Canada FluWatch Weekly Reports 2012-2013 Season Week 19 - Page 2

Pathfinder · #31 May 17th, 2013, 05:03 PM

FluWatch report: April 28 to May 4, 2013 (Week 18)

Posted 2013-05-10For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: April 28 to May 4, 2013 (Week 18) (PDF Version - 113 KB - 8 pages)

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Overall Summary

Influenza activity in Canada continued its slow decline in week 18, with the percentage of laboratory tests positive for influenza at 10%. Influenza B was the predominant strain, but detections continued to decrease.
Detections of rhinovirus continued to increase, while detections of other respiratory viruses were stable or decreasing in week 18.
The ILI consultation rate increased slightly and was above the expected range. However, fewer regions reported localized activity compared to the previous week.

Influenza Activity (geographic spread) and Outbreaks

In week 18, seven regions [AB(1), ON(4), QC(1) and NB(1)] reported localized activity and 25 regions reported sporadic activity. The number of regions reporting widespread or localized activity decreased compared to the previous week (Figures 1 and 2). Six new influenza outbreaks were reported: five in long-term-care facilities and one in a school (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 18

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 overall percentage of positive influenza tests decreased slightly compared to recent weeks, from 11.2 in week 17 to 10.0% in week 18. Detections of influenza B decreased for the second consecutive week, and represented 86.4% of total positive influenza detections in week 18 (Figure 4). Among the influenza viruses detected in week 18 (n=301), 13.6% were positive for influenza A viruses [of which 48.8% were A(H1N1)pdm09, 9.8% were A(H3), and 41.5% were A(unsubtyped)] (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 86.5% influenza A [34.5% A(H3), 4.6% A(H1N1)pdm09 and 61.0% A(unsubtyped)] and 13.5% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 23,888 cases to date this season (Table 2). The proportion of cases by age group is as follows: 14.1% <5 years; 9.9% between 5-19 years; 15.7% between 20-44 years; 17.0% between 45-64 years of age; 43.2% ≥65 years.
The percentage of positive tests for rhinovirus increased from 12.5% in week 17 to 14.1% in week 18, and has been slowly increasing since week 01. The percentage of positive tests for parainfluenza (5.4%) was stable since week 16, but has been increasing gradually over the past 10 weeks. The percentage of tests positive for respiratory syncytial virus (RSV) (4.5%) continued its decline from a peak in week 08. The percentage of positive tests for human metapneumovirus (hMPV) (5.0%) has been stable since week 16, and the percentage of positive tests for coronavirus (0.8%) has been decreasing slowly since week 04 (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 (April 28 to May 4, 2013)						Cumulative (August 26, 2012 to May 4, 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	3	0	1	2	0	11	1907	0	1450	218	239	397
AB	7	0	2	4	1	40	2347	0	1766	437	144	748
SK	2	0	0	0	2	27	836	0	476	73	287	285
MB	0	0	0	0	0	2	657	0	78	10	569	84
ON	7	0	1	4	2	57	8248	0	3778	369	4101	843
QC	12	0	0	2	10	109	9797	0	546	35	9216	1768
NB	6	0	0	6	0	13	1859	0	771	71	1017	60
NS	0	0	0	0	0	1	388	0	165	8	215	7
PE	2	0	0	2	0	0	116	0	76	9	31	1
NL	2	0	0	0	2	0	717	0	152	0	565	16
Canada	41	0	4	20	17	260	26872	0	9258	1230	16384	4209

**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 (April 28 to May 4, 2013)					Cumulative (August 26, 2012 to May 4, 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	5	2	0	3	32	2674	214	861	1599	706
5-19	0	0	0	0	34	1455	66	639	750	908
20-44	4	1	0	3	23	3170	339	1217	1614	586
45-64	4	2	0	2	27	3463	312	1233	1918	597
65+	2	0	0	2	45	9611	132	3713	5766	718
Unknown	0	0	0	0	0	166	20	144	2	1
Total	15	5	0	10	161	20539	1083	7807	11649	3516

