Immune senescence and vaccines to prevent herpes zoster in older persons

► Latent VZV is maintained in sensory neurons because of VZV-specific T-cell immunity. ► This immunity declines with age - the number/function of early effectors and effector memory. ► The loss of this T-cell immunity correlates with the occurrence of herpes zoster. ► A herpes zoster vaccine can restore this immunity and prevent herpes zoster. ► Suggestions are offered to improve the efficacy of zoster vaccine.