Cost-Effectiveness of the Adjuvant Recombinant Zoster Vaccine in Japanese Adults Aged 65 Years and Older

Introduction: The incidence of herpes zoster (HZ) rises steeply after the age of 50 years and the number of HZ cases and complications such as postherpetic neuralgia (PHN) is predicted to increase because of the ageing population. The objective of this study was to estimate the cost-effectiveness of recombinant zoster vaccine (RZV) compared with no vaccine for the Japanese population aged >= 65 years. Methods: A multi-cohort static Markov model with a cycle length of 1 year was used to follow a hypothetical cohort of 1 million people aged >= 65 years over their remaining lifetime. Vaccination at >= 65 years was used in alignment with the influenza and pneumococcal vaccines recommended from 65 years. Japan-specific data inputs for the model were obtained from local data sources. Age-stratified vaccine efficacy and waning rates were based on published clinical trial data. In the base-case analysis, vaccine coverage was assumed to be 40% with a second dose compliance of 95%. Costs and outcomes were discounted at 2% annually and the incremental cost-effectiveness ratio (ICER) was calculated from both a payer's and the societal perspective. Sensitivity analyses were carried out to explore the overall uncertainty in the model. Results: Vaccination with RZV was projected to prevent 48,943 HZ cases and 12,136 PHN cases per million people aged >= 65 years compared with no vaccination. The incremental costs and quality-adjusted life years (QALYs) gained were (sic)9.99 billion and 2314 QALYs from a payer's perspective and (sic)9.34 billion and 2314 QALYs from a societal perspective. The resulting ICERs were approximately (sic)4,320,000 and (sic)4,040,000 per QALY gained from a payer's and the societal perspective, respectively. The ICER remained below a willingness-to-pay threshold of (sic)5,000,000 for most sensitivity analyses carried out. Conclusion: Vaccination against HZ with RZV would be cost-effective compared with no vaccination for the Japanese population aged >= 65 years.