2 new influenza strains recommended for next season
REPORTING FROM AN FDA ADVISORY COMMITTEE MEETING
The advisory committee’s recommendation is identical to the recommendations recently made by the World Health Organization for next season’s influenza vaccines in the Northern Hemisphere. The WHO recommended that trivalent vaccines contain A/Michigan/45/2015 (H1N1)pdm09-like virus, A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus, and B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage). WHO also recommended that quadrivalent vaccines contain all of the above strains and B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage) as the second influenza B strain.
Most of the influenza activity in the United States this season is due to influenza A (H3N2) viruses (67%), according to Lisa Grohskopf, MD, associate chief for policy & liaison in the Influenza Division at the Centers for Disease Control and Prevention. Fortunately, the majority of circulating strains are similar to those contained in the 2017-2018 vaccine. Only strains with B/Victoria lineage displayed antigenic drift, but represented less than 1% of all circulating viruses.
Hospitalization rates for laboratory-confirmed influenza this season have been markedly higher among people aged 65 years and older, compared with younger age groups, and have increased since last season. As of Feb. 17, the preliminary estimate of hospitalizations in this age group was 322.7 cases per 100,000 people, compared with about 290.5 per 100,000 during the 2016-2017 season. There have been 97 pediatric deaths associated with influenza, compared with 110 reported during the 2016-2017 season, 93 during 2015-2016, and 148 during 2014-2015.
These data are not final because the flu season is still ongoing, but a full analysis will be provided at the end of the season, Dr. Grohskopf pointed out.With H3N2 strains of influenza A predominating, questions on the effectiveness of the newly recommended Singapore A(H3N2) were raised by the committee. Jacqueline Katz, PhD, director of the WHO Collaborating Center for Surveillance, Epidemiology, and Control of Influenza, reassured the committee.
