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EuroFlu - Weekly Electronic Bulletin - Week 2 : 07/01/2013-13/01/2013 - 18 January 2013, Issue N? 471 (edited): H1N1pdm09 were 84% of typed A viruses
[Source: EuroFlu, full page: (LINK). Edited.]
EuroFlu - Weekly Electronic Bulletin - Week 2 : 07/01/2013-13/01/2013 - 18 January 2013, Issue N? 471
Large variation in influenza activity across the WHO European Region
Summary, week 2/2013
For a description of influenza surveillance in the WHO European Region see below.
Virological surveillance for influenza
The number of specimens testing positive for influenza in the Region continues to rise, mainly due to increasing detections in the western part of the Region.
Overall, a total of 3495 specimens tested positive for influenza in week 02/2013, the majority of which, 2532 (72%), were influenza A (Fig. 1).
The proportion of influenza A(H1N1)pdm09 viruses relative to A(H3N2) continues to increase.
In week 2, among 1363 influenza A viruses subtyped, 1151 (84%) were A(H1N1)pdm09 while 212 (16%) were A(H3N2)(Fig. 2a).
This presents a very different picture from the 2011/2012 influenza season when A(H1N1)pdm09 detections were rare.
In the 19 countries testing 20 or more sentinel specimens, influenza positivity ranged from 11% to 68%, with a median of 45% (mean: 44%).
Since the beginning of the season (week 40/2012), 12,247 influenza viruses from sentinel and non-sentinel sources have been typed: 8250 (67%) were influenza A and 3997 (33%) influenza B (Fig. 2b).
Of the influenza A viruses, 4475 were subtyped: 2945 (66%) as A(H1N1)pdm09and 1530 (34%) as A(H3N2).
In addition, since week 40/2012, the lineage has been determined for 497 influenza B viruses: 454 (91%) belonged to the B/Yamagata lineage and 43 (9%) to B/Victoria.
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Current circulation of influenza viruses varies considerably across the Region.
As in the previous weeks, influenza A (mainly A(H1N1)pdm09)has been reported to be the dominant virus in northern and central Europe, in parts of the Russian Federation and in Turkey (Map 1); while influenza B is reported as the dominant virus in some countries in the southern and western part of the Region. In between these areas, co-circulation of A(H1N1)pdm09, A(H3N2) and influenza B is being reported.
Virus strain characterizations
For the 2012/2013 northern hemisphere influenza season, WHO recommends inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (from the B/Yamagata lineage) viruses in vaccines (see more at WHO web site). The majority of characterized viruses from the WHO European Region have been similar to these vaccine viruses.
Since week 40/2012, 179 influenza viruses characterized antigenically by 8 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania, the Russian Federation, Switzerland) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3).
10 countries (Austria, Belgium, Denmark, Finland, Germany, Norway, Portugal, Spain, Sweden, Switzerland) have characterized 140 influenza viruses genetically (Fig. 4).
# Included in the WHO-recommended composition of influenza virus vaccines for use in the 2012/2013 northern hemisphere influenza season.
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013 southern hemisphere influenza season.
Monitoring of susceptibility to antiviral drugs
Since week 40/2012, 7 countries (Denmark, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom) have screened 133 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 63 influenza A(H3N2), 43 A(H1N1)pdm09 and 27 influenza B viruses showed susceptibility to both drugs.
The 14 influenza A(H3N2) and 5 influenza A(H1N1)pdm09 viruses screened for susceptibility to adamantanes were found to be resistant.
Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)
ILI and ARI consultation rates are now starting to increase in the eastern part the Region (Map 4), however,intensity remains low in this area (Map 2). In most of the northern and western parts of the Region and Israel, consultation rates for ILI and ARI continue to increase (Map 4), and are above established seasonal thresholdsin several countries (see Country data and graphs for individual country data). In addition, an increasing number of the western countries are reporting regional or widespread circulation of influenza in week 02/2013 compared to the previous week (Map 3).
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Concurrent with increasing consultation rates for ILI and ARI, the number of influenza detections from sentinel outpatient clinics is gradually increasing, mainly owing to detections in western Europe.
Overall, 1671 specimens were tested, of which 648 (39%) were positive for influenza in week 02/2013; similar to week 01/2013 (Fig. 5).
Of the 648 positive specimens from sentinel sources, influenza A was detected in 58% of the samples (Fig. 6a), a slight increase in comparison to the previous weeks where influenza A and B have been detected in equal proportions. Fig. 6b gives a detailed overview of cumulative influenza virus detections by type and subtype since week 40/2012. Click here for a detailed overview in a table format.
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Hospital surveillance for SARI
Hospitalizations due to SARI have increased slightly over the past few weeks along with an increase in the proportion of respiratory specimens from patients testing positive for influenza (Fig. 7). Overall, the great majority of cases reported have been in the age-group 0?4 years (see Country data and graphsfor individual country data).
In the past few weeks, only sporadic influenza detections have been reported among SARI cases (Fig. 7),reflecting an overall low influenza activity in countries reporting on SARI hospitalizations.
