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Start of the seasonal influenza epidemics 2010-11? EU/EEA countries (ECDC, Dec. 22 2010, extract, edited)

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  • Start of the seasonal influenza epidemics 2010-11? EU/EEA countries (ECDC, Dec. 22 2010, extract, edited)

    Start of the seasonal influenza epidemics 2010-11? EU/EEA countries (ECDC, Dec. 22 2010, extract, edited)


    [Source: European Centre for Disease Prevention and Control (ECDC), full PDF document (LINK). Extract, edited.]

    ECDC HEALTH INFORMATION

    Start of the seasonal influenza epidemics 2010-11? EU/EEA countries

    22 December 2010


    The purpose of this document is to provide some information to health professionals on the start of the seasonal influenza season 2010-11 across the EU/EEA countries.


    Key facts

    The following facts have been published in the Weekly Influenza Surveillance Overview (WISO) ? for Week 49:
    • Rates of community consultation for influenza-like illness are rising in 14 out of 29 EU/EFTA countries;
    • So far, the isolates are predominantly influenza A(H1N1)2009 and influenza B viruses ? with only a few A(H3N2) viruses ? so it is reasonable to expect qualitative differences compared with the ?old? pre-2009 seasonal influenza;
    • There is little difference from the strains contained in this year's seasonal influenza vaccine;
    • There is little evidence of any antiviral resistance to either oseltamivir or zanamivir;
    • The earliest affected country so far is the United Kingdom; therefore that country?s experience and response is instructive (UK Health Protection Agency Seasonal influenza website);
    • Respiratory syncytial viruses are also circulating at present.


    Background

    In the EU/EEA countries, influenza epidemics usually progress from west to east(1). The character of influenza epidemics can change in the course of a season. However, EU/EEA countries usually have similar experiences of seasonal influenza within any one season unless new strains emerge in the same season (e.g. in 2007-8)(2)

    This 2010-11 season may differ from the usual pattern, due to highly variable use of pandemic vaccines in 2009 with high coverage in some Nordic countries(3).

    This initial picture in the EU is consistent with the experience in some temperate countries in the southern hemisphere (e.g. New Zealand) in their 2010 winter (May to September)(4).

    As in some other influenza seasons, what the EU/EAA countries are experiencing is different from North America and Asia (so far dominated by influenza A(H3N2)(5). But it is important to note that influenza can always surprise.


    The experience in the United Kingdom: useful for other countries

    The experience in the United Kingdom can give some important indications of what is most likely to occur soon in other EU/EEA countries, except those that had a high coverage with the pandemic vaccine in 2009 (such as Finland, Norway and Sweden).

    According to the information provided by the Health Protection Agency (week 49 report)
    • there has been considerable pressure on intensive care units and extra corporeal membrane oxygenation (ECMO) since early December 2010;
    • community consultation rates crossed the epidemic threshold in weeks 48 and 49, but influenza rates in the community have been lower than would be expected from the observed pressure on intensive care units. This may reflect the fact that, similar to the situation during the pandemic but in contrast to previous seasonal influenzas, most people infected with the influenza A(H1N1)2009 virus experience only mild illness or no illness at all, but in a few the infection results in a very severe disease(6)
    • The pattern of severe disease is similar to the that observed during the pandemic:
      • most patients affected are under 65 years-old;
      • most, but not all have risk factors (chronic disease or pregnancy);
      • as of 16 December, 17 deaths have been reported including one pregnant woman;
      • of the 14 fatal cases for whom vaccination records were available, none had had the 2009 pandemic vaccine or the 2010 seasonal vaccine, which is compatible with the fact that the vaccine is up to 80% effective;
    • virological analysis of isolates from this season's severely affected cases has not revealed any observable difference to the influenza A(H1N1) viruses since 2009; it is therefore likely that the higher impact on hospitals simply reflects the effect of influenza B viruses present in addition to the A(H1N1) viruses;
    • It is important to monitor the virology carefully and relate them to the clinical details, because an unexplained oseltamivir resistance has been noted in a very few cases.


    Actions adopted in the United Kingdom

    Actions recently adopted in the United Kingdom include:
    • Preparing intensive care and ECMO services to accommodate more pressure;
    • Emphasising seasonal immunisation especially for risk groups, i.e. pregnant women and those with chronic medical conditions(7)
    • Advocating use of antivirals for people with possible influenza who are ill enough to be hospitalised and for ill patients seen in primary care, those who belong to a risk group and also others that doctors consider would benefit(8).

    (...)


    (1) Paget J, Marquet R, Meijer A, van der Velden. Influenza activity in Europe during eight seasons (1999-2007): BMC Infect Dis. 2007;7(1):141. (LINK)
    (2) Meijer A, Lackenby A, Hungnes O, et al. Oseltamivir-resistant influenza A (H1N1) virus, Europe, 2007?08 season. Emerg Infect Dis. 2009;15(4):552-60. (LINK)
    (3) Merecekiene J on behalf of the VENICE Consortium. Overview of pandemic A(H1N1) 2009 influenza vaccination in Europe. Preliminary results of survey conducted by VENICE, 2010 ESCAIDE Conference; Lisbon; 13 November 2010. (LINK)
    (4) Likely scenarios and uncertainties in the 2010/2011 influenza season in Europe and beyond. ECDC Forward Look Risk Assessment. October 2010. (LINK)
    (5) World Health Organisation Influenza Update No 123. Geneva: WHO; 17 December 2010. (LINK)
    (6) Miller E, Hoschler K, Hardelid P, Stanford E, Andrews N, Zambon M. Incidence of 2009 pandemic influenza A H1N1 infection in England: a cross-sectional serological study. Lancet, ;375(9720):1100-8. doi:10.1016/S0140-6736(09)62126-7 (LINK)
    (7) Flu vaccination for pregnant women. UK Department of Health; 16 December 2010. (LINK)
    (8) Treatment guidelines for patients with influenza 2010/2011. UK Department of Health; 14 December 2010. (LINK)

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