An Evaluation of the Epidemiology, Vaccine Effectiveness and Vaccine Safety of Herpes Zoster Vaccination
Background Herpes zoster is characterised by a painful vesicular rash and, in older people, often leads to post-herpetic neuralgia and prolonged pain with a subsequent negative impact on quality of life and functional status. Herpes zoster vaccines have been demonstrated to be effective and safe. The objective was to evaluate the epidemiology of herpes zoster, vaccine effectiveness and vaccine safety of herpes zoster vaccination.
Methods A systematic review and meta-analysis were carried out to evaluate the international evidence on the effectiveness of zoster vaccines. National retrospective observational cross-sectional (2006–2018), retrospective matched cohort (2018–2021), and self-controlled case series (2018–2021) studies were carried out using routinely collected data from the Ministry of Health, New Zealand. Adjusted ratios were determined using appropriate regression models. Adjusted ratios were used to estimate vaccine effectiveness, and vaccine safety was evaluated using pre-specified serious adverse events.
Results Thirteen articles were included in the meta-analysis. The overall quality of evidence was very low for all outcomes. The pooled vaccine effectiveness for zoster vaccine live against herpes zoster in adults was 45.9% (95% confidence interval [CI]:42.2–49.4), and against postherpetic neuralgia, was 59.7% (95% CI: 58.4–89.7). The pooled vaccine effectiveness for recombinant zoster vaccine against herpes zoster in adults was 79.2% (95% CI: 57.6–89.7).
A total of 10,865 herpes zoster hospitalisations, 203,021 community herpes zoster, and 2,304 postherpetic neuralgia hospitalisations were identified between 2006 and 2018. The incidence of herpes zoster was 3.68 (95% CI: 3.67–3.70) per 1,000 population, and the incidence of hospitalised postherpetic neuralgia was 0.04 (95% CI: 0.038–0.041) per 1,000 population.
A total of 824,142 (274,272 vaccinated with the zoster vaccine live matched with 549,870 unvaccinated) adults were included in the study. The vaccine effectiveness against hospitalised herpes zoster and postherpetic neuralgia was 57.8% (95% CI: 41.1–69.8) and 73.7% (95% CI:14.0–92.0), respectively. The vaccine effectiveness against community herpes zoster was 30.0% (95% CI: 25.6–34.5).
During the follow-up period, 1082 (0.4%) vaccinated people were hospitalised for the pre-specified adverse event during the at-risk and control windows and included in the study population. Overall, the rate ratio of serious adverse events following immunisation was 0.43 (95% CI: 0.37–0.50). There was no significant increase in the risk of cerebrovascular accidents (rate ratio = 0.46; 95% CI: 0.36–0.56), acute myocardial infarction (rate ratio = 0.28; 0.16–0.47), acute pericarditis (rate ratio = 0.44; 95% CI: 0.12–1.33), acute myocarditis (rate ratio = 0.21; 95% CI: 0.01–2.12) and Ramsay–Hunt Syndrome (rate ratio = 0.79; 95% CI: 0.11–5.68) in the at-risk period compared to the control period (background level).
Conclusion Herpes zoster and postherpetic neuralgia affect all population groups, and the incidence increases with age. Herpes zoster vaccines are safe and effective in preventing herpes zoster and associated complications in routine clinical practice.
