National Smallpox Vaccine in Pregnancy Registry

Smallpox vaccine is known to cause fetal vaccinia, a very rare but serious complication of exposure to smallpox vaccine during pregnancy. Fewer than 50 cases have been reported (1--3), three of which occurred in the United States in 1924, 1959, and 1968. Affected pregnancies have been reported in women vaccinated in all three trimesters, in primary vaccinees, and in those being revaccinated, and in nonvaccinated contacts of vaccinees. Because a risk for infection to the fetus is possible in the pre-event setting, smallpox vaccination is not recommended for pregnant women or anyone with close physical contact to a pregnant woman (e.g., a household member or sex partner).