Weekly influenza surveillance overview, March 25, 2011 - Week 11

In week 11/2011, 16 EU countries experienced influenza activity of low intensity and 22 countries reported stable or decreasing trends. Nevertheless, widespread activity was still reported by two countries.In week 11/2011, 46.1% of detected influenza viruses were of type A, and 53.9% were of type B. This latter virus was dominant in seven countries and co-dominant with influenza virus A(H1N1) 2009 in five countries. It was the first week of this season that the influenza B virus was overall dominant.Six countries notified 71 severe respiratory cases, of which 34 were infected by an influenza virus.