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Varivax (varicella virus vaccine live [Oka/Merck]; Merck), a live attenuated varicella vaccine, is indicated for vaccination against varicella in appropriate individuals > or =12 months of age. The 10-year safety profile for Varivax is described using data submitted to Merck from routine global postmarketing surveillance, combined with information from a Varicella Zoster Virus Identification Program, which uses polymerase chain reaction (PCR) analysis to identify the presence and strain of VZV in selected specimens. There were 16,683 reports worldwide voluntarily submitted to Merck, for an overall reporting rate of 3.4 reports/10,000 doses of vaccine distributed. PCR analysis of vesicular rashes that occurred within the first 2 weeks after vaccination was more likely to identify wild-type varicella-zoster virus (VZV), whereas the presence of Oka VZV was generally associated with vesicular rashes that occurred 15-42 days after vaccination. Reports of breakthrough varicella that occurred >42 days after vaccination were associated with wild-type VZV. Among 697 herpes zoster reports, PCR analysis identified Oka VZV in 57 reports and wild-type VZV in 38 reports. There were no primary neurologic adverse events associated with Oka VZV. Secondary transmission of Oka VZV from vaccine recipients with postvaccination vesicular rashes was identified in 3 susceptible household contacts. Disseminated Oka VZV was identified in 6 immunocompromised patients and 1 patient with Down syndrome. This review has shown that the vaccine is generally safe and well tolerated.

Background: The Pregnancy Registry for Varivax (Merck) was established to monitor for congenital varicella syndrome or other birth defects in the offspring of women who were exposed to varicella vaccine while pregnant., Methods: The registry receives voluntary reports from health care providers or consumers about women given the vaccine 3 months before or during pregnancy. Follow-up is conducted to obtain and classify pregnancy outcomes. All reports are evaluated for the presence of birth defects. Outcomes from prospectively reported pregnancy exposures are used to calculate rates and 95% confidence intervals., Results: From 17 March 1995 through 16 March 2005, 981 women were enrolled. Pregnancy outcomes were available for 629 prospectively enrolled women. Among the 131 live births to varicella-zoster virus-seronegative women, there was no evidence of congenital varicella syndrome (rate, 0% [95% confidence interval [CI], 0%-6.7%]), and major birth defects were observed in 3 infants (rate, 3.7% [95% CI, 0.8%-10.7%])., Conclusions: Although the numbers of exposures are not sufficient to rule out a very low risk, data collected in the pregnancy registry to date do not support a relationship between the occurrence of congenital varicella syndrome or other birth defects and varicella vaccine exposure during pregnancy.