Flu vaccine seems to work for kids under 6 months of age

From Toronto, at a meeting of the Infectious Diseases Society of America

Babies younger than 6 months appear fully capable of responding to a flu shot, researchers find.

Such infants aren’t typically vaccinated when influenza season arrives each fall, even though they routinely receive other vaccinations beginning at age 2 months. In the United States, flu shots are recommended for all children ages 6 months to 5 years.

“Children under the age of 6 months have actually the highest rate of [flu] hospitalization of any age group,” says physician Janet A. Englund of the University of Washington in Seattle. “But there is no licensed vaccine for this group and no antiviral therapy available for them.”

Englund and her colleagues randomly assigned 1,376 healthy infants, ages 6 to 12 weeks, to get either two doses of last year’s flu vaccine or two inert injections. In both cases, the shots were 1 month apart.

Englund reported that a month after the second shot, blood analysis showed that 86 percent of the babies getting the vaccine had mounted an active antibody response against the H3N2 strain, and 50 percent had responded to the H1N1 strain. Those are the two most common strains affecting people. Babies receiving the placebo injections failed to make antibodies. The infants in the vaccine and placebo groups showed equal incidences of side effects, such as fever and irritation at the injection sites.

None of the babies developed 100 percent immunity, notes Kathleen M. Neuzil, a University of Washington physician, who has worked with Englund but didn’t participate in this study. “But it’s better than nothing, and what we’re doing right now is nothing.”