Denise J. Jamieson, Dmitry M. Kissin, Carolyn B. Bridges, Sonja A. Rasmussen

Influenza vaccination is a cornerstone of influenza prevention efforts among pregnant women. Prior to 2005, data from studies conducted on pregnant women were limited, with much of the supporting evidence coming from influenza vaccine studies conducted among nonpregnant, age-matched populations. Since 2005, however, an increasing number of studies have demonstrated the safety and immunogenicity of influenza vaccine for pregnant women, including evidence of maternal transfer of antibody. In addition, the clinical benefit of influenza vaccination, both for the mother and infant, was demonstrated in a landmark randomized clinical trial conducted in Bangladesh. Additional randomized clinical trials with laboratory-confirmed influenza as the primary outcome are underway in countries without a current influenza vaccination program, but such trials are unlikely to be conducted in the United States or other countries that already recommend the vaccination of pregnant women. However, current evidence supports the safety and immunogenicity of inactivated influenza vaccine and its effectiveness in reducing the risk of influenza-related illness among pregnant women.