The weekly/bi-weekly influenza surveillance overview is a collection of timely and relevant information regarding influenza activity in Europe. It provides key statistical data on a variety of issues including the following: sentinel surveillance of influenza like illness (ILI) and acute respiratory illness (ARI); virological surveillance; aggregate numbers of pandemic H1N1 2009; hospital surveillance of severe acute respiratory infection (SARI); mortality surveillance; and qualitative reporting. An up-to-date report is available on Fridays.