Cost-effectiveness of Recombinant Zoster Vaccine (RZV) and Varicella Vaccine Live (VVL) against herpes zoster and post-herpetic neuralgia among adults aged 65 and over in Japan.

Background: The approval of the extended use of 1-dose varicella vaccine (VVL) in adults aged 50 and older against herpes zoster (HZ) in 2016 and the 2-dose recombinant zoster vaccine (RZV) in 2018 raised the need to evaluate the value for money between these two vaccines.
Methods: We conducted a cost-effectiveness analysis with Markov modelling to evaluate the efficiency of the immunisation programmes from payer's perspective. Eight strategies with different ages to receive VVL or RZV were set, namely: 65-84 year old (y.o.), 70-84 y.o., 75-84 y.o., and 80-84 y.o. VVL- or RZV-strategy. Incremental cost-effectiveness ratios (ICERs) compared with curative care scenario were calculated. The health statuses following the target cohort were as follows: acute HZ followed by recovery, post-herpetic neuralgia followed by recovery, post HZ/PHN, recurrence of HZ, and general death.
Results: At the vaccination cost ¥8000 (US$73) for 1-dose ZVL and ¥30,000 (US$273) for 2-dose RZV, ICERs ranged from ¥2,633,587/US$23,942 (age 80-84 y.o.) to ¥3,434,267 or US$31,221 (age 65-84 y.o.)/QALY gained for VVL-strategies; from ¥5,262,227 or US$47,838 (age 80-84 y.o.) to ¥6,278,557 or US$57,078/QALY gained (age 65-84 y.o.) for RZV-strategies. Cost-effectiveness acceptability curves derived from probabilistic sensitivity analyses showed that if the cost-effective threshold was at ¥3,000,000 or US$27,273/QALY, the acceptability was 90.7% and 8.8% for 65-84 VVL-strategy and 65-84 RZV-strategy, respectively; if at ¥5,000,000 or US$45,455/QALY, 56.2% and 43.8%, and if at ¥10,000,000 or US$90,909/QALY 11.9% and 88.1%, respectively.
Conclusion: Vaccinating individuals aged 65-84 y.o., 70-84 y.o., 75-84 y.o., 80-84 y.o. with VVL or RZV to prevent HZ-associated disease in Japan can be cost-effective from payer's perspective, with vaccination costs at ¥8,000 per shot for VVL, ¥30,000 for 2-dose RZV. While the results suggesting that only 65-84 VVL-strategy and 65-84 RZV strategy should be considered when introducing HZ immunisation programme. The optimal strategy varies depending on the willingness-to-pay threshold.
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