H1N1 Vaccine and Pregnant Women

(November 4, 2009) - Early results seem to show that just one dose of the H1N1 flu (Read about "Influenza") vaccine should be enough for most pregnant women. Pregnant women are considered to be one of the groups in the most danger from the H1N1 virus, which is also called the swine flu.

Healthy pregnant women mount a robust immune response (Read about "The Immune System") following just one dose of 2009 H1N1 influenza vaccine, according to initial results from an ongoing clinical trial sponsored by the National Institute of Allergy and Infectious Diseases (NIAID).

"For pregnant women, who are among the most vulnerable to serious health problems from 2009 H1N1 infection, these initial results are very reassuring," says NIAID Director Anthony S. Fauci, MD. "The immune responses seen in these healthy pregnant women are comparable to those seen in healthy adults at the same time point after a single vaccination, and the vaccine has been well tolerated."

According to the Centers for Disease Control and Prevention, since the outbreak began last spring, at least 100 pregnant women have been hospitalized in intensive care units in the United States and at the last official count, 28 pregnant women have died. A preliminary analysis of blood samples taken 21 days post-vaccination from a subgroup of 50 pregnant women participating in the trial shows the following:

• In 25 women who received a single 15-microgram dose of the vaccine, the H1N1 flu vaccine elicited an immune response likely to be protective in 92 percent, or 23 of 25, of these women.
• In 25 women who received a single 30-microgram dose of the vaccine, the H1N1 flu vaccine elicited an immune response likely to be protective in 96 percent, or 24 of 25, of these women.