State of the art: Could nursing mothers be vaccinated with attenuated live virus vaccine?

Recently two cases of vaccine-associated neurologic disease have been reported in breastfed infants whose mothers had received live attenuated yellow fever vaccine. These two cases have focused attention on the transmission of attenuated yellow fever vaccine virus from mother to infant via breastfeeding, and more generally of all other live attenuated viruses used to immunize nursing mothers. This article provides an overview of the rare literature on possible virus excretion in breast milk after vaccination of nursing mothers with live attenuated virus vaccine and on cases of infection via breastfeeding in infants whose mothers had been vaccinated postpartum. Before implementing postpartum vaccination in a nursing mother, the vaccinator needs to weigh up the risk of transmission to and adverse effects in the baby from live vaccine virus against the beneficial effects of the vaccine for the mother, taking into account her need for vaccination.