Pregnant women have strong response to 1 dose of H1N1 vaccine

Healthy pregnant women mount a robust immune response 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 of the National Institutes of Health.

“For pregnant women, who are among the most vulnerable to serious health problems from 2009 H1N1 infection, these initial results are very reassuring,” said Anthony S. Fauci, director of the NIAID. “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.

The trial began Sept. 9 and reached its target enrollment of 120 volunteers in mid-October. All participants are between 18 to 39 years old and began the study in their second or third trimester (14 to 34 weeks) of pregnancy.

To date, the vaccine appears to be well-tolerated, and no safety concerns related to the vaccine have arisen. 

The vaccine used in this clinical trial was manufactured by Sanofi Pasteur at its plant in Swiftwater, Pa., in the same manner as the company’s injectable seasonal influenza vaccine. Like the seasonal flu vaccine, the 2009 H1N1 flu vaccine contains a purified portion of the killed virus and therefore cannot cause infection. The vaccine does not contain the preservative thimerosal or an immune boosting substance known as an adjuvant.

Organizations in this Story

National Institutes of Health

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