Risk-stratified willingness to take PrEP for people who inject drugs: prioritizing sex work, MSM and syringe sharing, in southern syringe services programs.

People who inject drugs (PWID) in the Southern United States face elevated HIV risk due to limited testing, constrained PrEP access and structural barriers to harm reduction. Within syringe service programs (SSPs), universal PrEP delivery may be inefficient. Key subgroups - individuals engaged in sex work, men who have sex with men (MSM) and people sharing syringes - have distinct risk profiles, awareness, and motivation that influence PrEP uptake. This study identifies high-yield groups for risk-stratified PrEP delivery in SSPs. We conducted a cross-sectional survey of 685 PWID attending SSPs in Tennessee. Measures included demographics, drug use, sexual risk, PrEP awareness, willingness to initiate PrEP and objective HIV risk using the ARCH tool. Multivariate logistic regression identified predictors of willingness. Overall, 63.1% reported willingness to use PrEP. Willingness was highest among those engaged in sex work (80-81%; adjusted OR 2.5-3.3, p < 0.05). MSM had greater awareness but no higher adjusted willingness. Syringe sharers had the highest objective risk yet lower awareness and willingness, indicating a high-risk but harder-to-engage group. These findings highlight the potential value of tailoring PrEP promotion strategies within SSPs. While individuals engaged in sex work may be well positioned for rapid PrEP initiation, additional efforts may be needed to improve PrEP uptake among those who report syringe sharing.