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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 1221 influenza viruses. The 600 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 193 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 338 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 90 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 =1221

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 1149 influenza viruses for resistance to oseltamivir, and 1145 influenza viruses for resistance to zanamivir. Among these, one A(H3N2) virus was resistant to oseltamivir and zanamivir. A total of 1180 influenza A viruses were tested for amantadine resistance and all but one 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)	572	1 (0.2%)	573	1 (0.2%)	955	954 (99.9%)
A (H1N1)	194	0	190	0	225	225 (100%)
B	383	0	382	0	NA ^*	NA ^*
TOTAL	1149	1 (0.1%)	1145	1 (0.1%)	1180	1179 (99.9%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate increased from 14.5 ILI consultations per 1,000 patient visits in week 17 to 17.6 / 1,000 in week 18, and is above the expected range (Figure 7). In week 18, the highest consultation rate was observed in children under 5 years of age (63.2/1,000).
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)

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Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 18, 16 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 15 in week 17. All of the cases reported in week 18 were identified with influenza B. The age distribution is as follows: 3 (18.8%) between 0-5 months, 2 (12.5%) between 6-23 months, 4 (25.0%) 2-4 years of age, and 7 (43.8%) 5-9 years of age. Two cases were admitted to an intensive care unit (ICU) during week 18, one child 2-4 years of age and one 5-9 years of age; both with influenza B. No deaths were reported in week 18.
Since the start of the 2012-13 season, a total of 855 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 621 (72.6%) with influenza A [of which 120 (19.3%) were A(H3N2), 25 (4.0%) were A(H1N1)pdm09 and the remaining 476 were A(unsubtyped); and 234 (27.4%) with influenza B. The distribution of cases by age group is as follows: 157 (18.4%) <6 months of age; 199 (23.3%) age 6-23 months; 244 (28.5%) age 2-4 years; 183 (21.4%) age 5-9 years; and 72 (8.4%) age 10-16 years. Ninety-two (10.8%) of the 855 cases were admitted to the ICU. Of the 70 ICU admissions with available data, 60 (85.7%) cases had at least one co-morbidity. One death has been reported to date this season in a child 6-23 months of age with an underlying condition, with influenza B.

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)

PCIRN-SOS surveillance has concluded for the 2012-13 influenza season. In week 18, eight 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. All eight hospitalizations were cases of influenza B; three cases were ≥65 years of age, two were 45-64 years, two were 20-44 years and one was <20 years of age. Two ICU admissions were reported, both cases with influenza B; one ≥65 years of age and one 45-64 years of age. No deaths were reported in week 18. Only nine of the 17 PCIRN centres reported data in week 18. A summary of final data will be included in the 2012-13 FluWatch annual report.

From November 4, 2012 to May 4, 2013, 1,779 influenza-associated adult hospitalizations were reported by the PCIRN-SOS network: 1,620 (91.1%) with influenza A [of which 310 were A(H3N2), 19 were A(H1N1)pdm09, and 1,291 were A(unsubtyped)]; 113 (6.4%) with influenza B, and the type has not been reported for 46 cases. The age distribution of hospitalizations is as follows: 1,212 (68.1%) were ≥65 years of age, 364 (20.5%) were 45-64 years, 194 (10.9%) were 20-44 years, and 9 (0.5%) were <20 years of age. ICU admission was required for 214 hospitalizations; the majority of which were adults ≥65 years of age (124; 57.9%). Of the ICU admissions, 90 (42.1%) had at least one co-morbidity, five (2.3%) had no co-morbidities, and 119 had no information to date. A total of 115 deaths have been reported: 26 with influenza A(H3N2), one with A(H1N1)pdm09, 82 with A(unsubtyped), five with influenza B, and one untyped. More than 85% of the deaths (98/115) were in adults ≥65 years of age, 14 (12.2%) were adults 45-64 years of age, and 3 (2.6%) were 20-44 years of age. Fifty-two (45.2%) 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 18, 69 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*. The majority of cases were influenza A (56.5%). The highest proportion of hospitalisations were in adults ≥65 years of age (40.6%), followed by children 0-4 years of age (21.7%). Of the 17 cases with available data, six cases were admitted to the ICU, three with influenza A(H1N1)pdm09 and three with influenza B; four were ≥65 years of age, one was 45-64 years of age, and one was 5-14 years of age. Two deaths were reported in week 18, both adults ≥65 years of age with influenza A.

