Epidemiological impact and cost-effectiveness of providing long-acting pre-exposure prophylaxis to injectable contraceptive users for HIV prevention in South Africa: a modelling study.

Introduction: Although pre-exposure prophylaxis (PrEP.) is an efficacious HIV prevention strategy, its preventive benefit has not been shown among young women in sub-Saharan Africa, likely due to non-adherence. Adherence may be improved with the use of injectable long-acting PrEP methods currently being developed. We hypothesize that providing long-acting PrEP to women using injectable contraceptives, the most frequently used contraceptive method in South Africa, could improve adherence to PrEP, result in a reduction of new HIV infections, and be a relatively easy-to-reach target population. In this modelling study, we assessed the epidemiological impact and cost-effectiveness of providing long-acting PrEP to injectable contraceptive users in Limpopo, South Africa.

Methods: We developed a deterministic mathematical model calibrated to the HIV epidemic in Limpopo. Long-acting PrEP was provided to 50% of HIV negative injectable contraceptive users in 2018 and scaled-up over two years. We estimated the number of HIV infections that could be averted by 2030 and the drug price of long-acting PrEP for which this intervention would be cost-effective over a time horizon of 40 years, from a healthcare payer perspective. In the base-case scenario we assumed long-acting PrEP is 75% effective in preventing HIV infections and 85% of infected individuals are on antiretroviral drug therapy (ART) by 2030. In sensitivity analyses we adjusted PrEP effectiveness and ART coverage. Costs between $519 and $1119 per disability-adjusted life-year (DALY) averted were considered potentially cost-effective, and <$519 as cost-effective.

Results: Without long-acting injectable PrEP, 224,000 (interquartile range 176,000 to 271,000) new infections will occur by 2030; use of long-acting injectable PrEP could prevent 21,000 (17,000 to 26,000) or 9.8% (8.9% to 10.6%) new HIV infections by 2030 (including 6000 (4000 to 7000) in men). Long-acting PrEP would prevent 34,000 (29,000 to 39,000) or 12,000 (8000 to 15,000) at 75% and 95% ART coverage by 2030 respectively. To be considered potentially cost-effective the annual long-acting PrEP drug price should be <$16, and/or ART coverage remains at <85% in 2030.

Conclusions: Providing long-acting PrEP to injectable contraceptive users in Limpopo is only potentially cost-effective when long-acting PrEP drug prices are low. If low prices are not feasible, providing long-acting PrEP only to women at high risk of HIV infection will become important.