Previous studies have found that the protection against herpes zoster (HZ) induced by the live attenuated zoster vaccine Zostavax (ZVL) wanes within 3-7 years. The authors were interested in whether revaccination with the adjuvanted HZ subunit vaccine candidate (HZ/su) induces comparable immune responses in previous ZVL recipients and ZVL-naive participants (HZ-NonVac). They performed an open-label study where adults ≥65 years who were vaccinated with ZVL ≥5 years previously (HZ-PreVac) were matched to ZVL-naive adults (HZ-NonVac). All participants received two doses of HZ/su 2 months apart. In the 430 participants recruited, the humoral immune response to HZ/su was found to be noninferior in HZ-PreVac compared with HZ-NonVac (adjusted geometric mean concentration ratio 1.04, 95%CI 0.92-1.17). Cellular immunogenicity, reactogenicity and safety appeared to be similar between the two groups. HZ/su was well-tolerated, with no safety concerns raised within 1 month of the second post-dose. Therefore HZ/su induces a strong immune response irrespective of prior vaccination with ZVL and therefore may be an attractive option to revaccinate prior ZVL recipients.
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