The FDA has given the nod to another influenza vaccine intended to protect against four strains of the virus, according to the drug's maker. The vaccine -- dubbed Fluarix Quadrivalent -- will be available for the 2013-2014 flu season, according to a release from GlaxoSmithKline (GSK), of London, England. Unlike current trivalent vaccines, it will include two strains of influenza B, as well as the standard two strains of influenza A.
The GSK drug is one of a number of quadrivalent vaccines under development; another is being produced by Sanofi Pasteur of Swiftwater, Pa., and has not yet been approved. The first such vaccine to be approved -- FluMist Quadrivalent, an attenuated live-virus vaccine made by Medimmune of Gaithersburg, Md. -- got the FDA OK Feb. 29. Two main lineages of influenza B -- dubbed Victoria and Yamagata -- have been circulating for more than a decade, and choosing which one to include in the annual flu vaccine has been a guessing game. Panels of experts choose what strains of the flu they expect to circulate in any given year, and vaccines are manufactured to include those strains. But because vaccine manufacture takes time, the decision must be made months before flu season actually starts.
If a seasonal flu vaccine has a B strain that is mismatched against the circulating strain, it offers little or no protection against disease caused by influenza B. Indeed, the company release noted, "various degrees of mismatch have occurred between the B strain included in trivalent vaccines and the B strain that actually circulated, causing an increased risk of influenza-related morbidity across all age groups -- children, adults and the elderly." In fact, the company noted, in six of the last 11 flu seasons, the predominant circulating influenza B strain was not selected by public health authorities and included in that year's vaccine. The GSK release said the U.S. is the first -- and so far the only -- country to approve its vaccine.
In clinical trials, the company reported, the most common adverse reactions in adults were pain at the injection site, muscle aches, headaches, and fatigue. In children 3 to 18, the most common adverse reactions were pain at the injection site, redness, and swelling, while in children 3 to 6, the most common adverse reactions were drowsiness, irritability, and loss of appetite.
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