evidence: In 2006, on the basis of the findings from the Shingles Prevention Study, [122] the US Food and Drug Administration (FDA) approved Zostavax for prevention of herpes zoster in people aged 60 years and older. This randomized, double-blind, placebo-controlled trial of the vaccine enrolled more than 38,000 adults older than 60 years. The vaccine reduced the incidence by 61.1% and the incidence of PHN by 66.5%. [...] The first trial, ZOE-50, was a randomized, placebo-controlled study conducted in 18 countries in Europe, North America, Latin America, and Asia-Australia. The study evaluated the efficacy, immunogenicity, and safety of the HZ/su vaccine in adults aged 50 years or older. Participants were randomly assigned in a 1:1 ratio to receive either HZ/su vaccine (0.5 mL at month 0 and 2) or placebo. Two doses of HZ/su administered 2 months apart had a vaccine efficacy of 97.2%, compared with placebo, in reducing the risk of herpes zoster in adults aged 50 years or older. The vaccine efficacy was similar among the three age groups. [132]