Co-administration of vaccines in pregnancy: unique challenges and knowledge gaps.

Vaccination in pregnancy directly protects the mother and can prevent serious infections in early life. There are an increasing number of vaccines that are recommended during pregnancy and deployed in a growing number of countries. However, most recommendations for administration of these vaccines in pregnancy are based on studies that investigate one vaccine at a time. Largely lacking are data on the impact of co-administration including spacing and timing of the multiple vaccines during pregnancy on safety, efficacy and immunogenicity. We here place what is known into the context co-administration of vaccines with focus on the mother as well as the infant.