Weekly influenza surveillance overview, 14 December 2012 - week 49

In week 49/2012, all 24 countries reporting experienced low-intensity levels of influenza-like illness or acute respiratory infection. For the first time this season, the majority of the countries reported sporadic geographic spread and eight countries experienced increasing trends. This is the second consecutive week with a notable increase in the proportion of influenza-positive samples since the start of the season. The number of respiratory syncytial virus (RSV) detections remained high and there was one report of a hospitalised laboratory-confirmed influenza case due to influenza B virus infection. The viruses circulating this season remain well-matched with the 2012/13 seasonal vaccine viruses. Based on reports of local or sporadic spread from the majority of countries and the increasing proportion of specimens testing positive for influenza virus, the season of influenza transmission appears to have started in EU/EEA countries.