Cost Effectiveness and Budget Impact of the Recombinant Zoster Vaccine Among Older Adults in Singapore

OBJECTIVES: This study evaluates the cost effectiveness and budget impact of the recombinant zoster vaccine (RZV) for preventing herpes zoster (HZ) and its associated complications, including post-herpetic neuralgia (PHN), among older adults in Singapore.

METHODS: A cost-utility analysis using a static Markov cohort model was performed, to evaluate the cost-effectiveness of RZV vaccination versus no vaccination in immunocompetent adults aged 50 years and older. The analysis was conducted from the Singapore healthcare system perspective, over a 30-year time horizon. The model used vaccine efficacy from ZOE-50, ZOE-70 and ZOSTER-049 studies and local HZ incidence rates. Costs and healthcare resource utilisation were obtained from local public healthcare institutions and clinical experts. The vaccine cost was based on an average of overseas and local prices. Sensitivity and scenario analyses were performed to assess model uncertainties. Additionally, an epidemiological-based budget impact analysis was performed to estimate the financial impact to the healthcare system.

RESULTS: Compared to no vaccination, the RZV resulted in a high base case incremental cost-effectiveness ratio (ICER) of over SGD 120,000 (USD 88,884) per quality-adjusted life-year (QALY) gained. Given the low mortality risk with HZ, the incremental QALYs were driven mainly by the QALY gains from the reduced incidences of HZ and PHN. While additional analysis indicated that the ICER was the lowest in the age subgroup of 65 years and older, it remained over SGD 90,000 (USD 66,663) per QALY gained. ICER results were most sensitive to the incidence rate of HZ, discount rate, and disutility values associated with HZ and PHN. The budget impact analysis on vaccine costs estimated a 5-year expenditure of $93.3M, based on a conservative assumption that population coverage rate reaches 20% after 5 years.

CONCLUSIONS: In Singapore, the RZV is unlikely to represent good value, even in older age cohorts.