BETHESDA, MD 28 February 2013—Advisers to FDA on Wednesday recommended that two components of the currently licensed trivalent influenza virus vaccines be replaced for the 2014–15 influenza season.
The advisers' recommendations match those made last week by the World Health Organization (WHO) for Northern Hemisphere influenza vaccines for the 2013–14 flu season.
"I think you have to realize what the impact on the global community is if we disagree" with WHO, said meeting chairman and pediatric infectious disease specialist Robert Daum of the University of Chicago.
In brief, the recommendations are to retain the influenza type A H1N1 component from this season's trivalent vaccines—known officially as an A/California/7/2009-like virus—and replace the A H3N2 and type B portions of the vaccines.
The recommended H3N2 component for the upcoming flu season is an A/Victoria/361/2011-like virus, and the recommended type B component is a Yamagata-lineage B/Massachusetts/2/2012-like virus.
For quadrivalent vaccines, which contain a second type B component, the recommendation for that portion is unchanged from last season: a Victoria-lineage B/Brisbane/60/2008-like virus. Two quadrivalent flu vaccines are currently approved for use in the United States.
The call for a new H3N2 component was made not because circulating viruses no longer match the vaccine strain but because the egg-adapted source virus for vaccine production has changed antigenically compared to cell-grown source virus.
The current flu season is the first during which cell-culture-derived influenza virus vaccine was available in the United States. All but 1 of the 10 nonrecombinant U.S.-licensed seasonal influenza virus vaccines are made from virus propagated in chicken eggs.
The recommendation to change the type B strain was made to better protect against viruses that emerged during the current flu season.
FDA's Vaccine and Related Biological Products Advisory Committee meets each winter to discuss the composition of the upcoming flu season's vaccines.