Various formulations of the live attenuated vaccine, based on the socalled Oka strain of VZV, are in use, both as single antigen and in combination (MMRV). From both a logistic and an epidemiological point of view, the optimal age for varicella vaccination is 12–24 months. In some countries, one dose of the vaccine is considered sufficient, regardless of age. In the United States, two doses, 4–8 weeks apart, are recommended for adolescents and adults. In a few cases (<5%), vaccinees experience a mild varicella-like disease with rash within 4 weeks.
Contraindications to varicella vaccine are pregnancy (because of a theoretical risk to the fetus; pregnancy should be avoided for 4 weeks following vaccination), ongoing severe illness, a history of anaphylactic reactions to any component of the vaccine, and immunosuppression.