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.
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.
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.
LA-PrEP is likely to require reduced pricing and/or risk-prioritized rollout to be cost-effective in ESA.
There has been significant progress in the rollout of oral pre-exposure prophylaxis (PrEP) for the prevention of HIV. The introduction of long-acting prevention methods holds the potential to improve HIV prevention uptake and use, however, presents unique complexities regarding HIV diagnosis and potential for resistance. Quantifying and understanding the scenarios within which seroconversions occur may help to inform approaches to identifying acute HIV in programmes delivering PrEP at scale.
This paper documents ctra series of seroconversions within a large implementation study conducted in eight Department of Health facilities and four linked mobile clinics in four areas of South Africa. Using routinely collected data, we conducted a descriptive analysis of clients who seroconverted after initiating oral PrEP and determined the distribution of time from oral PrEP initiation to seroconversion as well as the proportion of days covered by oral PrEP. A seroconversion was defined as any HIV-positive diagnosis after initiation of PrEP. Time to seroconversion was calculated as the number of days between the first PrEP initiation and the date of HIV diagnosis. The proportion of days covered by PrEP was calculated as the number of days of PrEP prescribed over the number of days between PrEP initiation and HIV seroconversion. We conducted a logistic regression to determine factors associated with seroconversion.
Of the 11,882 clients initiated on PrEP between January 2019 and October 2022 who attended at least one follow-up visit, 112 (0.9%) seroconverted after PrEP initiation. Among those who seroconverted, the median proportion of days covered by PrEP between initiation and seroconversion was 33%. In the period between PrEP initiation and seroconversion, almost all (n = 93, 83.0%) had not used PrEP consistently, with only 19 (17.0%) having consistent PrEP use, all of whom were identified at the 1-month follow-up visit and were likely missed acute acquisitions. Younger age and geographical area were associated with seroconversion.
This study reports a low number of seroconversions among a large cohort of PrEP users in a real-world implementation study, the majority of which occurred among clients who had interrupted or discontinued PrEP use.
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