EU/EEA Countries) January 2011
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ECDC RISK ASSESSMENT Seasonal influenza 2010–2011 in Europe (EU/EEA countries) January 2011 Contents Contents ............................................................................................................................................................... 1 Executive summary ................................................................................................................................................ 2 Source, and type of request .................................................................................................................................... 3 Questions .............................................................................................................................................................. 3 Consulted experts .................................................................................................................................................. 3 Evidence accessed ................................................................................................................................................. 3 Risk assessment..................................................................................................................................................... 4 Epidemiological situation and impact on the health services .................................................................................... 4 Virological situation in the EU/EEA ........................................................................................................................ 6 Maps of intensity and spread, EU/EEA countries .................................................................................................... 7 International Virological Picture ............................................................................................................................ 9 Likely immunity to circulating viruses: natural and acquired immunity – serosurveys ................................................. 9 Vaccine coverage ................................................................................................................................................ 9 Impact on health services .................................................................................................................................. 11 The southern hemisphere experience ................................................................................................................. 11 Likely effectiveness of countermeasures including vaccination and antivirals .......................................................... 11 Safety of interventions ...................................................................................................................................... 12 ECDC scientific and public health advice .............................................................................................................. 12 Interpretation of the current situation, specific questions, and remaining uncertainties ........................................... 13 What can be anticipated for the rest of the season (20 January 2011) ................................................................... 13 Other uncertainties ........................................................................................................................................... 14 Date for next update ......................................................................................................................................... 14 References .......................................................................................................................................................... 15 Stockholm, January 2011 The Risk assessment was corrected on 6 May 2011: Page 4 ‘Risk assessment’ paragraph 3. Spain added to the sentence ‘notably France, the Netherlands, Norway and Spain.’ © European Centre for Disease Prevention and Control, 2011. Reproduction is authorised, provided the source is acknowledged. EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL Influenza risk assessment Executive summary The 2010/11 seasonal influenza epidemics in Europe are dominated so far by the A(H1N1)2009 viruses which emerged in the 2009 pandemic, although these are now considered seasonal viruses. There are also some B viruses circulating. Both are causing some severe disease and premature deaths but the preliminary data indicate that 90% of the fatalities are due to A(H1N1)2009 This is the first European influenza season after the 2009 pandemic. Many of the features and required countermeasures are the same as for the previous seasonal influenzas (which ran until the 2008/09 season). However, there are important differences which Europe needs to take into consideration, notably the type of people who are most affected and experiencing severe disease. In the first affected country (the United Kingdom) there have been higher numbers of people seeking care than on average with seasonal influenza. Also, the number of people with severe disease has been considerably higher than during the pandemic with at its peak 1.4 persons/105 population requiring higher level (intensive) hospital care at one time. The reason for the latter finding is unclear. Part of the reason for the increased demand in primary care has been persons seeking immunisation or treatment as information on the severe cases became apparent to the public. These phenomena have also been observed in other countries in Western Europe, albeit at lower levels. A broad pattern of west to east progression of influenza epidemics is underway, such as has been seen in previous years. Hence the experience of the Western countries can inform those further to the east of the European Union. All these considerations constitute the justification for this Interim ECDC Risk Assessment, which will be updated at intervals. Those mostly reported as experiencing severe disease or dying prematurely are those adults below the age of 65 years and children in the clinical risk groups. These constitute over 80% of cases reported. Severe disease also affects some pregnant women. There are also some previously entirely healthy people, who account for 20% of the deaths in the UK, and higher percentages requiring higher-level (intensive) hospital care in France. As in the pandemic, there have been some older people experiencing severe disease but reported cases have been low in numbers. Numbers of severely ill cases requiring care are now declining in the UK but they are rising in other countries. It cannot be anticipated whether those countries will experience the same rates as the UK. The circulating viruses have not as yet changed or mutated, and it is expected that the seasonal vaccines will be effective in preventing disease. ECDC-coordinated studies in the pandemic found up to 80% effectiveness for vaccines containing A(H1N1)2009. Other observational studies have confirmed this. Indeed there are encouraging data suggesting that significant protection develops within a week of immunisation. Data on the early deaths in the UK indicate that the vaccines in use are also effective in preventing influenza-related deaths. Recent surveys of pandemic and seasonal vaccine coverage by Member States indicate that there are many people in the clinical risk groups in Europe who remain unvaccinated, either with the pandemic vaccine or the 2010 seasonal vaccine. In the UK, there is a rise in laboratory reports of two or more severe invasive bacterial diseases; pneumococcal disease and group A streptococcal disease has been observed. Rates of invasive streptococcal disease rose to 0.33/105 population in December 2010 compared to 0.19/105 in an average year. To date, this has not been reported elsewhere in Europe. It is unclear whether this rise is associated with the influenza epidemics and contributing to the high numbers of severe cases in the UK, but that is a possibility. The scientific evidence to date provides justification for the following countermeasures already adopted by some countries in addition to the usual influenza personal protective measures (early self isolation, respiratory hygiene and hand-washing): • Continued vaccination of all those recommended for vaccination following national guidelines but especially clinical risk groups, including pregnant women, especially as it seems that the vaccine provides some protection even just a week after injection. However, there may be vaccine availability, logistical and administrative issues that will make this difficult in some settings. • Use of antiviral treatment in those presenting with severe influenza-like illness, pending virological confirmation, and in those with risk factors with milder disease. • Alerting higher level healthcare services of potential increased numbers of influenza patients this winter, potentially already in the next few weeks. • Advising clinicians to be vigilant to the possibility of severe illness due to bacterial co-infection with influenza, including invasive group A streptococcal, pneumococcal and meningococcal infection, and to be aware of the possibility of such bacterial co-infection in people with flu-like illness. • Use or creation of clinical networks for surveillance, evaluation and sharing of clinical experience. This is an interim risk assessment and will be up-dated at intervals as more data and analyses emerge. 2 EUROPEAN CENTRE FOR DISEASE PREVENTION AND CONTROL Influenza risk assessment Source, and type of request ECDC internal decision: urgent;