Weekly influenza surveillance overview, February 11, 2011 - Week 5

Most European countries continue to report medium to high influenza-like illness/acute respiratory infection consultation rates and widespread activity. Increasing trends are mainly observed in central, eastern and southern Europe whereas countries in western and northern Europe are reporting unchanging or declining trends.The proportion of influenza-positive sentinel specimens is gradually decreasing, having now reached 46%.67% of influenza virus detections in week 5/2011 were type A, 33% were type B. In nine countries, type B detections exceeded those of type A. More than 98% of subtyped influenza A viruses were A(H1N1)2009.In week 5/2011, ten countries reported 194 all-cause SARI and confirmed hospitalised influenza cases, the latter mostly due to influenza A(H1N1)2009.Numbers of influenza infections with severe outcome have declined in western European countries (Denmark, France, the Netherlands, Ireland and the UK). However, there is now considerable uncertainty on information concerning severe cases in central and eastern European countries.