The trivalent influenza vaccine for the 2013-2014 season in the United States should retain one of the two influenza A strains included in the current vaccine, but the second influenza A strain and the influenza B strain should be replaced, a Food and Drug Administration expert panel agreed on Feb. 27.
At a meeting of the FDA’s Vaccines and Related Biological Products Advisory Committee, members voted 17-0 that next season’s influenza vaccine should retain the current influenza A (H1N1) strain, an A/California/7/2009 (H1N1)-like virus. They also voted 16-0 with one abstention to replace the influenza A (H3N2) component with an A (H3N2) virus described as "antigenically like the cell-propagated prototype virus A/Victoria/361/2011."
For the influenza B component, the panel voted 17-0 to replace the current strain with another B/Yamagata lineage strain, a B/Massachusetts/2/2012-like virus.
And since quadrivalent influenza vaccines will be available for the first time for the coming season, the panel selected the B/Victoria lineage strain (a B/Brisbane/60/2008-like virus) included in recent vaccines as the second B strain. That vote was 16-0, with one abstention.
The FDA panel meets at the same time each year to review influenza surveillance and epidemiology data in North America and globally, antigenic characteristics of influenza virus strains currently circulating in human populations, and serologic responses to circulating influenza viruses of people immunized with the current approved vaccine.
The panel’s recommendations echo those of the World Health Organization, which were made earlier in February.
The coming flu season will be the first time a quadrivalent vaccine is available. MedImmune will supply only the quadrivalent form of FluMist for the 2013-2014 season, discontinuing the trivalent form, according to a representative.
GlaxoSmithKline will manufacture both the trivalent and quadrivalent forms of Fluarix for next season, a company representative said.
Dr. David Greenberg of Sanofi Pasteur said that the company expects its quadrivalent influenza vaccine, currently being reviewed by the FDA, to be licensed in the summer. The company plans to launch a limited supply for the next season, but most of the GSK 2013-2014 vaccine will be the trivalent version, he added.
The current influenza season started about 4 weeks earlier than usual in the United States with "moderately high" activity. Activity increased in late November and peaked in late December, according to Dr. Lynn Finelli of the influenza surveillance and outbreak response team at the Centers for Disease Control and Prevention.
At the meeting, Dr. Finelli said that influenza activity has dropped in most parts of the United States, with moderate activity continuing only in parts of the West. As of Feb. 16, a total of 78 influenza-associated pediatric deaths had been reported. In comparison, 34 pediatric deaths were reported in the 2011-2012 season, 122 during 2010-2011, and 282 in 2009-2010.
Dr. Finelli also presented data that indicate suboptimal vaccine effectiveness against A (H3N2) among adults aged 65 years and older – only about 9%, compared with 46%-58% for younger age groups.
Her presentation led to a discussion of why the influenza vaccine is less effective in the older population, including whether the high-dose version of Fluzone, licensed for people 65 years and older, was more effective. High-dose Fluzone was licensed as an accelerated approval, and a trial to confirm its clinical benefit in the indicated age group is underway.
Sanofi Pasteur’s Dr. Greenberg, who was in the audience, said that the results of the study, which compares high-dose Fluzone to Fluzone, are expected in 2014 or 2015.
The FDA usually follows the recommendations of its advisory panels. Panelists have been cleared of potential conflicts of interest related to the topic of the meeting. Occasionally, a panelist may be given a waiver, but not at this meeting.