Secondary
objectives included determining the vaccine
efficacy in reducing the incidence of herpes zoster
in each age group (50 to 59 years, 60 to 69
years, and ≥70 years) and HZ/su safety and reactogenicity
profiles. (A complete list of study objectives
is provided in the Supplementary Appendix.)
Vaccine efficacy, as a percentage, was
defined as 1 minus the ratio of the incidence of
herpes zoster in the HZ/su group to the incidence
in the placebo group, multiplied by 100.