Persistence of Varicella-Zoster Virus Cell-Mediated Immunity After the Administration of a Second Dose of Live Herpes Zoster Vaccine.

Protection against zoster conferred by zoster vaccine live (ZVL; Zostavax) wanes over time. We compared varicella-zoster virus cell-mediated immunity (VZV-CMI) of adults ≥70 years who received a second dose of ZVL ≥10 years after the initial dose with de novo-immunized age-matched controls. Before and during the first year after vaccination, VZV-CMI was significantly higher in reimmunized compared with de novo vaccinees. At 3 years, VZV-CMI differences between groups decreased and only memory responses remained marginally higher in reimmunized participants. In conclusion, the increase in VZV-CMI generated by reimmunization with ZVL is at least equally persistent compared with de novo immunization.