Update on varicella vaccine.

A live varicella vaccine has been licensed in Japan, Korea, some European countries, and the United States. Susceptible children can receive varicella vaccine at 12 to 18 months of age, and those who lack a reliable history of chickenpox should be immunized between 11 and 12 years of age. Susceptible children 13 years of age or older should receive two doses at least 1 month apart. Varicella vaccine administered under routine conditions has been proved to be highly effective. Varicella immunization has induced long-term humoral and cellular immunity. The varicella vaccine can be given in immunocompromized children, including children with leukemia and bone marrow transplantation recipients, when immune function recovers. Inactivated varicella vaccine can also reduce morbidity due to varicella zoster virus reactivation in high-risk populations.