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EuroFlu - Weekly Electronic Bulletin - Week 11 : 10/03/2014-16/03/2014 - 21 March 2014, Issue No. 522 (edited)

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  • EuroFlu - Weekly Electronic Bulletin - Week 11 : 10/03/2014-16/03/2014 - 21 March 2014, Issue No. 522 (edited)

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


    EuroFlu - Weekly Electronic Bulletin - Week 11 : 10/03/2014-16/03/2014 - 21 March 2014, Issue No. 522

    Low influenza activity in Europe with co-circulation of influenza A(H1N1)pdm09 and A(H3N2)


    Summary, week 11/2014
    • Consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) continue to decline throughout most parts of the WHO European Region, with most countries reporting low intensity during week 11/2014.
    • While the percentage of positive sentinel ILI/ARI specimens had been decreasing, this week it remained at a similar level to the previous week.
    • 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 the former remaining predominant in most northern European countries and the latter in eastern European countries and Ireland, Germany, Luxembourg and Spain.
    • In contrast to this time last season, very few influenza B detections have been reported.

    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 11/2014, the total number of specimens testing positive for influenza continued to decrease, with the positivity rate remaining stable compared to week 10: 13 561 specimens from sentinel and non-sentinel sources were tested for influenza, 2784 (20.5%) of which were positive: 2602 (93%) influenza A and 182 (7%) influenza B (Fig. 1 and 2).
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    Influenza A has remained the dominant virus type in circulation across the Region since week 40/2013.

    Of the 1505 influenza A viruses that were subtyped during week 11/2014, 722 (48%) were A(H1N1)pdm09 and 783 (52%) A(H3N2) (Fig. 2a).

    Influenza B accounted for a small proportion of influenza detections and has remained steady over the past weeks.

    Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 33 044 influenza detections: 31 556 (95%) were influenza A and 1488 (5%) influenza B viruses (Fig. 2b).

    Of the 21 566 influenza A viruses that have been subtyped, 12 216 (57%) were A(H1N1)pdm09 and 9350 (43%) were A(H3N2).

    In addition, since week 40/2013, the lineage of 129 influenza B viruses has been determined: 118 (91%) belonged to the B/Yamagata lineage (the lineage of the B virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 11 (9%) to the B/Victoria lineage.
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    (…)

    Similarly to the previous week, 27 countries reported influenza A as the dominant type in week 11/2014. Turkey reported influenza B as dominant, although it had few detections (Map 1 and country table).

    In countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in 12 countries (Croatia, Georgia, Germany, Ireland, Lithuania, Luxembourg, the Republic of Moldova, Romania, the Russian Federation, Slovenia, Spain and Ukraine), while 6 countries (Bosnia and Herzegovina, Denmark, Hungary, Norway, Sweden and the United Kingdom (Scotland)) reported A(H1N1)pdm09 as dominant.

    5 countries (Belgium, France, Italy, Latvia and Switzerland) 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, 1227 influenza viruses characterized antigenically by 13 countries (the Czech Republic, Denmark, Finland, Germany, 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 703 influenza viruses genetically (Fig. 4).
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    # 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, 8 countries (Greece, the Netherlands, Norway, Portugal, Spain, Sweden, the Russian Federation and the United Kingdom (England)) have screened 885 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

    Of the 671 A(H1N1)pdm09 viruses tested, 663 showed susceptibility to both drugs; 8 viruses carrying the neuraminidase H275Y amino acid substitution, causing resistance to oseltamivir, were detected in the United Kingdom in hospitalized patients, most of whom were treated with neuraminidase inhibitors.

    Of the 179 influenza A(H3N2) viruses tested, 178 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 35 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 107 influenza A(H1N1)pdm09 and 75 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 11/2014, most European countries continued to report low-intensity influenza activity (Map 2), with very few reporting increasing trends (Map 4). Regarding geographic spread, influenza activity varied between widespread, regional or sporadic among countries (Map 3).

    During week 11/2014, consultation rates stabilized in most countries in the Region. Of the 22 countries with established national thresholds, the rates remained above or at threshold levels in most countries. At the same time, more countries reported decreasing consultation rates than in previous weeks, mostly in the southern part of the Region. 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.

    (…)

    For the last 4 consecutive weeks, the percentage of positive sentinel ILI/ARI specimens has decreased, probably indicating that the influenza season has peaked. The percentage of positive sentinel ILI/ARI specimens was similar to that in the previous week (Fig. 5).
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    During week 11/2014, 403 (33%) of the 1225 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A(H3N2) (Fig. 6a) similar to the previous weeks. The number of influenza B detections remained low. Click here for a detailed overview in a table format.
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    Hospital surveillance for SARI

    For sentinel surveillance of severe disease due to influenza, in week 11/2014 most SARI cases were reported in those aged 0–4 years. A decreasing percentage of SARI patients tested positive for influenza for the second week in a row (Fig. 7).
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    During week 11/2014, 61 (26%) of the 234 SARI samples collected in Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, the Republic of Moldova, Romania, the Russian Federation, Serbia, Slovakia 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.
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    For week 11/2014, 6 countries (France, Ireland, Romania, Spain, Sweden and the United Kingdom) reported 152 hospitalized, laboratory-confirmed influenza cases, including 71 cases admitted to intensive care units (ICUs).

    Since week 40/2013, 7 countries have reported 3945 hospitalized, laboratory-confirmed influenza cases: 3904 (99%) were associated with influenza virus type A infection and 41 (1%) with type B virus.
    A total of 2654 influenza A viruses has been subtyped; 1982 (75%) were A(H1N1)pdm09 and 672 (25%) A(H3N2).

    5 countries reported a total of 324 fatal cases: 321 (99%) were associated with influenza virus type A infection and 3 (1%) with type B virus. Of 247 influenza A viruses subtyped in fatal cases, 200 (81%) were A(H1N1)pdm09 and 47 (19%) 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 11/2014 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
      • 27 samples were tested for influenza viruses: 17 were positive for RNA A(H3N2); 1 sample - RNA hRSV;

    • Romania
      • We report in TESSy only data from sentinel SARI Surveillance, but we also monitor the confirmed SARI cases, including deaths, detected by routine surveillance.
      • Including Week 11, we have a total number of 55 confirmed SARI cases, 26 with A(H1)pdm09, 28 with A(H3) and 1 with coinfection A(H1)pdm09&A(H3).
      • The total number of death is 15, 12 confirmed with influenza virus A(H1)pdm09 and 3 with A(H3).
      • Nine out of din 12 cases who died with A(H1)pdm09 are females, the median age is 53 years and the average is 51.
      • Ten out of 12 cases who died with A(H1)pdm09 had underlying risk conditions, but none of them had been previously vaccinated against influenza.
      • We have 2 cases confirmed with A(H3)previously vaccinated, one of whom died.
      • In the same period of the previous season, the number of registered deaths confirmed with influenza was 14, 11 with influenza A(H1)pdm09 and 3 with influenza B.

    (…)


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