This is a randomized, placebo-controlled phase 3 trial that was conducted in 18 countries involving adults 70 years of age or older. The study’s primary objective was to evaluate the efficacy of Hz/su, as compared with placebo, in reducing the risk of herpes zoster among adults 70 years of age or older. A pooled analysis was also conducted involving participants from ZOE-50 (an earlier trial of the same vaccine in adults 50 years of age and older) and ZOE-70 to evaluate the efficacy of the vaccine as compared with placebo in reducing the risk of herpes zoster and the risk of postherpetic neuralgia in the overall population of participants 70+ years from both studies.The trial had a total of 13,900 participants and found:

• The incidence of herpes zoster per 1000 person-years was 0.9 in the vaccinated group and 9.2 in the placebo group for an overall vaccine efficacy of 89.5%
• Vaccine efficacy did not differ significantly between the two age groups – 90% among participants 70-79 years and 89.1% among participants ≥ 80 years-old
• The incidence of postherpetic neuralgia per 1000 person-years was 0.1 in the vaccinated group and 0.9 in the placebo group for an overall vaccine efficacy of 91.2%
• The incidence of serious adverse events were similar in the two study groups, occurring in 16.6% of vaccine recipients and 17.5% of placebo recipients

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