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EuroFlu - Weekly Electronic Bulletin - Week 52 : 24/12/2012-30/12/2012 - 04 January 2013, Issue N? 469 (edited): higher proportion of H1N1pdm09 than last season
[Source: EuroFlu, full page: (LINK). Edited.]
EuroFlu - Weekly Electronic Bulletin - Week 52 : 24/12/2012-30/12/2012 - 04 January 2013, Issue N? 469
Influenza activity is increasing mainly due to influenza detections in western Europe
Summary, week 52/2012
For a description of influenza surveillance in the WHO European Region see below.
Virological surveillance for influenza
In week 52/2012, the reported number of specimens testing positive for influenza, along with the number of samples tested, was relatively low, due to suboptimal reporting by countries in the eastern part of the Region during the holiday period.
Overall, a total of 844 specimens tested positive for influenza in week 52/2012: 593 were type A and 251 were type B.
Of the influenza A viruses, 194 were subtyped: 55 as A(H3N2) and 139 as A(H1N1)pdm09 (Fig. 1).
Since week 40/2012, influenza A and influenza B viruses had been detected in comparable proportions.
The prevalence of influenza A(H1N1)pdm09 increased in week 52, however; 4068 influenza viruses from sentinel and non-sentinel sources have been typed: 2454 (60%) were influenza A and 1614 (40%) influenza B.
Of the influenza A viruses 1293 were subtyped: 655 (51%) as A(H3N2) and 638 (49%) as A(H1N1)pdm09 (Fig 2).
The proportion of A(H1N1)pdm09 cases is significantly higher than in the same period last season, when these cases, from sentinel and non-sentinel sources, represented less than 5% of total detections.
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In week 52/2012, Denmark, the Czech Republic, Germany and Turkey reported influenza A as the dominant virus type, while Ireland, Luxembourg and Spain reported influenza B as dominant.
France and Switzerland reported influenza A and B as co-dominant (Map 1). It is still too early to assess which influenza viruses will dominate this season as the number of detections remains relatively low.
Virus strain characterizations
In 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 trivalent vaccines (see more at WHO web site).
Since week 40/2012, 81 influenza viruses characterized antigenically by 7 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania, Switzerland) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3). 8 countries (Belgium, Denmark, Finland, Germany, Norway, Portugal, Spain, Sweden) have characterized 91 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 81 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 37 influenza A(H3N2) viruses, 28 A(H1N1)pdm09 viruses and 16 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)
Consultation rates for ILI and ARI remain at low levels throughout most countries in the WHO European Region, but are increasing in some western countries (France, Italy, the Netherlands and Norway) (Map 2).
In addition, a growing number of countries (Belgium, Denmark, Italy, France, the Netherlands, Norway and the United Kingdom (England)) reported regional or widespread circulation of influenza in week 52 (Map 3). Although some countries in eastern Europe and central Asia reported increasing trends in ILI or ARI (Map 4), influenza activity remains low in this part of the Region (Map 2 and Map 3).
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The influenza-positivity rate among ILI and ARI cases from sentinel sources decreased slightly from the previous week: 116 (20%) of 567 specimens tested positive for influenza in week 52 (Fig. 5).
Of the 587 specimens from sentinel sources, 72 tested positive for influenza A and 44 for influenza B (Fig. 6a). 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 remain low in the 8 countries reporting in week 52 (Albania, Belarus, Belgium, Georgia, Kazakhstan, the Republic of Moldova, Serbia and Ukraine) with most cases falling in the group aged 0?4 years (Fig. 7).
In week 52, only 2 countries (Kazakhstan and Ukraine) reported data on specimens tested for influenza. A total of 35 cases was tested, but all were negative (Fig. 8a). Since week 40/2012, 1541 SARI specimens have been collected and tested for influenza with only 13 influenza detections (Fig. 8b). Click here for a detailed overview in table format.
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The countries notifying the European Centre for Disease Prevention and Control (ECDC) of severe influenza in hospitals, reported 12 cases positive for influenza in week 52
For the surveillance of confirmed hospitalized influenza see the Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
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 52 : 24/12/2012-30/12/2012 - 04 January 2013, Issue N? 469
Influenza activity is increasing mainly due to influenza detections in western Europe
Summary, week 52/2012
- Influenza-like illness (ILI) and acute respiratory infection (ARI) consultation rates continue to rise, following a west-to-east progression across the WHO European Region.
