People in Australia and New Zealand (ANZ) were significantly affected by the virus, with a total of 43,700 confirmed cases in Australia as of October 2010, with 6,064 cases occurring between 1 January and 15 October 2010 [2] . We have reported previously the serious impact of the virus on the provision of critical care services in 2009 [3] . In order to rapidly inform health professionals in the Northern Hemisphere this study censored new incident cases before the end of the influenza season. In 2010, the deployment of vaccination and the acquisition of natural immunity against H1N1 2009 were expected to decrease the burden of disease due to influenza [4] . Australia and New Zealand were among the first countries to experience a second influenza season with H1N1 2009 following widespread deployment of vaccination.