Participant disposition. Potential participants were first screened and matching variables were collected (see Figure 1). Only matched participants were vaccinated with herpes zoster subunit candidate vaccine (see Supplementary Table 1 for additional information on matching). Abbreviations: HZ-NonVac, participants who never received the live attenuated zoster vaccine; HZ-PreVac, participants who received live attenuated zoster vaccine ≥5 years prior to study start; SAE, serious adverse event.