Weekly Influenza Surveillance Overview, 15 April 2011 - Week 14

Twenty-four of the 25 reporting countries experienced low influenza activity, while Sweden reported medium activity. Stable or decreasing trends were reported by 25 countries. During week 14/2011, of 47 influenza viruses detected in sentinel specimens, 37 (78.7%) were influenza B viruses and 10 (21.3%) were influenza A viruses. For the fourth consecutive week, influenza B viruses were detected more frequently than influenza A viruses.