The World Health Organization (WHO) has recommended vaccine viruses for next year’s flu season, and the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC) has made the vaccine composition recommendation to be used in the U.S., according to the CDC.
Both agencies recommend that trivalent vaccines next season contain an A/Michigan/45/2015 (H1N1) pdm09–like virus, an A/Hong Kong/4801/2014 (H3N2)–like virus, and a B/Brisbane/60/2008–like (B/Victoria lineage) virus. For quadrivalent vaccines, which have two influenza B viruses, the makeup should include the viruses in the trivalent vaccines, as well as a B/Phuket/3073/2013–like (B/Yamagata lineage) virus, the recommendation states.
“This represents a change in the influenza A (H1N1) component compared with the composition of the 2016-2017 influenza vaccine,” the CDC explains. “The vaccine viruses recommended for inclusion in the 2017-2018 Northern Hemisphere influenza vaccines are the same vaccine viruses that were chosen for inclusion in 2017 Southern Hemisphere seasonal flu vaccines. These vaccine recommendations were based on several factors, including global influenza virologic and epidemiologic surveillance, genetic characterization, antigenic characterization, antiviral resistance, and the candidate vaccine viruses that are available for production.”
So far in the flu season, overall vaccine effectiveness (VE) against influenza A and influenza B virus infection associated with medically attended ARI was 48%, and most influenza infections were caused by A (H3N2) viruses, the CDC reports. VE was estimated to be 43% against illness caused by influenza A (H3N2) virus and 73% against influenza B virus. The report uses data from 3,144 children and adults enrolled in the U.S. Influenza Vaccine Effectiveness Network from November 28, 2016 to February 4, 2017.
The latest news may be about next year’s flu season, but this year’s outbreak remained widespread in 36 states as of mid-March.
So far, 13,133 laboratory-confirmed influenza-associated hospitalizations have been reported for an overall hospitalization rate of 46.9 per 100,000 population. Most, 89.8%, were associated with influenza A virus, 9.6% with influenza B virus, 0.3% with influenza A virus and influenza B virus co-infection, and 0.3% with influenza virus for which the type was not determined. Among those with influenza A subtype information, 98.0% were A(H3N2) and 2.0% were A(H1N1)pdm09 virus.