Do Geographic Barriers and Community Vulnerability Impact PrEP Use Among Transgender Latinas in the US South? Findings from the ChiCAS Study.

Transgender (trans) Latinas in the United States face disproportionately higher HIV rates and persistently low use of pre-exposure prophylaxis (PrEP) despite awareness. While geographic access to PrEP has been identified as a barrier in other populations, little is known about how spatial access and community-level vulnerability shape PrEP use among trans Latinas in the US South. Using data from the randomized intervention-waitlist control trial of ChiCAS (N = 144), we examined (1) proximity to Spanish-language PrEP providers, (2) neighborhood vulnerability using the Social Vulnerability Index (SVI), Structural Racism Effect Index (SREI), and the Index of Concentration at the Extremes (ICE), and (3) their associations with PrEP use among trans Latinas at baseline and 6-month follow-up. Multivariable models tested whether baseline contextual factors modified intervention effects. Overall, 15.3% of participants lived in a PrEP desert (≥ 30-minute drive to a Spanish-language PrEP provider). Participants resided in highly vulnerable neighborhoods. Neither PrEP desert status nor community-level vulnerability indices were significantly associated with PrEP use at baseline or follow-up. However, SREI significantly moderated intervention effects (interaction adjusted odds ratio [aOR] = 4.55; 95% confidence interval [CI]:1.08-19.2), with greater intervention impact in areas of higher structural vulnerability. Findings suggest that structural racism, not geographic proximity, more strongly shape PrEP access and use among trans Latinas. Culturally responsive, bilingual interventions like ChiCAS may be particularly effective in structurally disadvantaged settings. Future efforts must address structural and social determinants alongside spatial access to achieve PrEP equity.