If a person receives varicella vaccine and subsequently confirms pregnancy, what should the person be told about the risk to the fetus?

To date, no adverse outcomes of pregnancy or in a fetus have been reported among people who inadvertently received varicella vaccine shortly before or during pregnancy. The risk of congenital varicella syndrome following varicella disease is small, so the risk of congenital anomalies following vaccination with live attenuated varicella zoster virus (VZV)-containing vaccine is probably very small.

Merck and the Centers for Disease Control and Prevention (CDC) jointly operated a pregnancy registry for women exposed to VZV-containing vaccines for seventeen years after the licensure of varicella vaccine. The registry was discontinued in 2013, having found no signals to indicate a risk of Congenital Varicella Syndrome or pattern of birth defects related to vaccination with VZV-containing vaccines. Healthcare providers may continue to report exposure to VZV-containing vaccines within 3 months of conception or during pregnancy by contacting Merck’s call center at 1-877-888-4231.