The progression of the pandemic in Victoria is shown in Figure 1 . The original research plan was to obtain 2 serum samples, 3 months apart, from all participants to test for seroconversion and also to obtain weekly nose swabs for pandemic infl uenza detection by using real-time PCR. By the time the study commenced, the pandemic was waning, infl uenza cases were decreasing in Victoria, and following the original study plan was not considered feasible.