March 25, 2015
Hoping for a Better Match: Components of New Flu Vaccine Announced

Atlanta—This influenza season, the CDC and international health organizations were caught unawares when more than two-thirds of circulating H3N2 viruses drifted from the strain that was recommended for vaccine production.

Hoping for a better match, the World Health Organization now has recommended vaccine viruses for the 2015-2016 Northern Hemisphere vaccines, and the FDA’s Vaccines and Related Biological Products Advisory Committee has made recommendations for the composition of the 2015-2016 influenza vaccines to be used in the United States.

Both agencies recommend that trivalent vaccines contain an A/California/7/2009-like ((H1N1)pdm09) virus, an A/Switzerland/9715293/2013-like (H3N2) virus, and a B/Phuket/3073/2013-like (B/Yamagata lineage) virus.

Quadrivalent vaccines, which have two influenza B viruses, are recommended to contain those viruses as well as a B/Brisbane/60/2008-like (B/Victoria lineage) virus.

That means that the influenza A (H3) and influenza B (Yamagata lineage) components have changed from the current vaccine. The CDC notes that the vaccine recommendations were based on several factors, including global influenza virologic and epidemiologic surveillance, genetic characterization, antigenic characterization, antiviral resistance, influenza vaccine effectiveness, and the availability of potential vaccine virus candidates.

In February, updated interim influenza vaccine effectiveness (VE) estimates for the current 2014-2015 season were presented by the VDC to the Advisory Committee on Immunization Practices. The updated VE estimate against influenza A H3N2 viruses was 18%, similar to the earlier 23% estimate preliminarily reported in January.

Meanwhile, The VE estimate against influenza B viruses this season was 45%.

“When VE against all influenza viruses was combined, the overall VE estimate was 19% (95% CI: 7%-29%). In practical terms, this means the flu vaccine reduced a person’s risk of having to seek medical care at a doctor’s office for flu illness by 19%,” the CDC reported.

U.S. Pharmacist Social Connect