One Dose of H1N1 Vaccine Immunogenic in High Percentage of Pregnant Women

Pregnant women, who have been among the most vulnerable to serious health problems associated with the novel influenza A (H1N1) virus, can take some comfort in the protection offered by the H1N1 vaccine.

Initial results from an ongoing clinical trial sponsored by the NIH's National Institute of Allergy and Infectious Diseases, or NIAID, showed that healthy pregnant women mount a robust immune response after a single dose of the vaccine. According to a Nov. 2 NIH news release, the H1N1 flu vaccine elicited an immune response likely to be protective in 92 percent of pregnant women who received a single 15-microgram dose.

The immune response increased to 96 percent in a group of pregnant women that received a single 30-microgram dose.

NIAID director Anthony Fauci, M.D., said in the institute's release that the immune response seen in healthy pregnant women is comparable to that seen in nonpregnant healthy adults. He also said the vaccine used in the trial, which was manufactured by Sanofi Pasteur, has been well tolerated.

The AAFP and other medical professional associations and governmental agencies have urged pregnant women to protect themselves and their infants by being vaccinated for both seasonal influenza and the novel H1N1 flu.

According to the CDC, at least 100 pregnant women have been hospitalized in U.S. intensive care units since the H1N1 outbreak started in the spring. The deaths of 28 pregnant women have been linked to the virus.

Participants in the trial ranged in age from 18-39 years and began the study while in their second or third trimester. The NIAID said no safety concerns related to the vaccine -- which does not include the preservative thimerosal or any adjuvant -- have arisen.