The Global Influenza Initiative recommendations for the vaccination of pregnant women against seasonal influenza.

There is a heavy disease burden due to seasonal influenza in pregnant women, their fetuses, and their newborns. The main aim of this study was to review and analyze current evidence on safety, immunogenicity, and clinical benefits of the inactivated influenza vaccine (IIV) in pregnant women. Current evidence shows that in pregnant women, the seasonal and pandemic IIVs are safe and well tolerated. After vaccination, pregnant women have protective concentrations of anti-influenza antibodies, conferring immunogenicity in newborns. The best evidence, to date, suggests that influenza vaccination confers clinical benefits in both pregnant women and their newborns. Vaccination with either the seasonal or pandemic vaccine has been shown to be cost-effective in pregnancy. There are scarce data from randomized clinical trials; fortunately, new phase 3 clinical trials are under way. In the Northern and Southern Hemispheres, data suggest that the greatest clinical benefit for infants occurs if the IIV is administered within the first weeks of availability of the vaccine, at the beginning of the influenza season, regardless of the pregnancy trimester. The optimal timing to vaccinate pregnant women who live in tropical regions is unclear. Based on evaluation of the evidence, the Global Influenza Initiative (GII) recommends that to prevent seasonal influenza morbidity and mortality in infants and their mothers, all pregnant women, regardless of trimester, should be vaccinated with the IIV. For countries where vaccination against influenza is starting or expanding, the GII recommends that pregnant women have the highest priority.