The Centers for Disease Control and Prevention and American Academy of Pediatrics state that vaccines given to a nursing mother do not affect the safety of breastfeeding for mothers or infants and that breastfeeding is not a contraindication to poliovirus vaccine. The injectable polio vaccine now recommended in the United States is inactivated and poses no risk when given to mothers who are breastfeeding.[1,2] Breastfeeding also appears to reduce infant side effects associated with routine childhood immunization and can reduce the efficacy of oral polio vaccines.[3] However, some studies indicate that breastfeeding might improve infant response to oral polio vaccine.[4,5] Breastfed infants should be vaccinated according to the routine recommended schedules. Exclusive breastfeeding improves the response to oral polio vaccine in countries with poor infant nutrition and high rates of infant diarrhea.