To date this season, 4,733 influenza-associated hospitalizations have been reported, of which 89.1% have been influenza A. Of those subtyped (48.8%), influenza A(H3) was the predominant influenza strain. The cumulative proportion of hospitalizations with influenza B continues to increase (10.9% in week 18). Age information was available for 4,730 cases, and the age distribution is as follows: 2,518 (53.2%) were ≥65 years of age; 789 (16.7%) were 45-64 years of age; 429 (9.1%) were 20-44 years of age; 40 (0.8%) were 15-19 years of age; 228 (4.8%) were 5-14 years; and 726 (15.3%) were 0-4 years of age. Of the 1,293 cases with available data, there have been 204 hospitalisations for which admission to an ICU was required; the highest proportions have been in adults 45-64 years of age, followed by adults ≥65 years of age (35.8% and 34.3%, respectively). To date, 297 deaths have been reported: 245 adults ≥65 years of age, 35 adults 45-64 years; 11 adults 20-44 years, one child 5-14 years of age, 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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http://www.phac-aspc.gc.ca/fluwatch/.../index-eng.php

Pathfinder · #32 May 17th, 2013, 05:07 PM

FluWatch report: May 5 to May 11, 2013 (Week 19)

Posted 2013-05-17For readers interested in the PDF version, the document is available for downloading or viewing:
FluWatch report: May 5 to May 11, 2013 (Week 19) (PDF Version - 113 KB - 8 pages)

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Overall Summary

Influenza activity in Canada continued its slow decline in week 19, with the percentage of laboratory tests positive for influenza at 8.6%. Influenza B was the predominant strain, but detections continued to decrease.
Detections of rhinovirus and parainfluenza continued to increase slowly, while detections of most other respiratory viruses decreased in week 19.
The ILI consultation rate decreased slightly, but was above the expected range. Fewer regions reported localized activity compared to the previous week.

Influenza Activity (geographic spread) and Outbreaks

In week 19, five regions in Ontario reported localized activity and 28 regions reported sporadic activity. The number of regions reporting widespread or localized activity decreased compared to the previous week (Figures 1 and 2). Three new influenza outbreaks were reported: one in a long-term-care facility and two in other facilities or communities (Figure 3).
Figure 1. Map of overall Influenza activity level by province and territory,
Canada, Week 19

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 overall percentage of positive influenza tests decreased slightly compared to recent weeks, from 9.8% in week 18 to 8.6% in week 19. Detections of influenza B decreased for the third consecutive week, and represented 86.5% of total positive influenza detections in week 19 (Figure 4). Among the influenza viruses detected in week 19 (n=229), 13.5% were positive for influenza A viruses [of which 41.9% were A(H1N1)pdm09, 19.4% were A(H3), and 38.7% were A(unsubtyped)] (Table 1). Cumulative influenza virus detections by type/subtype to date are as follows: 85.9% influenza A [34.4% A(H3), 4.6% A(H1N1)pdm09 and 60.9% A(unsubtyped)] and 14.1% influenza B (Table 1).
Detailed information on age and type/subtype has been received for 26,985 cases to date this season (Table 2). The proportion of cases by age group is as follows: 14.9% <5 years; 10.5% between 5-19 years; 16.4% between 20-44 years; 17.5% between 45-64 years of age; 40.7% ≥65 years.

