FDA approves first quadrivalent influenza vaccine

The U.S. Food and Drug Administration has approved FluMist Quadrivalent, a vaccine to prevent seasonal influenza in people between the ages of two and 49 years of age.

The influenza vaccine is the first to contain four influenza virus strains - two influenza A strains and two influenza B strains. The quadrivalent vaccine is similar to the already approved trivalent FluMist, which contains weakened forms of the virus strains and is administered as a nose spray.

"Illness caused by Influenza B virus affects children, particularly young and school-aged, more than any other population," Karen Midthun, the director of the FDA's Center for Biologics Evaluation and Research, said. "A vaccine containing the four virus strains most likely to spread and cause illness during the influenza season offers an additional option to aid in influenza prevention efforts."

The influenza A and B viruses are the two strains that cause illness and death in humans. The annually FDA-approved seasonal influenza vaccine contains three strains of influenza virus - two A strains and one B strain. By including a second B strain, the quadrivalent vaccine may increase the likelihood of adequate prevention against B strains that circulate that aren't in the annual vaccine.

FluMist Quadrivalent is manufactured in Gaithersburg, Maryland, by MedImmune LLC.