Cost-Utility and Budget Impact Analyses of Herpes Zoster Vaccines in Patients With Human Immunodeficiency Virus in Thailand

Objectives

This study aimed to perform cost-utility and budget impact analyses of zoster vaccine live (ZVL) and recombinant zoster vaccine (RZV) compared with no vaccination in patients infected with human immunodeficiency virus (HIV) in Thailand.

Methods

A Markov model was used to estimate costs and outcomes as a quality-adjusted life year from a societal perspective. Costs and outcomes were discounted at 3% per year. Parameters for herpes zoster prevalence and complications were estimated from previous studies. The target population included patients with HIV infection aged ≥18 years with a CD4 count ≥ 200 cells/mm³. Direct medical and nonmedical costs were included in the analysis. Deterministic and probabilistic sensitivity analyses were performed to assess the robustness of the results. A 5-year budget impact analysis of the vaccination program was performed.

Results

The incremental cost-effectiveness ratios of ZVL and RZV compared with no vaccination for patients with HIV infection were $2908.70 and $4391.36 per quality-adjusted life year gain, respectively. ZVL was more likely to be cost-effective. Threshold analysis revealed that RZV could be cost-effective if the cost per dose of RZV was reduced by 0.86%. An additional budget of $15 276 033 for ZVL and $43 338 761 for RZV was estimated to be needed over 5 years.

Conclusions

ZVL is cost-effective at the Thai willingness-to-pay threshold for patients with HIV infection aged ≥18 years with a CD4 count ≥ 200 cells/mm³. RZV needs a 0.86% price reduction to be cost-effective. These findings may be useful in evidence-based policymaking.