Recommended composition of influenza virus vaccines for use in the 2005 influenza season.

This recommendation relates to the composition of vaccines for the forthcoming winter in the southern hemisphere (May–October 2005). A recommendation will be made in February 2005 which relates to vaccines that will be used for the winter in the northern hemisphere (November 2005–April 2006). Epidemiological considerations will influence which recommendation (September 2004 or February 2005) is more appropriate for countries in equatorial regions.