Cost thresholds for anticipated long-acting HIV pre-exposure prophylaxis products in Eastern and Southern Africa: a mathematical modelling study

Introduction

Affordable HIV prevention tools are needed in Eastern and Southern Africa (ESA). Several promising long-acting pre-exposure prophylaxis (LA-PrEP) products are available or in development. However, ESA settings face severe healthcare resource constraints. We aimed to estimate the threshold price at which LA-PrEP products could be cost-effective in three ESA settings.

Methods

We adapted an agent-based model, EMOD-HIV, to simulate LA-PrEP (monthly oral, 2- and 6-monthly injectable) rollout in South Africa, Zimbabwe and Kenya. Due to uncertainties about LA-PrEP use, we examined a range of coverages (5%−20% of HIV-negative sexually active adults) and extents to which LA-PrEP use will be concentrated among those most at risk (prioritized rollout from higher- to lower-risk groups vs. uniform rollout among sexually active adults). To evaluate a 20-year commitment to LA-PrEP delivery, we assumed LA-PrEP was scaled up to target coverage from 2025 to 2030 and maintained at target levels before ending in 2045. We estimated maximum per-dose and per-year LA-PrEP costs that achieve cost-effectiveness (<US$500 per disability-adjusted life-year averted) over 35 years (until 2060), compared to a scenario of daily oral PrEP only. Sensitivity analyses varied PrEP scale-up speeds and eligible populations.

Results

Risk-prioritized LA-PrEP for 5% of adults was projected to avert 11–21% of HIV acquisitions across settings, with 3–5 times more HIV acquisitions averted and 3–5 times higher maximum cost compared to non-prioritized rollout. Six-monthly injectable PrEP supported the highest per-dose cost: in the scenario with the most cost-effective LA-PrEP use (5% risk-prioritized rollout), the maximum per-dose price in South Africa was $52.99 (95% CI: $48.82–$57.21), in Zimbabwe $14.64 (95% CI: $12.04–$17.38) and in western Kenya $7.50 (95% CI: $6.73–$8.27). For monthly oral PrEP, corresponding per-dose costs were $5.02 (95% CI: $4.67–$5.37), $1.45 (95% CI: $1.10–$1.79) and $0.87 (95% CI: $0.80–$0.93). Results were sensitive to eligible population and prioritization, and moderately sensitive to scale-up speed and product effectiveness.

Conclusions

LA-PrEP is likely to require reduced pricing and/or risk-prioritized rollout to be cost-effective in ESA.