In week 02/2013, 6 countries (Belarus, Belgium, Georgia, Kyrgyzstan, Romania and the Russian Federation) detected a total of 28 influenza viruses among 200 specimens tested (Fig. 8a). Since week 40/2012, 2018 SARI specimens have been collected and tested for influenza. Click here for a detailed overview in table format.
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Among the countries reporting on severe influenza in hospitals to the European Centre for Disease Prevention and Control (ECDC), a higher number of influenza detections has been reported compared to countries reporting on SARI (most of which are in the eastern part of the Region), reflecting higher levels of influenza activity in the western part of the Region.
To date, A(H1N1)pdm09, A(H3N2) and influenza B have been detected among hospitalized patients.
For more information on surveillance of confirmed hospitalized influenza, please see ECDC?s Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
The EUROMOMO mortality monitoring system
Pooled analysis for week 2/2013 did not show any excess of all-cause mortality for this season so far. However, 2 out of 15 reporting countries saw a clear increase of mortality in the elderly (65 years and above). For more information about the EUROMOMO mortality monitoring system please click here)
Description of influenza surveillance
Most of the 53 Member States of the WHO European Region monitor influenza activity through surveillance of ILI and/or ARI in primary care clinics, with some countries also conducting hospital-based surveillance for severe disease. Surveillance data in the Region are collected from sentinel and non-sentinel systems. Sentinel data come from a network of designated clinicians who routinely and systematically collect respiratory specimens from ILI, ARI or SARI cases according to standard case definitions. Non-sentinel data come from a variety of other sources, including community outbreaks, general practitioners and hospitals that are not part of the sentinel surveillance system for influenza and may not use a standard case definition for ILI, ARI or SARI. The EuroFlu bulletin collates and interprets epidemiological and virological data from the different surveillance systems in the Region, to provide information on the timing of the influenza season, the spread of influenza, the prevalence and characteristics of circulating influenza viruses according to influenza type and subtype (A(H3N2) and A(H1N1)pdm09) or lineage (B/Victoria of B/Yamagata), and severity. In addition, influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic and genetic similarity to the viruses included in the seasonal influenza vaccine and the prevalence of mutations that affect pathogenicity or are associated with reduced susceptibility to antiviral drugs.
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Country comments (where available)
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EuroFlu - Weekly Electronic Bulletin - Week 2 : 07/01/2013-13/01/2013 - 18 January 2013, Issue N? 471
Large variation in influenza activity across the WHO European Region
Summary, week 2/2013
- Consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) are now increasing in almost all countries in the Region.
- However, influenza activity is still largely limited to the western part of the Region, where widespread transmission is being reported by most countries currently.
- While influenza A(H1N1)pdm09, A(H3N2) and type B viruses are circulating in the Region, the proportion of influenza A(H1N1)pdm09 continues to increase, relative to influenza B and A(H3N2), and accounts for 84% of influenza A viruses subtyped.
- The number of reported hospitalizations due to severe acute respiratory infection (SARI) is increasing slowly along with a rising proportion of patients testing positive for influenza.
For a description of influenza surveillance in the WHO European Region see below.
Virological surveillance for influenza
The number of specimens testing positive for influenza in the Region continues to rise, mainly due to increasing detections in the western part of the Region.
Overall, a total of 3495 specimens tested positive for influenza in week 02/2013, the majority of which, 2532 (72%), were influenza A (Fig. 1).
In week 2, among 1363 influenza A viruses subtyped, 1151 (84%) were A(H1N1)pdm09 while 212 (16%) were A(H3N2)(Fig. 2a).
This presents a very different picture from the 2011/2012 influenza season when A(H1N1)pdm09 detections were rare.
In the 19 countries testing 20 or more sentinel specimens, influenza positivity ranged from 11% to 68%, with a median of 45% (mean: 44%).
Since the beginning of the season (week 40/2012), 12,247 influenza viruses from sentinel and non-sentinel sources have been typed: 8250 (67%) were influenza A and 3997 (33%) influenza B (Fig. 2b).
Of the influenza A viruses, 4475 were subtyped: 2945 (66%) as A(H1N1)pdm09and 1530 (34%) as A(H3N2).
In addition, since week 40/2012, the lineage has been determined for 497 influenza B viruses: 454 (91%) belonged to the B/Yamagata lineage and 43 (9%) to B/Victoria.
(?)
Current circulation of influenza viruses varies considerably across the Region.
As in the previous weeks, influenza A (mainly A(H1N1)pdm09)has been reported to be the dominant virus in northern and central Europe, in parts of the Russian Federation and in Turkey (Map 1); while influenza B is reported as the dominant virus in some countries in the southern and western part of the Region. In between these areas, co-circulation of A(H1N1)pdm09, A(H3N2) and influenza B is being reported.