- For the second week, reporting of influenza surveillance data was incomplete, due to the holiday period.
- Countries mainly in the western part of the Region reported co-circulation of influenza A(H1N1)pdm09, A(H3N2) and type B viruses.
- The proportion of A(H1N1)pdm09 is considerably higher in comparison with the same time period last season.
- The number of reported hospitalizations due to severe acute respiratory infection (SARI) remains low, with no cases being associated with influenza detection
For a description of influenza surveillance in the WHO European Region see below.
Virological surveillance for influenza
In week 52/2012, the reported number of specimens testing positive for influenza, along with the number of samples tested, was relatively low, due to suboptimal reporting by countries in the eastern part of the Region during the holiday period.
Overall, a total of 844 specimens tested positive for influenza in week 52/2012: 593 were type A and 251 were type B.
Of the influenza A viruses, 194 were subtyped: 55 as A(H3N2) and 139 as A(H1N1)pdm09 (Fig. 1).
The prevalence of influenza A(H1N1)pdm09 increased in week 52, however; 4068 influenza viruses from sentinel and non-sentinel sources have been typed: 2454 (60%) were influenza A and 1614 (40%) influenza B.
Of the influenza A viruses 1293 were subtyped: 655 (51%) as A(H3N2) and 638 (49%) as A(H1N1)pdm09 (Fig 2).
The proportion of A(H1N1)pdm09 cases is significantly higher than in the same period last season, when these cases, from sentinel and non-sentinel sources, represented less than 5% of total detections.
(?)
In week 52/2012, Denmark, the Czech Republic, Germany and Turkey reported influenza A as the dominant virus type, while Ireland, Luxembourg and Spain reported influenza B as dominant.
France and Switzerland reported influenza A and B as co-dominant (Map 1). It is still too early to assess which influenza viruses will dominate this season as the number of detections remains relatively low.
Virus strain characterizations
In 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 trivalent vaccines (see more at WHO web site).
Since week 40/2012, 81 influenza viruses characterized antigenically by 7 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania, Switzerland) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3). 8 countries (Belgium, Denmark, Finland, Germany, Norway, Portugal, Spain, Sweden) have characterized 91 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 81 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 37 influenza A(H3N2) viruses, 28 A(H1N1)pdm09 viruses and 16 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)
Consultation rates for ILI and ARI remain at low levels throughout most countries in the WHO European Region, but are increasing in some western countries (France, Italy, the Netherlands and Norway) (Map 2).
In addition, a growing number of countries (Belgium, Denmark, Italy, France, the Netherlands, Norway and the United Kingdom (England)) reported regional or widespread circulation of influenza in week 52 (Map 3). Although some countries in eastern Europe and central Asia reported increasing trends in ILI or ARI (Map 4), influenza activity remains low in this part of the Region (Map 2 and Map 3).
(?)
The influenza-positivity rate among ILI and ARI cases from sentinel sources decreased slightly from the previous week: 116 (20%) of 567 specimens tested positive for influenza in week 52 (Fig. 5).
(?)
Hospital surveillance for SARI
Hospitalizations due to SARI remain low in the 8 countries reporting in week 52 (Albania, Belarus, Belgium, Georgia, Kazakhstan, the Republic of Moldova, Serbia and Ukraine) with most cases falling in the group aged 0?4 years (Fig. 7).
(?)
The countries notifying the European Centre for Disease Prevention and Control (ECDC) of severe influenza in hospitals, reported 12 cases positive for influenza in week 52
For the surveillance of confirmed hospitalized influenza see the Weekly Influenza Surveillance Overview (WISO) at European Centre for Disease Prevention and Control web site.
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)
- Greece: The first influenza case of the 2012-2013 season was confirmed on Friday 28-Dec-2012. A swab specimen received from a hospitalized 2-year old male, tested positive by real time PCR for influenza A/H3N2 virus.
- Norway: There is a massive media attention on the cases with A(H1N1)pdm09 in Norway at the moment.
- Slovakia: In Slovakia we have in the last week of the year very high decreasing of ILI and ARI because in Slovakia was 3 days holiday (doktors didnt work and also children dont go to school.
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