Impact and Equality of Expanding Pre-Exposure Prophylaxis (PrEP) for Men who have Sex with Men in Los Angeles County

Background Racial and ethnic minority men who have sex with men (MSM) are disproportionately affected by HIV/AIDS in Los Angeles County (LAC), an important epicenter in the battle to end HIV. Our objective is to examine tradeoffs between effectiveness and equality of PrEP allocation strategies among different racial and ethnic groups of MSM in LAC. Methods We developed a microsimulation model of HIV among MSM in LAC using county epidemic surveillance and survey data to capture demographic trends and subgroup-specific partnership patterns, disease progression, patterns of PrEP use, and patterns for viral suppression. We simulated interventions where an additional 3000, 6000, or 9000 PrEP prescriptions are provided annually in addition to current levels, following different allocation scenarios to each racial/ethnic group (Black, Hispanic, or White). We limit analysis to MSM, who bear the majority of HIV/AIDS burden in LAC. We do not consider transmission via injection drug use or mother-to-child transmission, nor do we capture individual network transmission effects. We assume no improvements in the prevention-diagnosis-treatment cascade besides increased PrEP use. Findings We estimated cumulative infections averted and measures of equality, after 15 years (2021-2035), relative to base case (no intervention). Of the policies evaluated, targeting PrEP preferentially to Black individuals would result in the largest reductions in incidence and disparities. This outcome was robust to different partnership preference assumptions, though the magnitude of impact differs. Interpretation We find there is little trade-off between effectiveness and equality of outcome when choosing groups to target for PrEP in LAC -- by focusing on MSM with the highest HIV incidence (Black), we can reduce both overall infections and racial/ethnic disparities.