Although there is ongoing debate over the need for substantial increases in pre-exposure prophylaxis (PrEP) use when antiretroviral treatment confers the dual benefits of reducing HIV-related morbidity and mortality and the risk of HIV transmission, no studies to date have quantified the potential added benefits of PrEP use and changes in its efficiency in the context of high treatment engagement across multiple US subpopulations. We used a previously published agent-based model to simulate HIV transmission in a dynamic network of Black/African American and White men who have sex with men (MSM) in Atlanta, Georgia (2015-2024) to understand how reductions in HIV incidence attributable to varying levels of PrEP use change when United Nations Joint Programme on HIV/AIDS (UNAIDS) "90-90-90" goals for HIV treatment are achieved and maintained. Even at achievement of "90-90-90" goals, 75% PrEP coverage further reduced incidence by 67.9% and 74.2% to 1.53 [simulation interval (SI): 1.39-1.70] and 0.355 (SI: 0.316-0.391) per 100 person-years for Black/African American and White MSM, respectively, compared with the same scenario with no PrEP use. Increasing PrEP coverage from 15% to 75% under "90-90-90" goals only increased the number of person-years of PrEP use per infection averted by 8.1% and 10.5% to 26.7 (SI: 25.6-28.0) and 73.3 (SI: 70.6-75.7) among Black/African American MSM and White MSM, respectively. Even with high treatment engagement, substantial expansion of PrEP use contributes to meaningful decreases in HIV incidence among MSM with minimal changes in efficiency.
Keywords: agent-based modeling; combination HIV prevention; health disparities.