Influenza in Infants Born to Women Vaccinated During Pregnancy

This cohort study to compare influenza outcomes of infants less than 6 months of age born to vaccinated and unvaccinated women included more than 245,000 women who delivered nearly 250,000 infants in a single health system between December 2005 and March 2014. The authors found that while only 10% of pregnant women were vaccinated during the overall course of the study, the proportion steadily increased to 52% in the final season. They also found a 64% reduction in influenza-like illness health encounters, a 70% reduction in laboratory-confirmed influenza, and an 81% reduction in hospitalization with laboratory-confirmed influenza in infants born to women who reported being vaccinated during pregnancy and 97% of laboratory-confirmed influenza in infants less than 6 month occurred in those born to women who did not report being vaccinated during pregnancy.