If a woman receives varicella vaccine and subsequently finds out that she is pregnant, what should she be told about the risk to the fetus?
Since the risk of congenital varicella syndrome following natural infection is 0.4-2.0%, the risk of congenital anomalies following vaccination with attenuated varicella vaccine is likely to be lower or absent. In order to clarify this risk, Merck and Co., Inc., in collaboration with CDC, has established a Varicella Vaccine in Pregnancy Registry, similar to that which was established for rubella vaccine during pregnancy. So far, there have been no cases of congenital varicella syndrome reported to the registry however the number of women followed so far precludes excluding a very low risk. We encourage enrollment of women who were given varicella vaccine inadvertently during pregnancy. Women may be enrolled in the registry by calling 1-800-986-8999.