The percentage of positive tests for rhinovirus decreased slightly from 16.5% in week 18 to 15.8% in week 19, but has been slowly increasing since week 01. The percentage of positive tests for parainfluenza (7.4%) increased, continuing its gradual increase over the past 11 weeks. The percentage of tests positive for respiratory syncytial virus (RSV) (3.1%) continued its decline from a peak in week 08. The percentage of positive tests for human metapneumovirus (hMPV) (4.2%) has been decreasing slowly since week 14. The percentage of positive tests for coronavirus (2.3%) increased in week 19 after a slow decline from week 04 to 18 (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 (May 5 to May 11, 2013)						Cumulative (August 26, 2012 to May 11, 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	4	0	1	1	2	11	1910	0	1450	219	241	405
AB	7	0	2	4	1	36	2354	0	1769	441	144	786
SK	0	0	0	0	0	13	836	0	476	73	287	298
MB	1	0	1	0	0	16	658	0	79	10	569	100
ON	9	0	2	5	2	34	8257	0	3780	374	4103	881
QC	5	0	0	1	4	77	9802	0	546	36	9220	1846
NB	4	0	0	2	2	11	1863	0	771	73	1019	71
NS	0	0	0	0	0	0	388	0	165	8	215	7
PE	0	0	0	0	0	0	116	0	76	9	31	1
NL	1	0	0	0	1	0	718	0	152	0	566	16
Canada	31	0	6	13	12	198	26902	0	9264	1243	16395	4411

**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 (May 5 to May 11, 2013)					Cumulative (August 26, 2012 to May 11, 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	2	0	1	1	24	3127	333	1166	1628	901
5-19	1	1	0	0	21	1687	95	825	767	1142
20-44	4	1	0	3	19	3661	478	1539	1644	764
45-64	2	1	1	0	23	3956	443	1563	1950	754
65+	4	0	0	4	26	10140	163	4165	5812	853
Unknown	0	0	0	0	0	164	20	143	1	1
Total	13	3	2	8	113	22735	1532	9401	11802	4415

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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 1251 influenza viruses. The 603 influenza A(H3N2) viruses were antigenically similar to the vaccine strain A/Victoria/361/2011 and the 194 A(H1N1)pdm09 viruses were antigenically similar to the vaccine strain A/California/07/09. Among the influenza B viruses, 356 were antigenically similar to the vaccine strain B/Wisconsin/01/2010 (Yamagata lineage) and 98 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 =1251

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 1223 influenza viruses for resistance to oseltamivir, and 1221 influenza viruses for resistance to zanamivir. Among these, one A(H3N2) virus was resistant to oseltamivir and zanamivir. A total of 1210 influenza A viruses were tested for amantadine resistance and all but one 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)	595	1 (0.2%)	596	1 (0.2%)	980	979 (99.9%)
A (H1N1)	199	0	196	0	230	230 (100%)
B	429	0	429	0	NA ^*	NA ^*
TOTAL	1223	1 (0.1%)	1221	1 (0.1%)	1210	1209 (99.9%)

Influenza-like Illness (ILI) Consultation Rate

The national influenza-like-illness (ILI) consultation rate decreased from 18.3 ILI consultations per 1,000 patient visits in week 18 to 16.1 / 1,000 in week 19, and is above the expected range (Figure 7). In week 19, the highest consultation rate was observed in children 5-19 years of age (33.1/1,000).
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)

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Severe Respiratory Illness Surveillance

Paediatric Influenza Hospitalizations and Deaths (IMPACT)

In week 19, 11 laboratory-confirmed influenza-associated paediatric (≤16 years of age) hospitalizations were reported by the Immunization Monitoring Program Active (IMPACT) network, compared to 16 in week 18. All of the cases reported in week 19 were identified with influenza B. The age distribution is as follows: two cases 0-5 months of age, two 6-23 months of age, four 2-4 years of age, and three 5-9 years of age. Four cases were admitted to an intensive care unit (ICU) during week 19, one child 0-5 months of age, one 6-23 months of age, one 2-4 years of age and one 5-9 years of age; all with influenza B. No deaths were reported in week 19.

