 There are two licensed herpes oaster vaccines, a live vaccine, ZVL, and a recombinant vaccine, RZV. RZV is superior to ZVL in efficacy, has not waned significantly during four years of follow-up and shows higher peak memory and persistence of T cell responses. Immunologic studies also demonstrate the development and persistence of polyfunctional T cell responses in RZV recipients, supporting its higher efficacy over time compared to ZVL. This article was authored by Myron J. Levin and Adriana Weinberg.