Weekly influenza surveillance overview, February 18, 2011 - Week 6

Surveillance report

Most European countries continue to report medium to high influenza-like illness /acute respiratory infection consultation rates and widespread activity. Decreasing ILI/ARI trends were reported by 14 countries.The proportion of influenza virus-positive sentinel specimens has gradually decreased to 43%after peaking in week 52/2010 at 57%Sixty-seven per cent of influenza virus detections in week 6/2011 were type A, 33% were type B. More than 99% of subtyped influenza A viruses were A(H1N1)2009.In week 6/2011, ten countries reported 180 all-cause SARI and hospitalised confirmed influenza cases, the latter mostly due to influenza virus A(H1N1)2009 infection.Numbers of influenza infections with severe outcome have decreased in western European Union countries (Denmark, France, the Netherlands, Ireland, Spain and the UK). However, there is considerable uncertainty about severe cases in a number of countries, especially those in central, eastern and south-eastern European countries, because of limited hospital surveillance.