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EuroFlu - Weekly Electronic Bulletin - Week 50 : 10/12/2012-16/12/2012 - 21 December 2012, Issue N? 467 (edited): 121/190 A(H1N1)pdm09
[Source: EuroFlu, full page: (LINK). Extract, edited.]
EuroFlu - Weekly Electronic Bulletin - Week 50 : 10/12/2012-16/12/2012 - 21 December 2012, Issue N? 467
The influenza season has begun in the WHO European Region
Summary, week 50/2012
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 has increased steadily in the past weeks, mainly due to influenza viruses detected in Norway, France and the United Kingdom.
Overall, a total of 577 specimens tested positive for influenza in week 50/2012: 338 were type A and 239 were type B.
Of the influenza A viruses, 191 were subtyped: 70 as A(H3N2) and 121 as A(H1N1)pdm09 (Fig. 1).
Since week 40/2012, influenza A and influenza B viruses have been detected in almost equal proportions, and 1843 influenza viruses from sentinel and non-sentinel sources have been typed: 1073 (58%) were influenza A and 770 (42%) influenza B.
Of the influenza A viruses 669 were subtyped: 351 (52%) as A(H3N2) and 318 (48%) as A(H1N1)pdm09 (Fig 2).
(?)
During week 50/2012, Denmark, Germany, Sweden and the United Kingdom (Scotland) reported dominant viruses as influenza A, with Belgium, Luxembourg and the United Kingdom (Wales and Northern Ireland) reporting influenza B as the dominant type (Map 1).
It is too early to assess which influenza viruses will dominate this season as the number of detections is still 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, 54 influenza viruses characterized antigenically by 6 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania) have 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 60 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 26 influenza A(H3N2) viruses, 27 A(H1N1)pdm09 viruses and 7 influenza B viruses showed susceptibility to oseltamivir and zanamivir.
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 are still low throughout the WHO European Region (Map 2), with three countries (Norway, Sweden and the United Kingdom (England)) reported regional or widespread circulation of influenza (Map 3), and 17 of 41 reported increasing trends (Map 4).
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The influenza-positivity rate among ILI and ARI cases from sentinel sources increased in comparison with previous weeks, along with the number of specimens tested: 171 (15.8%) of 1082 specimens tested positive for influenza this week (Fig. 5).
Influenza-positive cases were reported mainly by countries in western Europe, with more than half of the positive samples reported by the United Kingdom, France, Germany and Norway.
Of the 1082 specimens from sentinel sources, 91 tested positive for influenza A and 80 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 continue to be stable and at pre-season levels in the 10 countries reporting this week (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine). Most cases occurred in the age group 0?4 years (Fig. 7).
To date, only a few influenza detections have been reported by the hospitals participating in SARI surveillance, similar to the situation in outpatient surveillance in these countries.
In week 50, 2 cases tested positive among 122 specimens collected from hospitalized SARI cases in 8 countries (Armenia, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation and Ukraine); the Russian Federation reported 1 SARI case positive for influenza B and Ukraine reported 1 case positive for A(H3N2) (Fig. 8a).
Since week 40/2012, 1305 SARI specimens have been tested for influenza, with only 10 cases being positive for influenza (Fig. 8b). Click here for a detailed overview in table format.
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For the countries reporting to the European Centre for Disease Prevention and Control (ECDC) on severe influenza in hospitals, no cases were reported positive for influenza this week.
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 50 : 10/12/2012-16/12/2012 - 21 December 2012, Issue N? 467
The influenza season has begun in the WHO European Region
Summary, week 50/2012
- The influenza season has begun in the WHO European Region, with growing numbers of countries in different parts of the Region reporting sporadic co-circulation of influenza A(H1N1)pdm09, A(H3N2) and type B viruses, though influenza activity is still at a low level.
- Further, the percentage of influenza-positive sentinel samples has increased over the past two weeks (from 6% to 15.8%) together with the number of specimens tested for influenza, indicating the start of the influenza season.
- The number of reported hospitalizations due to severe acute respiratory infection (SARI) remains similar to that seen in the previous several weeks, with 2 cases associated with confirmed influenza infection, one each of types A and B.
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 has increased steadily in the past weeks, mainly due to influenza viruses detected in Norway, France and the United Kingdom.
Overall, a total of 577 specimens tested positive for influenza in week 50/2012: 338 were type A and 239 were type B.
Of the influenza A viruses, 191 were subtyped: 70 as A(H3N2) and 121 as A(H1N1)pdm09 (Fig. 1).
Of the influenza A viruses 669 were subtyped: 351 (52%) as A(H3N2) and 318 (48%) as A(H1N1)pdm09 (Fig 2).
(?)
During week 50/2012, Denmark, Germany, Sweden and the United Kingdom (Scotland) reported dominant viruses as influenza A, with Belgium, Luxembourg and the United Kingdom (Wales and Northern Ireland) reporting influenza B as the dominant type (Map 1).
It is too early to assess which influenza viruses will dominate this season as the number of detections is still 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, 54 influenza viruses characterized antigenically by 6 countries (Denmark, the United Kingdom (England), Germany, Latvia, Portugal, Romania) have 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 60 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.
The 26 influenza A(H3N2) viruses, 27 A(H1N1)pdm09 viruses and 7 influenza B viruses showed susceptibility to oseltamivir and zanamivir.
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 are still low throughout the WHO European Region (Map 2), with three countries (Norway, Sweden and the United Kingdom (England)) reported regional or widespread circulation of influenza (Map 3), and 17 of 41 reported increasing trends (Map 4).
(?)
The influenza-positivity rate among ILI and ARI cases from sentinel sources increased in comparison with previous weeks, along with the number of specimens tested: 171 (15.8%) of 1082 specimens tested positive for influenza this week (Fig. 5).
Influenza-positive cases were reported mainly by countries in western Europe, with more than half of the positive samples reported by the United Kingdom, France, Germany and Norway.
(?)
Hospital surveillance for SARI
Hospitalizations due to SARI continue to be stable and at pre-season levels in the 10 countries reporting this week (Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine). Most cases occurred in the age group 0?4 years (Fig. 7).
In week 50, 2 cases tested positive among 122 specimens collected from hospitalized SARI cases in 8 countries (Armenia, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation and Ukraine); the Russian Federation reported 1 SARI case positive for influenza B and Ukraine reported 1 case positive for A(H3N2) (Fig. 8a).
Since week 40/2012, 1305 SARI specimens have been tested for influenza, with only 10 cases being positive for influenza (Fig. 8b). Click here for a detailed overview in table format.
(?)
For the countries reporting to the European Centre for Disease Prevention and Control (ECDC) on severe influenza in hospitals, no cases were reported positive for influenza this week.
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)
- Norway: The number of influenza virus detections increased considerably in week 50. There appears to be local variation in the occurrence of A(H1N1)pdm09, A(H3N2), and B/Yamagata lineage viruses. B/Victoria lineage viruses have been very rare. None of the three circulating viruses qualifies for predominance or co-predominance.
- Republic of Moldova: This 50th Influenza Surveillance week were tested 28 specimens: 2 were positive for DNA Adenovirus, 4 - positive for RNA hRSV and 1 sample was positive for RNA Parainfluenza type 3.
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