Herpes zoster (HZ) and post-herpetic neuralgia (PHN) are frequently occurring diseases in elderly and in immuno-compromised persons. The live attenuated HZ vaccine boosts an existing immune response, so that the already established varicella-zoster virus infection is kept latent. Vaccination has been shown to halve the risk of HZ, and the risk of PHN is reduced by two thirds in people = 60 years. The vaccine is approved for persons aged = 50 years. However, the clinical efficacy of the vaccine is best studied in people aged = 60 years. The vaccine has so far not shown any serious side-effects.