Optimizing benefits of influenza virus vaccination during pregnancy: potential behavioral risk factors and interventions.

Pregnant women and infants are at high risk for complications, hospitalization, and death due to influenza. It is well-established that influenza vaccination during pregnancy reduces rates and severity of illness in women overall. Maternal vaccination also confers antibody protection to infants via both transplacental transfer and breast milk. However, as in the general population, a relatively high proportion of pregnant women and their infants do not achieve protective antibody levels against influenza virus following maternal vaccination. Behavioral factors, particularly maternal weight and stress exposure, may affect initial maternal antibody responses, maintenance of antibody levels over time (i.e., across pregnancy), as well as the efficiency of transplacental antibody transfer to the fetus. Conversely, behavioral interventions including acute exercise and stress reduction can enhance immune protection following vaccination. Such behavioral interventions are particularly appealing in pregnancy because they are safe and non-invasive. The identification of individual risk factors for poor responses to vaccines and the application of appropriate interventions represent important steps towards personalized health care.