This study will be conducted during the 2008-2009 influenza season in North America and Hong Kong, which is anticipated to run from November 2008 to May 2009. Should the influenza season conclude in North America and Hong Kong prior to the attainment of the minimum target enrollment specified in the FLU-05 study, study sites in Australia will also be enlisted in order to enroll subjects; in such a case, enrollment will continue during the 2009 influenza season in these countries, which is anticipated to run from May through October, 2009.