Competing biomedical HIV prevention strategies: potential cost‐effectiveness of HIV vaccines and PrEP in Seattle, WA

INTRODUCTION: Promising HIV vaccine candidates are steadily progressing through the clinical trial pipeline. Once available, HIV vaccines will be an important complement but also potential competitor to other biomedical prevention tools such as pre‐exposure prophylaxis (PrEP). Accordingly, the value of HIV vaccines and the policies for rollout may depend on that interplay and tradeoffs with utilization of existing products. In this economic modelling analysis, we estimate the cost‐effectiveness of HIV vaccines considering their potential interaction with PrEP and condom use. METHODS: We developed a dynamic model of HIV transmission among the men who have sex with men population (MSM), aged 15‐64 years, in Seattle, WA offered PrEP and HIV vaccine over a time horizon of 2025‐2045. A healthcare sector perspective with annual discount rate of 3% for costs (2017 USD) and quality‐adjusted life years (QALYs) was used. The primary economic endpoint is the incremental cost‐effectiveness ratio (ICER) when compared to no HIV vaccine availability. RESULTS: HIV vaccines improved population health and increased healthcare costs. Vaccination campaigns achieving 90% coverage of high‐risk men and 60% coverage of other men within five years of introduction are projected to avoid 40% of new HIV infections between 2025 and 2045. This increased total healthcare costs by $30 million, with some PrEP costs shifted to HIV vaccine spending. HIV vaccines are estimated to have an ICER of $42,473/QALY, considered cost‐effective using a threshold of $150,000/QALY. Results were most sensitive to HIV vaccine efficacy and future changes in the cost of PrEP drugs. Sensitivity analysis found ranges of 30‐70% HIV vaccine efficacy remained cost‐effective. Results were also sensitive to reductions in condom use among PrEP and vaccine users. CONCLUSIONS: Access to an HIV vaccine is desirable as it could increase the overall effectiveness of combination HIV prevention efforts and improve population health. Planning for the rollout and scale‐up of HIV vaccines should carefully consider the design of policies that guide interactions between vaccine and PrEP utilization and potential competition.