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EuroFlu - Weekly Electronic Bulletin - Week 9 : 24/02/2014-02/03/2014 - 07 March 2014, Issue No. 520 (edited)

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  • EuroFlu - Weekly Electronic Bulletin - Week 9 : 24/02/2014-02/03/2014 - 07 March 2014, Issue No. 520 (edited)

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


    EuroFlu - Weekly Electronic Bulletin - Week 9 : 24/02/2014-02/03/2014 - 07 March 2014, Issue No. 520

    Influenza activity declining in south-western Europe


    Summary, week 09/2014
    • During week 09/2014 consultation rates for influenza-like illness (ILI) and/or acute respiratory infection (ARI) continued to decline in most southern and western countries in the WHO European Region, with fewer countries in the rest of the Region reporting increasing activity than in the previous week.
    • In a number of north-western countries (the Czech Republic, Denmark, Germany Latvia, Lithuania Luxembourg, the Netherlands, Norway, Slovakia, Switzerland and the United Kingdom (England)) consultation rates have been very low since the beginning of the season (mostly below threshold) and much lower than last season.
    • The percentage of sentinel influenza detections decreased in some southern countries, but increased in others.
    • 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 A(H1N1)pdm09 remaining predominant in most northern European countries while A(H3N2) predominated in eastern European countries and Ireland, Germany and Luxembourg.
    • There have been very few reports of influenza B this season; about 40% of virus detections were influenza B at the same time last year.

    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 09/2014, 14 459 specimens from sentinel and non-sentinel sources were tested for influenza, 3161 (22%) of which were positive: 3018 (95%) influenza A and 143 (5%) influenza B (Fig. 1 and 2).
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    Influenza A has remained the dominant virus type across the Region since week 40/2013.

    Of the 1869 influenza A viruses that were subtyped during week 09/2014, 1102 (59%) were A(H1N1)pdm09 and 767 (41%) A(H3N2) – similar to the ratio in the previous week (Fig. 2a).

    Since the beginning of weekly monitoring (week 40/2013), sentinel and non-sentinel sources have yielded 27 488 influenza detections: 26 365 (96%) were influenza A and 1123 (4%) influenza B viruses (Fig. 2b).

    Of the 18 800 influenza A viruses that have been subtyped, 11 558 (61%) were A(H1N1)pdm09 and 7242 (39%) were A(H3N2).

    In addition, since week 40/2013, the lineage of 110 influenza B viruses has been determined: 100 (91%) belonged to the B/Yamagata lineage (the lineage of the B virus recommended by WHO for inclusion in trivalent seasonal influenza vaccines) and 10 (9%) to the B/Victoria lineage.
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    (…)

    Similarly to the previous week, 30 countries reported influenza A as the dominant type in week 09/2014.

    Turkey reported influenza B as dominant, despite having a low level of detections (Map 1 and country table).

    In countries providing data on dominant subtypes, influenza A(H3N2) was reported as dominant in 9 countries (Georgia, Germany, Ireland, Luxembourg, the Republic of Moldova, Romania, Slovenia, the former Yugoslav Republic of Macedonia and Ukraine), while 11 countries (Bulgaria, Denmark, Estonia, Finland, Greece, Hungary, Iceland, Norway, Spain, Sweden and the United Kingdom (Scotland and Wales)) reported A(H1N1)pdm09 as dominant. 8 countries (Albania, Belgium, France, Italy, Kazakhstan, Latvia, the Russian Federation 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, 853 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).

    15 countries (Belgium, the Czech Republic, Denmark, Finland, Germany, Greece, Ireland, the Netherlands, Norway, Portugal, the Russian Federation, Spain, Sweden, Switzerland and the United Kingdom (Scotland)) have characterized 574 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 728 viruses for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir.

    Of the 587 A(H1N1)pdm09 viruses tested, 582 showed susceptibility to both drugs.

    5 viruses carrying the neuraminidase H275Y amino acid substitution, causing resistance to oseltamivir, were detected in the United Kingdom in hospitalized patients treated with oseltamivir.

    Of the 112 influenza A(H3N2) viruses tested, 111 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 29 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 96 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 09/2014, most European countries continued to report low-intensity influenza activity (Map 2), with fewer countries reporting increasing trends than in previous weeks (Map 4). Regarding geographic spread, influenza activity remained predominantly regional or widespread all over the Region (Map 3).

    During week 09/2014, consultation rates stabilized in most countries in the Region. Of the 22 countries with established national thresholds, the consultation rates remained above or at threshold levels inmost. At the same time, more countries reported decreasing consultation rates than in previous weeks, mostly in the southern part of the Region (Bulgaria, Italy, Portugal, the Republic of Moldova and Spain), where the influenza season started earlier than elsewhere in the Region.

    (…)

    During week 09/2014, the percentage of positive sentinel ILI/ARI specimens decreased slightly from previous weeks, and remained lower than in the same week of the four preceding seasons (Fig. 5).
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    During week 09/2014, 575 (34%) of the 1717 specimens collected from sentinel sources tested positive for influenza, the majority being influenza A(H3N2) similar to the previous week (Fig. 6a). Click here for a detailed overview in a table format.
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    Hospital surveillance for SARI

    For surveillance of severe disease due to influenza, the number of SARI hospitalizations associated with influenza infection decreased slightly in comparison with the previous week. Most SARI cases were reported in those aged 0–4 years, and a decreasing percentage of SARI patients tested positive for influenza (Fig. 7).

    For several weeks, coinciding with increased positivity rates, 3 countries (Georgia, Serbia and Romania) showed increases in cases in the groups aged 30–64 and/or ≥65 years, while increases in cases in the group aged 15–29 were observed in Albania, Armenia and the Russian Federation.
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    During week 09/2014, 88 (30%) of the 298 SARI samples collected in Albania, Armenia, Belarus, Georgia, Kazakhstan, the Republic of Moldova, Romania, the Russian Federation, Serbia and Ukraine tested positive for influenza A, the majority being A(H3N2), in line with the results of outpatient surveillance (Fig. 8a). Click here for a detailed overview in table format.
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    For week 09/2014, 7 countries (Finland, France, Ireland, Romania, Spain, Sweden and the United Kingdom) reported 217 hospitalized, laboratory-confirmed influenza cases, including 100 cases admitted to intensive care units (ICUs).

    Since week 40/2013, 7 countries have reported 3400 hospitalized, laboratory-confirmed influenza cases: 3367 (99%) were associated with influenza virus type A infection and 33 (1%) with type B virus.

    A total of 2275 influenza A viruses have been subtyped, 1758 (77%) were A(H1)pdm09 and 517 (23%) were A(H3N2), which is in general inline with the results of outpatient surveillance in these countries.

    7 countries reported a total of 284 fatal cases: 282 (99%) were associated with influenza virus type A infection and 2 (1%) with type B virus. Of 218 influenza A viruses subtyped in fatal cases, 182 (83%) were A(H1)pdm09 and 36 (17%) as A(H3).

    SARI 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.

    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 09/2014 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 09 were tested 30 samples for influenza viruses: 15 were positive for RNA A(H3N2); 1 sample - RNA hRSV; 1 sample - DNA Adenovirus, and 1 sample was positive for RNA hRSV+ RNA hPiv1.

    (…)


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