (PDF Version - 113 KB - 8 pages)

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Overall Summary

Overall detections of influenza continued to decline, however the proportion of influenza B detections increased.
The proportions of tests positive for other respiratory viruses increased.
In week 11, 62% of paediatric hospitalizations were associated with influenza B.
Several indicators, including the number of regions reporting widespread or localized activity, the ILI consultation rate, and the proportion of prescriptions for antivirals decreased in week 11.
Similar to previous years, older adults (persons aged ≥65 years) are the most affected this season; with 45.0% of laboratory detections to date, 69.2% of adult hospitalizations reported through the PCIRN-SOS network, outbreaks in long-term care facilities, and the highest proportion of antiviral prescriptions.

Influenza Activity (geographic spread) and Outbreaks

In week 11, one region [in ON] reported widespread activity and 12 regions [in BC(1), AB(1), ON(6), QC(1), NS(2) and NL(1)] reported localized activity. The number of regions reporting widespread or localized activity decreased compared to the previous week and continued to follow the overall decline in influenza/ILI activity from the peak in early January (Figures 1 and 2). Twenty-four new influenza outbreaks were reported: 17 in long-term-care facilities, one in a hospital, one in a school, and five in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 11

Note: Influenza activity levels, as represented on this map, are assigned and reported by Provincial and Territorial Ministries of Health, based on laboratory confirmations, sentinel ILI rates (see graphs and tables) and reported outbreaks. Please refer to detailed definitions on the last page. For areas where no data is reported, late reports from these provinces and territories will appear on the FluWatch website.
Text equivalent for figure 1Map of overall Influenza activity level by province and territory, Canada
Figure 2. Number of influenza surveillance regions^† reporting widespread or localized influenza activity, Canada, by report week, 2012-2013 (N^*=58)

†sub-regions within the province or territory as defined by the provincial/territorial epidemiologist. Graph may change as late returns come in.
* Total number of influenza surveillance regions in Canada
Text equivalent for figure 2Number of influenza surveillance regions reporting widespread or localized influenza activity, Canada, by report week, 2011-2012 (N=56)
Figure 3. Overall Number of Influenza Outbreaks, Canada, by Report Week, 2012-2013

Text equivalent for figure 3Overall Number of Influenza Outbreaks, Canada, by Report Week, 2011-2012

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Influenza and Other Respiratory Virus Detections

The percentage of positive influenza tests decreased from 13.1% in week 10 to 12.2% in week 11 (Figure 4). Among the influenza viruses detected in week 10 (n=507), 55.4% were positive for influenza A viruses [of which 22.6% were A(H3), 20.8% were A(H1N1)pdm09, and 56.6% were A(unsubtyped)] (Table 1). The proportion of influenza B detections has increased over the past 8 weeks from 2.1% in week 03 to 55.4% in week 11 (Figure 4). Cumulative influenza virus detections by type/subtype to date are as follows: 93.0% influenza A [34.9% A(H3), 4.0% A(H1N1)pdm09 and 61.1% A(unsubtyped)] and 7.0% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 22,036 cases to date this season (Table 2). ). The proportion of cases by age group is as follows: 13.7% < 5 years; 8.9% between 5-19 years; 15.6% between 20-44 years; 16.8% between 45-64 years of age; 45.0% ≥ 65 years.
The percentage of tests positive decreased for RSV, from 17.6% in week 10 to 15.4% in week 11. The percentage of positive tests increased for all other viruses: rhinovirus (9.4%), hMPV (5.2%), coronavirus (4.2%), parainfluenza (4.1%) and adenovirus (1.9%) (Figure 5)^*.
* For more details, see the weekly Respiratory Virus Detections in Canada Report.

Table 1: Weekly & Cumulative numbers of positive influenza specimens
by Provincial Laboratories, Canada, 2012-2013
Reporting provinces	Weekly (March 10 to March 16, 2013)						Cumulative (August 26, 2012 to March 16, 2013)
	Influenza A					Influenza B	Influenza A					Influenza B
	A Total	A(H1)	A(H3)	Pand H1N1	A ( Un S)Table 1 note*	Total	A Total	A(H1)	A(H3)	Pand H1N1	A (Un S) Table 1 note*	Total
* Unsubtyped: The specimen was typed as influenza A, but no result for subtyping was available. Specimens from NT, YT, and NU are sent to reference laboratories in other provinces. Note: Weekly data is based on week of positive lab detection. Cumulative data includes updates to previous weeks; due to reporting delays, the sum of weekly report totals do not add up to cumulative totals.
BC	32	0	15	12	5	27	1872	0	1435	200	237	299
AB	21	0	8	10	3	47	2276	0	1741	391	144	370
SK	16	0	6	8	2	15	809	0	474	59	276	128
MB	7	0	0	0	7	3	611	0	78	8	525	50
ON	68	0	20	16	32	50	8070	0	3743	294	4033	391
QC	43	0	0	1	42	136	9671	0	546	30	9095	712
NB	9	0	0	0	9	1	1804	0	757	50	997	10
NS	23	0	0	0	23	0	335	0	165	5	165	3
PE	2	0	2	0	0	0	104	0	73	3	28	1
NL	5	0	0	0	5	2	701	0	152	0	549	9
Canada	226	0	51	47	128	281	26253	0	9164	1040	16049	1973

Table 2. Weekly & Cumulative numbers of positive influenza specimens by age groups
reported through case-based laboratory reporting, Canada, 2012-2013 Table 2 note*
Age groups	Weekly (March 10 to March 16, 2013)					Cumulative (August 26, 2012 to March 16, 2013)
	Influenza A				B	Influenza A				B
	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total	A Total	Pandemic H1N1	A/H3N2	A unsubtyped	Total
* Please note that this table reflects the number of specimens for which demographic information was reported. These represent a subset of all positive influenza cases reported. Delays in the reporting of data may cause data to change retrospectively.
<5	10