Pregnancy discovered after smallpox vaccination: Is vaccinia immune globulin appropriate?

Smallpox vaccination just before conception or during pregnancy can result, in rare instances, in fetal vaccinia from viral infection of the fetus. Approximately 50 cases have been documented, despite literally billions of people having been vaccinated. This live viral vaccine has a wider array of rare but serious medical side effects (eg, eczema vaccinatum, progressive vaccinia, encephalitis, myopericarditis) compared with other vaccines that are given currently to the public. In response to recent world events, the Centers for Disease Control and Prevention and the United States Department of Defense established a preoutbreak smallpox vaccination program. Because no actual outbreak has yet occurred, some investigators have proposed prophylactic treatment with vaccinia immune globulin for pregnancies that are exposed to smallpox vaccine to prevent fetal vaccinia. We review the existing medical literature to access the risks of fetal vaccinia in these pregnancies and the controversy regarding the prophylactic use of vaccinia immune globulin.