FDA Recommends Changes for 2006-2007 Flu Vaccine

The emergence of two new influenza strains has led the US Food and Drug Administration (www.fda.gov) to recommend changes for next season’s flu vaccine.

Each year's flu vaccine comprises three different strains, typically two "A" influenza strains and one "B" strain. One of the strains, the A/New Caledonia strain, will remain the same. The panel recommended replacing the current A/California strain to a Wisconsin strain and the current B influenza strain from a Shanghai virus to a Malaysia virus.

The World Health Organization made similar recommendations.

The panel also recommended the FDA convene a workshop to discuss the possibility of having the annual influenza vaccine include four flu strains rather than the current three. Panel members debated whether putting an additional B strain in each year's influenza vaccine could make it more protective, while some manufacturers argued that adding a fourth strain could cut overall vaccine manufacturing capacity by about 25% under the current egg-based manufacturing system. (Each year's flu strains are grown in chicken eggs before being placed into a vaccine, a process that takes months.)