FluMist OKd for kids as young as 2

The U.S. Food and Drug Administration last week expanded the use of the flu vaccine FluMist to include children as young as 2.

FluMist is the only nasal spray vaccine for influenza prevention and relies on a mixture of live, but weakened viruses. The viruses are not infectious, but the body’s immune system can recognize surface proteins on the pathogens to mount a response against them.

Federal regulators considered evidence from a large clinical study before expanding the age group eligible for the vaccine. Before Wednesday’s decision, the nasal spray vaccine was approved for use in people 5 to 49.

However, in a study of 4,000 children between the ages of 2 and 5 during the 2004-2005 flu season, there was a 54% reduction in influenza cases among those who received FluMist. Researchers compared that finding with children of the same age who had received a traditional flu shot. The study is one of 48 safety trials, which have involved nearly 50,000 participants, ranging from 6 weeks to 90 years old.

Manufactured by MedImmune, a biotechnology company in Gaithersburg, Md., FluMist was licensed by the FDA in 2003. Since then, 60,000 doses have been administered. The vaccine is designed to prevent three circulating strains, as does the traditional flu shot: two A strains and one B strain.

Using live but weakened viral strains theoretically stimulates a more vigorous immune response to keep the flu at bay. In the traditional flu shot, the viruses have been killed.

The Centers for Disease Control and Prevention strongly recommends flu vaccinations. Each year, an estimated 60 million Americans catch the flu; 200,000 are hospitalized and 36,000 die, most of them infants and elderly people.