h1n1 swine origin influenza infection in the united states and europe in 2009 may be similar to h1n1 seasonal influenza infection in two australian states in 2007 and 2008. | the population-based impact of infection with swine origin influenza a (h1n1) virus infection was not clear in the early days of the epidemic towards the end of may 2009. australia had seven confirmed cases by 22 may 2009. we aimed to compare available data on swine origin influenza a (h1n1) virus infection overseas with seasonal influenza a (h1n1) virus infection in australia to assist with forward planning. | 2009 | 19627376 |