INTRODUCTION: Prevention of herpes zoster is key to the health and quality of life for almost all senior citizens. A study was performed to evaluate the effectiveness of the herpes zoster vaccines (recombinant zoster vaccine-RZV & zoster vaccine live-ZVL) against the incidence of herpes zoster and postherpetic neuralgia in older adults. According to the authors (Mbinta et al.1), this is the first meta-analysis to assess the effectiveness of herpes zoster vaccines in real-world studies.
DISCUSSION: During varicella-zoster virus (VZV) primary infections, the virus becomes latent in ganglionic neurons. Subclinical reactivation of the latent virus, and exposure to people with varicella or herpes zoster maintains varicella-zoster virus-specific T cell-mediated immunity above the critical threshold. Waning VZV specific T cell-mediated immunity due to immunosenescence and immunosuppressive conditions results in reactivation of latent VZV as herpes zoster (HZ). The authors searched published literature in any language from May 25, 2006 to December 31, 2020. Random-effects meta-analysis models were used to estimate pooled vaccine effectiveness for outcomes of interest (HZ, HZ ophthalmicus, and postherpetic neuralgia) among clinically and methodologically comparable studies. The search identified 1240 studies, of which 1162 were excluded based on title and abstract screening, while an additional 56 were excluded after reading the full text. 22 studies were included in the quantitative analysis, which included 9,536,086 participants. The pooled vaccine effectiveness for ZVL and RZV (respectively) against postherpetic neuralgia was 59.7% vs 76%, against HZ was 45.9% vs 79.3% and 30% vs 66.7% against HZ ophthalmicu. RZV was also effective (75.5%) and recommended in participants who received ZVL within 5 years before receiving RZV. They found lower vaccine effectiveness in all cases than estimates from the meta-analysis of clinical trials. However, an advantage of using real-world data from observational studies is that they were able to summarize longer-term evidence of ZVL vaccine effectiveness waning, which was seen with waning vaccine effectiveness beyond 3 years against HZ. Since RZV was only available since early 2018, further observational studies will be needed to evaluate the degree to which it’s effectiveness wanes over time.
CONCLUSION: Although vaccination with the zoster virus live (ZVL) vaccine was effective in preventing HZ, HZ ophthalmicus and postherpetic neuralgia, it was shown that the recombinant zoster vaccine (RZV) has significantly higher efficacy than ZVL. Using real-world data, they were also able to show the waning effectiveness of ZVL after 3 years. Additional analysis of new data will be needed to determine how effective RZV is longer-term, but from these studies it is suspected that RZV effectiveness will still be higher than ZVL, based on how much stronger the initial vaccine effectiveness is for RZV vs ZVL from the real-world data collected so far.
- Mbinta, J.F., B.P. Nguyen, M. A. Awuni, J. Paynter, and C.R. Simpson. (2022) Post-licensure zoster vaccine effectiveness against herpes zoster and postherpetic neuralgia in older adults: a systemic review and meta-analysis. Lancet Healthy Longev vol 3 issue 4, e263-75. https://doi.org/10.1016/S2666-7568(22)00093-3
MKTG 1077 REV A