Zostavax is a live vaccine eveloped by Merck & Co. which has been shown to reduce the incidence of herpes zoster (known as Shingles) by 51.3% in a pivotal phase III study of 38,000 adults aged 60 and older who received the vaccine. The vaccine also reduced by 66.5% the number of cases of postherpetic neuralgia and reduced the severity and duration of pain and discomfort associated with shingles, by 61.1%.