Herpes zoster (also called shingles) is a condition in which painful blisters develop on the skin along the path of a nerve. Shingles results from infection with the varicella zoster virus (the same virus that causes chickenpox). After chickenpox, the virus remains inactive in nerves. Years later, shingles develops when the virus becomes active during periods of illness or stress. People usually recover from shingles in a few weeks, but up to half of people develop lasting pain in the affected area. This pain is known as postherpetic neuralgia. Shingles becomes more common with older age. A 2005 study showed that the varicella zoster virus vaccine reduces the occurrence of shingles when given to people 60 years of age or older. We do not know whether the costs of the vaccine are worth the potential benefits.