Who is accessing PrEP in Mexico? Profiling users and identifying the unreached among high-risk MSM

Despite preexposure prophylaxis (PrEP) expansion in Mexico, concerns remain about equitable access. Using counterfactual prediction and propensity score matching, we compared a nonprobability sample of PrEP users with high-risk men who have sex with men (MSM) from a national survey. Findings indicate that the program may miss up to 60% of high-risk MSM based on their profile and location, with younger and less educated men particularly unlikely to access PrEP, highlighting persistent gaps in the current program.