Long-acting injectable PrEP can substantially reduce HIV incidence in Los Angeles County: A simulation study

Abstract

Background: Although oral pre-exposure prophylaxis (PrEP) has been instrumental in decreasing HIV incidence, its daily dosing regimen poses adherence challenges. Using an agent-based network model informed by empirical data, we simulate the impact of introducing long-acting injectable (LAI) PrEP among young Black men who have sex with men (YBMSM) in Los Angeles County, a group disproportionately affected by HIV.

Setting: Computer simulations using an agent-based network model (ABNM).

Methods: We modeled HIV transmission among YBMSM over 10 years under scenarios varying the proportion of PrEP users opting for LAI instead of oral medications and adherence levels to LAI retention. The model was calibrated with empirical data and included dynamic sexual networks, HIV progression, and biomedical interventions.

Results: Modeling showed that LAI PrEP substantially reduced HIV incidence and prevalence over 10 years compared to oral PrEP alone. Scenarios with LAI retention (i.e., continued use across bimonthly dosing cycles) rates of 60% or higher resulted in reductions comparable to or exceeding those achieved by oral PrEP, with up to a 45% decrease in HIV incidence observed when all PrEP users switched to LAI and retention reached 85%.

Conclusion: Long-acting injectable PrEP offers significant potential to advance HIV prevention efforts among YBMSM by addressing adherence challenges inherent to oral PrEP. Integrating LAI into public health initiatives may yield substantial reductions in HIV incidence, contributing to ending the HIV epidemic among this high-priority population.

Keywords: Agent-based network model; Computer simulation; HIV; Long-acting injectable; Pre-Exposure Prophylaxis; Sexual and Gender Minorities.