FluMist Quadrivalent is the first vaccine to contain four strains of the influenza virus - two influenza A strains and two B strains. It is manufactured by Gaithersburg-based MedImmune LLC.
The new vaccine containst weakened forms of the virus strains and is administered by a spray into the nose.
Prior to approval of the new drug, other vaccines contained three strains of flu - two A and one B. The addition of a B strain increases the likelihood of protection, the FDA said.
Illnesses caused by the B virus are more likely to infect young, school-age children more than any other population, the FDA said.
The FDA said vaccine is the best prediction against influenza, which can be unpredictable and sometimes deadly.
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