Annual report of the National Influenza Surveillance Scheme, 2010

The 2010 influenza season was moderate overall, with more laboratory-confirmed cases than in earlier years (with the exception of 2009). That said, self-reported influenza-like illness (ILI) was equal to or lower than 2008 and earlier years. In 2010, the number of laboratory-confirmed notifications for influenza was 0.8 times the 5-year mean. High notification rates were reflected in an increase in presentations with ILI to sentinel general practices and emergency departments. Notification rates were highest in the 0-4 year age group. Infections during the season were predominantly due to influenza A(H1N1)pdm09, with 90% of notifications being influenza A (56% A(H1N)1pdm09, 30% A(unsubtyped) and 4% A(H3N2)) and 10% being influenza B. The A(H1), A(H3) and B influenza viruses circulating during the 2010 season were antigenically similar to the respective 2010 vaccine strains. Almost all (99%) of the circulating influenza B viruses that were analysed were from the B/Victoria lineage.