The Centers for Disease Control and Prevention recommends that nursing mothers not receive the smallpox vaccine, even if they are pumping their milk and feeding it to their infant by bottle feeding. If a woman received smallpox vaccine during pregnancy or breastfeeding, she should avoid breastfeeding and handling any baby for at least 3 to 4 weeks until the vaccination scab has separated from the vaccination site. The breasts can be pumped to maintain the milk supply, but the milk should be discarded.[1-3] The newer smallpox and monkeypox vaccine is a live, non-replicating vaccine and is not likely to have these problems during breastfeeding.
If a close contact of the nursing mother receives the smallpox vaccine should wash their hands with soap and warm water after direct contact with the vaccination site, or anything that has touched the vaccination site (bandages, clothing, towels, bedding, etc.). This is will help prevent the spread of vaccinia virus to contacts, including young babies. If a breastfeeding mother who has had close contact with a person recently vaccinated against smallpox develops a rash, she should check with her healthcare provider to determine if the rash is related to the smallpox vaccine. If she has a vaccine-related rash, breastfeeding should not take place until all scabs from the rash have fallen off.[2]