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EuroFlu - Weekly Electronic Bulletin - Week 12 : 17/03/2014-23/03/2014 - 28 March 2014, Issue No. 523: More ICU patients diagnosed w/ H1N1pdm09 this season

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  • EuroFlu - Weekly Electronic Bulletin - Week 12 : 17/03/2014-23/03/2014 - 28 March 2014, Issue No. 523: More ICU patients diagnosed w/ H1N1pdm09 this season

    [Source: EuroFlu, full page: (LINK). Edited.]

    EuroFlu - Weekly Electronic Bulletin - Week 12 : 17/03/2014-23/03/2014 - 28 March 2014, Issue No. 523

    Low influenza activity reported in most European countries

    Summary, week 12/2014
    • Clinical consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) returned to pre-season or below baseline levels in most of the countries in the WHO European Region.
    • This is consistent with the decline in the percentage of ILI and ARI sentinel specimens testing positive for influenza.
    • Based on the results of outpatient and hospital surveillance, influenza A(H1N1)pdm09 and A(H3N2) viruses continued to co-circulate in the Region, with very few influenza B detections having been reported during this season.

    The EuroFlu bulletin describes and comments on influenza activity in the 53 Member States in the WHO European Region to provide information to public health specialists, clinicians and the public on the timing of the influenza season, the spread of influenza, the prevalence and characteristics of circulating viruses (type, subtype and lineage) and severity.

    For a description of influenza surveillance in the WHO European Region see below.

    Virological surveillance for influenza

    During week 12/2014, both the total number of specimens tested for influenza and the influenza positivity rate decreased from those in previous weeks: 13 193 specimens from sentinel and non-sentinel sources were tested for influenza, 2398 (18%) of which were positive: 2212 (92%) influenza A and 186 (8%) influenza B (Fig. 1 and 2).


    Influenza A has remained the dominant virus type in circulation across the Region since the start of weekly monitoring in week 40/2013.

    Of the 1342 influenza A viruses that were subtyped during week 12/2014, 594 (44%) were A(H1N1)pdm09 and 748 (56%) A(H3N2) (Fig. 2a). Influenza B accounted for a small proportion of influenza detections, which remained steady over the past weeks.

    Since week 40/2013, sentinel and non-sentinel sources have yielded 37 583 influenza detections: 35 897 (95%) were influenza A and 1686 (5%) influenza B viruses (Fig. 2b). Of the 25 143 influenza A viruses that have been subtyped, 14 835 (59%) were A(H1N1)pdm09 and 10 308 (41%) were A(H3N2).

    In addition, the lineage of 169 influenza B viruses has been determined: 155 (92%) belonged to the B/Yamagata lineage (the lineage of the B virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 14 (8%) to the B/Victoria lineage.



    Of the 41 countries that reported data on the dominant type of influenza virus, 26 reported influenza A as dominant in week 12/2014.

    Turkey was the only country reporting influenza B as dominant (Map 1 and country table).

    In countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in 14 countries (Belgium, Croatia, Georgia, Germany, Hungary, Ireland, Lithuania, Luxembourg, Romania, the Russian Federation, Slovenia, Spain, the former Yugoslav Republic of Macedonia and Ukraine), while only 4 Member States (Bosnia and Herzegovina, Greece, Norway and the United Kingdom (Scotland and Wales)) reported A(H1N1)pdm09 as dominant. 3 countries (France, Latvia and the Netherlands) reported A(H1N1)pdm09 and A(H3N2) as co-dominant.

    Virus strain characterizations

    Circulating influenza viruses are assessed each season for their antigenic and genetic characteristics, to determine the extent of their antigenic similarity to the viruses included in the seasonal influenza vaccine, and determine the prevalence of mutations that affect pathogenicity or are associated with susceptibility to antiviral drugs.

    For the 2013/2014 northern hemisphere influenza season, WHO recommended inclusion of A/California/7/2009 (H1N1)pdm09-like, A/Texas/50/2012 (H3N2)-like and B/Massachusetts/2/2012-like (Yamagata lineage) viruses in vaccines (see the WHO headquarters web site).

    The WHO Consultation on the Composition of Influenza Virus Vaccines for the Northern Hemisphere 2014?2015 took place in week 7/2014, and the WHO expert group recommended no change from the vaccine composition for the 2013?2014 season. (see the WHO headquarters web site).

    Since week 40/2013, 1406 influenza viruses characterized antigenically by 14 countries (the Czech Republic, Denmark, Finland, Germany, Ireland, Latvia, the Netherlands, Norway, Portugal, Romania, the Russian Federation, Slovakia, Switzerland and the United Kingdom (England, Scotland)) corresponded with the viruses recommended by WHO for inclusion in the current northern hemisphere seasonal influenza vaccine (Fig. 3).

    14 countries (Belgium, the Czech Republic, Denmark, Finland, Germany, Greece, Ireland, the Netherlands, Norway, Portugal, the Russian Federation, Spain, Sweden and Switzerland) have characterized 780 influenza viruses genetically (Fig. 4).


    # Included in the WHO-recommended composition of influenza virus vaccines for use in the 2013/2014 northern hemisphere influenza season.

    * Included in the WHO-recommended composition of influenza virus vaccines for use in the 2014 southern hemisphere influenza season.

    Monitoring of susceptibility to antiviral drugs

    Since week 40/2013, 9 countries (Greece, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, the Russian Federation and the United Kingdom (England)) have screened 885 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

    Of the 740 A(H1N1)pdm09 viruses tested, 731 showed susceptibility to both drugs; 9 viruses carried the neuraminidase H275Y amino acid substitution, causing resistance to oseltamivir.

