FDA Chooses Influenza Vaccine Strains for the 2018-19 Season

In March, the U.S. Food and Drug Administration’s (FDA) Vaccines and Related Biological Products Advisory Committee chosethe Northern Hemisphere’s 2018-19 influenza (flu) vaccine strains based on the World Health Organization’s recommendations. For the trivalent vaccine, the committee voted unanimously to include an A/Michigan/45/2015 (H1N1) pdm09-like virus and an A/Singapore/ INFIMH-16-0019/2016 (H3N2)-like virus, the latter of which is a change from the 2017-18 vaccine. And, the committee voted 11-1 to include a B/Colorado/ 06/2017-like virus (B/Victoria/2/87 lineage), which is also a change from the 2017-18 vaccine. The committee also voted unanimously to include a B/Phuket/ 3073/2013-like virus (B/Yamagata/16/88 lineage) as the second influenza B strain in the quadrivalent vaccine.

For the 2017-18 season, interim results show the vaccine lowered the number of cases of medically attended flu illness by 36 percent. Vaccine effectiveness against influenza A(H3N2) was 25 percent for all ages and 51 percent for children aged 6 months to 8 years. The vaccine was 67 percent effective against A(H1N1)pdm09, and 42 percent effective against influenza B (mostly B/Yamagata, not in inactivated influenza vaccine, trivalent).

“In terms of last year’s vaccine … even though we’ve had a bad flu year, the strains that were selected … were really good selections,” said Jack Bennink, PhD, a temporary voting member on the committee and senior managing epidemiologist at the National Institute of Allergy and Infectious Diseases. “They were as good as one could guess and make at the time. I don’t think we could’ve done any better, and I’m encouraged by the fact that particularly [in children aged 6 months] to 8 years old, it’s almost 60 percent effective.”