Herpes ZosterOverall, 9454 healthy children (12 months to 12 years of age) and 1648 adolescents and adults (13years of age and older) have been vaccinated with VARIVAX in clinical trials. Eight cases of herpeszoster have been reported in children during 42,556 person-years of follow-up in clinical trials, resulting ina calculated incidence of at least 18.8 cases per 100,000 person-years. The completeness of thisreporting has not been determined. One case of herpes zoster has been reported in the adolescent andadult age group during 5410 person-years of follow-up in clinical trials, resulting in a calculated incidenceof 18.5 cases per 100,000 person-years. All 9 cases were mild and without sequelae. Two cultures (onechild and one adult) obtained from vesicles were positive for wild-type VZV as confirmed by restrictionendonuclease analysis {11}. The long-term effect of VARIVAX on the incidence of herpes zoster,particularly in those vaccinees exposed to wild-type varicella, is unknown at present.In children, the reported rate of herpes zoster in vaccine recipients appears not to exceed thatpreviously determined in a population-based study of healthy children who had experienced wild-typevaricella {12}. The incidence of herpes zoster in adults who have had wild-type varicella infection is higherthan that in children. http://www.merck.com/product/usa/pi_circulars/v/varivax/varivax_pi.pdf