The UK Health Protection Agency (HPA) has observed an increase in people with severe influenza infections in England in the last two weeks. Many, but not all, of the reported cases have underlying conditions, including pregnancy. Most cases are associated with A(H1N1) 2009 infection and sporadic ones with flu B. None of the five fatal cases with information available had received the 2010/11 seasonal influenza, or the 2009 monovalent pandemic influenza vaccine. Given the effectiveness of the vaccine against A(H1N1)2009 observed in research undertaken during the pandemic in Europe greater coverage among risk groups would be expected to have prevented at least some of these severe cases [1],[2],[3],[4]
The evidence coming from the European Influenza Surveillance Network (EISN) and appearing in the most recent Weekly Influenza Surveillance Overview indicates that the 2010/2011 influenza season in the EU has started [3]. It is presently dominated by influenza A(H1N1) 2009, the virus strain that circulated during the 2009 pandemic, and influenza B viruses. This pattern is unsurprising. ECDC refreshed its Forward Look Risk Assessment in October 2010 drawing on the experience of Southern hemisphere temperate countries which had the first post pandemic winter (May to September 2010). It concluded that epidemic transmission of influenza was inevitable in the 2010/2011 winter but the intensity and viral mix could not be predicted. Transmission of A(H1N1) 2009 was considered most likely but equally on the basis of what happened in the South transmission of influenza B and A(H3N2) viruses was also possible.
Unless the characteristics of the current circulating viruses change, the compatibility with the new trivalent seasonal influenza vaccine should be adequate. Resistance to oseltamivir (or zanamivir) should be a less important issue as old oseltamivir resistant A(H1N1) virus has been displaced by the A(H1N1) 2009 virus.
ECDC is cooperating with the Member States, the Commission, the WHO, and EMA to monitor the situation and determine the optimal responses.
ECDC will continue to produce the Weekly influenza Surveillance Overview (WISO) and therefore monitor the main surveillance developments each week. The latest issue for week 48 (published December 10) reports increasing transmission in 10 countries (in addition to the UK) though none of the countries reports anything more than local spread. A new WISO will be published on December 17th. This relies on Member States continuing to report routinely through the European Influenza Surveillance Network.
ECDC would suggest all those Europeans who are offered the seasonal influenza vaccine to be vaccinated. It is of particular importance for those at higher risk for severe infections.
With the available information there is no reason to change existing guidance on preparedness and response plans for seasonal influenza. However, there is potential for countries to activate and strengthen existing plans for this season. Among the actions that have been adopted in the UK and some other countries there is e.g.
- alerting intensive health care services of potential increased numbers of influenza patients this winter; and
- increasing the awareness of clinicians.
Resources
- HPA Weekly National Influenza Report Summary of UK surveillance of influenza and other seasonal respiratory illnesses 9 December 2010 – Week 49
- HPA Press Release Antiviral drugs for seasonal flu approved as HPA urges at-risk groups to get vaccinated. 13 December 2010
- ECDC Executive Science Update No 11. April-June 2010 - Page 2 Effectiveness of seasonal and pandemic vaccines
- Wichmann O, Stöcker P, Poggensee G, Altmann D, Walter D, Hellenbrand W, Krause G, Eckmanns T. Pandemic influenza A(H1N1) 2009 breakthrough infections and estimates of vaccine effectiveness in Germany 2009-2010. Euro Surveill. 2010;15(18):pii=19561.
- WISO Week 48 December 10th 2010
Read more on ECDC site
Influenza;Influenza A(H1N1)v;Pandemic (H1N1) 2009;Seasonal Influenza;Influenza;