Flu Vaccine Safe Throughout Pregnancy

Oct. 30, 2009 (Philadelphia) -- Pregnant women who get the flu vaccine are less likely to have babies who are premature, small for their gestational age, or who have to be hospitalized, according to three new studies.

A fourth study shows that the vaccine is safe throughout pregnancy -- even during the third trimester.

Experts meeting at the annual meeting of the Infectious Diseases Society of America (IDSA) say they hope the findings will convince more pregnant women to get a flu shot.

"The studies emphasize the importance of vaccination during pregnancy not only for the benefit of the mom, but for the baby," says Vanderbilt University's William Schaffner, MD, head of the IDSA's immunization work group.

Schaffner, who moderated a news conference to discuss the findings, tells WebMD that vaccination rates during pregnancy are "dismal. One estimate says that only 25% of pregnant women [get a flu shot]. That means that three in four don't."

While the studies did not involve women vaccinated with the H1N1 swine flu vaccine, Bruce Gellin, MD, MPH, director of the Health and Human Services Department National Vaccine Program Office, notes that the swine flu vaccine is made exactly the same way as the seasonal flu vaccine and there are no differences in terms of safety.

One of the new studies, presented by Yale University's Marietta Vazquez, MD, shows that infants born to vaccinated women are less likely to be hospitalized with the flu.

The study involved more than 100 infants who were hospitalized with lab-confirmed influenza during their first year of life. Their moms' vaccination rates were compared with those of the mothers of more than 200 babies who were admitted to the hospital for reasons other than the flu.

Only 5% of the women who had an infant with the flu had been vaccinated, compared with 16% of the mothers whose babies did not have influenza.

"Vaccination in pregnancy decreased by 80% the chance that the baby would be hospitalized with the flu in the first 12 months of life. It was 89% effective in preventing hospitalization in the first six months," she tells WebMD.