    Of these viruses, 8 were detected in the United Kingdom in hospitalized patients, most of whom were treated with neuraminidase inhibitors, and 1 virus from Switzerland was detected in a hospitalized immunocompromised patient treated with oseltamivir.

    Of the 204 influenza A(H3N2) viruses tested, 203 showed susceptibility to both drugs. The remaining virus, detected in the United Kingdom in a hospitalized immunocompromised patient treated with oseltamivir, carried the neuraminidase E119V amino acid substitution, and showed reduced inhibition by oseltamivir but normal inhibition by zanamivir. All 38 influenza B viruses tested showed susceptibility to both oseltamivir and zanamivir.

    So far, there is no indication of increased resistance to the neuraminidase inhibitors during the winter of 2013?2014. All 130 influenza A(H1N1)pdm09 and 85 influenza A(H3N2) viruses screened for susceptibility to adamantanes were found to be resistant.

    Outpatient surveillance for influenza-like illness (ILI) and/or acute respiratory infection (ARI)

    During week 12/2014, most European countries reported low-intensity influenza activity (Map 2), with very few reporting increasing trends (Map 4). As to geographic spread, influenza activity varied between sporadic and regional (Map 3).

    During week 12/2014, consultation rates stabilized in most countries in the Region. Of the 22 countries with established national thresholds, the rates returned to or below the threshold levels in most. In a number of northern and western countries (the Czech Republic, Denmark, Germany, Latvia, Lithuania, Luxembourg, the Netherlands, Norway, Slovakia, Switzerland and the United Kingdom (England)), consultation rates have remained very low since the beginning of the season (mostly below the threshold) and much lower than last season.


    The percentage of positive sentinel ILI/ARI specimens decreased slightly in comparison with the previous week and remained lower than at the same period last season (Fig. 5).


    During week 12/2014, 295 (30%) of the 970 specimens collected from sentinel sources tested positive for influenza; the majority contained influenza A(H3N2) virus (Fig. 6a), similarly to the previous weeks. The number of influenza B detections remained low but has slightly increased over the last several weeks. Click here for a detailed overview in a table format.


    Hospital surveillance for SARI

    For sentinel surveillance of severe disease due to influenza, in week 12/2014 the number of SARI hospitalizations decreased, with most cases reported in those aged 0?4 years. The percentage of SARI patients who tested positive for influenza decreased for the third consecutive week (Fig. 7).


    During week 12/2014, 47 (22%) of the 212 SARI samples collected from sentinel surveillance in Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine tested positive for influenza A, the majority being A(H3N2) (Fig. 8a), in line with the results of sentinel ILI/ARI surveillance. Click here for a detailed overview in table format.


    For week 12/2014, 6 countries (France, Ireland, Romania, Spain, Sweden and the United Kingdom) reported 117 hospitalized laboratory-confirmed influenza cases. Influenza A virus was detected in 113 cases and influenza B virus in 4. Of the hospitalized cases, 67 were admitted to intensive care units (ICUs).

    Since week 40/2013, 7 countries have reported 4232 hospitalized, laboratory-confirmed influenza cases: 4184 (99%) were related to influenza virus type A infection and 48 (1%) to type B virus infection. Of 2853 subtyped influenza A viruses, 2138 (75%) were A(H1N2)pdm09 and 715 (25%) were A(H3N2).

    A higher proportion of A(H1)pdm09 viruses was detected in patients in ICUs (1212 (85%) of 1420 subtyped) than in other wards (926 (65%) of 1433 subtyped). The reasons for these differences have not yet been identified.

    5 countries reported a total of 351 fatal laboratory-confirmed influenza cases; 348 (99%) were associated with influenza virus type A infection and 3 (1%) with type B virus. Of 258 influenza A viruses subtyped from fatal cases, 209 (81%) were A(H1N1)pdm09 and 49 (19%) were A(H3N2).

    The results from SARI surveillance at sentinel hospitals reported to the WHO Regional Office for Europe (EuroFlu) and hospitalized laboratory-confirmed influenza cases reported to the European Centre for Disease Prevention and Control (ECDC) differ in that the former include a higher proportion of influenza A(H3N2) and a lower proportion of influenza A(H1N1)pdm09 than the latter. This pattern is most likely due to the circulation of the different influenza virus subtypes in countries.

    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.

    Respiratory syncytial virus (RSV)

    Based on the data reported by countries on RSV, detections peaked in week 50/2013 and have decreased in all the reporting countries since. This represents a slightly later start than in the previous season (see Country data and graphs for individual country data).

    EuroMOMO (European Mortality Monitoring Project)

    EuroMOMO is a project set up to develop and operate a routine public health mortality monitoring system to detect and measure, on a real-time basis, excess deaths related to influenza and other possible public health threats across 20 European Union (EU) countries.

    Pooled analysis of week data for 12/2014 showed that all-cause mortality was within the normal range for all reporting countries. Results of pooled analysis may vary, depending on which countries are included in the weekly analysis.

    For more information about the EUROMOMO mortality monitoring system please click here.


    Country comments (where available)
    • Republic of Moldova
      • In week 12 were tested 24 samples for influenza viruses: 6 were positive for RNA A(H3N2); 2 samples - RNA hRSV; 2 samples - DNA Adenovirus, and 1 sample was positive for RNA hPiv1.