Epidemiological and virological assessment of influenza activity in Europe, during the 2006-2007 winter.

Influenza surveillance in Europe is based on influenza surveillance networks that cooperate and share information through the European Influenza Surveillance Scheme (EISS). EISS collected clinical and virological data on influenza in 33 countries during the 2006-2007 winter. Influenza activity started around 1 January and first occurred in Greece, Scotland and Spain. It then moved gradually across Europe from south to north and lasted until the end of March. In 29 out of 33 countries, the consultation rates for influenza-like-illness or acute respiratory infections in the winter of 2006-2007 were similar or somewhat higher than in the 2005-2006 winter. The highest consultation rates for influenzal ike-illness were generally observed among children aged 0-4 years and 5-14 years. The predominant virus strain was influenza A (97% of total detections) of the H3 subtype (93% of H-subtyped A viruses; 7% were A(H1)). The influenza A(H3) and A(H1) viruses were similar to the vaccine reference strains for the 2006-2007 season, A/Wisconsin/67/2005 (H3N2) and A/New Caledonia/20/99 (H1N1) respectively. The majority of the influenza B viruses were similar to the reference strain B/Malaysia/2506/2004, included in the 2006-2007 vaccine. In conclusion, the 2006-2007 influenza season in Europe was characterised by moderate clinical activity, a south to north spread pattern across Europe, and a dominance of influenza A(H3). Overall there was a good match between the vaccine virus strains and the reported virus strains.