Since the start of the 2012-13 season, a total of 863 influenza-associated paediatric hospitalizations have been reported by the IMPACT network: 621 (72.0%) with influenza A [of which 120 (19.3%) were A(H3N2), 25 (4.0%) were A(H1N1)pdm09 and the remaining 476 were A(unsubtyped); and 242 (28.0%) with influenza B. The distribution of cases by age group is as follows: 159 (18.4%) <6 months of age; 200 (23.2%) age 6-23 months; 247 (28.6%) age 2-4 years; 186 (21.6%) age 5-9 years; and 71 (8.2%) age 10-16 years. Of the 863 cases, 94 (10.9%) were admitted to the ICU. Of the 72 ICU admissions with available data, 62 (86.1%) cases had at least one underlying condition. One death has been reported to date this season in a child 6-23 months of age with an underlying condition, with influenza B.

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)

Active surveillance of laboratory-confirmed influenza-associated adult (≥16 years of age) hospitalizations reported by the PHAC/CIHR Influenza Research Network (PCIRN) Serious Outcomes Surveillance (SOS) network has concluded for the 2012-13 influenza season. However, the PCIRN-SOS network will continue to report limited data on laboratory-confirmed cases of influenza. In week 19, 13 hospitalizations were reported from 14 of the 17 PCIRN sites: 12 were cases of influenza B and one case of influenza A. Nine cases were ≥65 years of age, one was 45-64 years, and one was <20 years of age. One ICU admission and no deaths were reported in week 19.

Cumulative data for the season to date includes data from active surveillance from November 4, 2012 to April 30, 2013 and data from passive surveillance since May 1, 2013. The cumulative number of cases reported by the PCIRN-SOS network was 1,792 influenza-associated adult hospitalizations: 90.5% with influenza A [of which 310 were A(H3N2), 19 were A(H1N1)pdm09, and 1292 were A(unsubtyped)]; 125 with influenza B, and the type has not been reported for 46 cases. The age distribution of hospitalizations is as follows: 1221 (68.1%) were ≥65 years of age, 365 (20.4%) were 45-64 years, 194 (10.8%) were 20-44 years, and 10 (0.6%) were <20 years of age. ICU admission was required for 215 hospitalizations; the majority of which were adults ≥65 years of age (125; 58.1%). 115 deaths have been reported: 26 with influenza A(H3N2), one with A(H1N1)pdm09, 82 with A(unsubtyped), 5 with influenza B, and one untyped. More than 85% of the deaths (98/115) were in adults ≥65 years of age, 12.2 (14%) were adults 45-64 years of age, and 3 (2.6%) were 20-44 years of age.

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 19, 44 laboratory-confirmed influenza-associated hospitalizations were reported from participating provinces and territories^*. For the first time during the 2012-13 season, the majority of cases were influenza B (77.3%). The highest proportion of hospitalisations were in adults ≥65 years of age (40.9%), followed by children 0-4 years of age (22.7%). Of the 21 cases with available data, three cases were admitted to the ICU, all with influenza A(unsubtyped); two were ≥65 years of age and one was 45-64 years of age. One death was reported in week 19, an adult ≥65 years of age with influenza B.

To date this season, 4,763 influenza-associated hospitalizations have been reported, of which 88.7% have been influenza A. Of those subtyped (48.9%), influenza A(H3) was the predominant influenza strain. The cumulative proportion of hospitalizations with influenza B continues to increase (11.3% in week 19). Age information was available for 4,760 cases, and the age distribution is as follows: 2,529 (53.1%) were ≥65 years of age; 794 (16.7%) were 45-64 years of age; 429 (9.0%) were 20-44 years of age; 40 (0.8%) were 15-19 years of age; 230 (4.8%) were 5-14 years; and 738 (15.5%) were 0-4 years of age. Of the 1,300 cases with available data, there have been 213 hospitalisations for which admission to an ICU was required; the highest proportions have been in adults 45-64 years of age, followed by adults ≥65 years of age (35.4% and 34.4%, respectively). To date, 298 deaths have been reported: 246 adults ≥65 years of age, 35 adults 45-64 years; 11 adults 20-44 years, one child 5-14 years of age, and 5 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