Varicella-zoster virus (VZV) is a ubiquitous human pathogen that causes varicella, commonly called chicken pox; establishes latency; and reactivates as herpes tester, referred to as shingles. A live attenuated varicella vaccine, derived from the Oka strain of VZV has clinical efficacy for the prevention of varicella. The vaccine induces persistent immunity to VZV in healthy children and adults. Immunization against VZV also has the potential to lower the risk of reactivation of latent virus. The varicella vaccine may eventually reduce or eliminate herpes tester, which is a serious problem for elderly and immunocompromised individuals.