Virus strain characterizations
For the 2012/2013 northern hemisphere influenza season, WHO recommends inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Victoria/361/2011 (H3N2)-like and B/Wisconsin/1/2010-like (from the B/Yamagata lineage) viruses in vaccines (see more at WHO web site). The majority of characterized viruses from the WHO European Region have been similar to these vaccine viruses.
Since week 40/2012, 179 influenza viruses characterized antigenically by 8 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania, the Russian Federation, Switzerland) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3).
10 countries (Austria, Belgium, Denmark, Finland, Germany, Norway, Portugal, Spain, Sweden, Switzerland) have characterized 140 influenza viruses genetically (Fig. 4).
* Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013 southern hemisphere influenza season.
Monitoring of susceptibility to antiviral drugs
Since week 40/2012, 7 countries (Denmark, Germany, the Netherlands, Norway, Spain, Sweden and the United Kingdom) have screened 133 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 63 influenza A(H3N2), 43 A(H1N1)pdm09 and 27 influenza B viruses showed susceptibility to both drugs.
The 14 influenza A(H3N2) and 5 influenza A(H1N1)pdm09 viruses screened for susceptibility to adamantanes were found to be resistant.
Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)
ILI and ARI consultation rates are now starting to increase in the eastern part the Region (Map 4), however,intensity remains low in this area (Map 2). In most of the northern and western parts of the Region and Israel, consultation rates for ILI and ARI continue to increase (Map 4), and are above established seasonal thresholdsin several countries (see Country data and graphs for individual country data). In addition, an increasing number of the western countries are reporting regional or widespread circulation of influenza in week 02/2013 compared to the previous week (Map 3).
(?)
Concurrent with increasing consultation rates for ILI and ARI, the number of influenza detections from sentinel outpatient clinics is gradually increasing, mainly owing to detections in western Europe.
Overall, 1671 specimens were tested, of which 648 (39%) were positive for influenza in week 02/2013; similar to week 01/2013 (Fig. 5).
(?)
Hospital surveillance for SARI
Hospitalizations due to SARI have increased slightly over the past few weeks along with an increase in the proportion of respiratory specimens from patients testing positive for influenza (Fig. 7). Overall, the great majority of cases reported have been in the age-group 0?4 years (see Country data and graphsfor individual country data).
In week 02/2013, 6 countries (Belarus, Belgium, Georgia, Kyrgyzstan, Romania and the Russian Federation) detected a total of 28 influenza viruses among 200 specimens tested (Fig. 8a). Since week 40/2012, 2018 SARI specimens have been collected and tested for influenza. Click here for a detailed overview in table format.
(?)
Among the countries reporting on severe influenza in hospitals to the European Centre for Disease Prevention and Control (ECDC), a higher number of influenza detections has been reported compared to countries reporting on SARI (most of which are in the eastern part of the Region), reflecting higher levels of influenza activity in the western part of the Region.
To date, A(H1N1)pdm09, A(H3N2) and influenza B have been detected among hospitalized patients.
For more information on surveillance of confirmed hospitalized influenza, please see ECDC?s Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
The EUROMOMO mortality monitoring system
Pooled analysis for week 2/2013 did not show any excess of all-cause mortality for this season so far. However, 2 out of 15 reporting countries saw a clear increase of mortality in the elderly (65 years and above). For more information about the EUROMOMO mortality monitoring system please click here)
Description of influenza surveillance
Most of the 53 Member States of the WHO European Region monitor influenza activity through surveillance of ILI and/or ARI in primary care clinics, with some countries also conducting hospital-based surveillance for severe disease. Surveillance data in the Region are collected from sentinel and non-sentinel systems. Sentinel data come from a network of designated clinicians who routinely and systematically collect respiratory specimens from ILI, ARI or SARI cases according to standard case definitions. Non-sentinel data come from a variety of other sources, including community outbreaks, general practitioners and hospitals that are not part of the sentinel surveillance system for influenza and may not use a standard case definition for ILI, ARI or SARI. The EuroFlu bulletin collates and interprets epidemiological and virological data from the different surveillance systems in the Region, to provide information on the timing of the influenza season, the spread of influenza, the prevalence and characteristics of circulating influenza viruses according to influenza type and subtype (A(H3N2) and A(H1N1)pdm09) or lineage (B/Victoria of B/Yamagata), and severity. In addition, influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic and genetic similarity to the viruses included in the seasonal influenza vaccine and the prevalence of mutations that affect pathogenicity or are associated with reduced susceptibility to antiviral drugs.
(?)
Country comments (where available)
- Czech Republic: Up to end of week 2/2013 a cumulative total of 80 severe influenza patients with laboratory-confirmed influenza were reported by intensive and resuscitation care units including 11 deaths.
- Republic of Moldova: This 2nd sentinel week in one sentinel sample was detected ARN Influenza type B and in one non-sentinel SARI sample was detected ARN Parainfluenza virus type 3.
- Scotland: All Influenza A (H3N2) and A(H1N1)pdm09 samples sequenced to date match the respective vaccine strains. Of the Influenza B samples for which the lineage has been determined 75% could be attributed to Yamagata lineage and 25% to Victoria lineage.
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