Herpes Zoster Vaccines

Background Immunization for herpes zoster (HZ) aims to reverse the decline in cell-mediated immunity to varicella zoster virus that occurs with advancing age or immunocompromise. There are 2 vaccines available, one live attenuated (Zoster vaccine, live attenuated [ZVL]) and, recently, a recombinant subunit vaccine (HZ/su). Methods The literature relevant to the two HZ vaccines was reviewed. Results ZVL has overall efficacies of 51% and 65% against HZ and postherpetic neuralgia, respectively, with a prominent decline in efficacy with advancing age of the vaccinee. This compares to approximately 90% efficacy against HZ for HZ/su that is minimally affected with advancing age. The efficacy of ZVL against HZ declines over 4 and 8 years, compared with minimal decline so far over 4 years with HZ/su, and immunogenicity that is maintained for 9 years. Local and systemic reactogenicity to HZ/su is much greater than to ZVL. Conclusions HZ/su establishes an important principle-that a single recombinant viral protein with an effective adjuvant combination can stimulate immunogenicity superior to that of a live attenuated vaccine, and that this can diminish immunosenescence. This provides hope for improvement of other vaccines for aging patients. However, key questions remain unanswered, including the durability of the efficacy of HZ/su, its efficacy as a booster for previous recipients of ZVL, and its efficacy in immunocompromised patients.