Abstract
People who inject drugs (PWID) face significant barriers to HIV care, yet long-acting injectable antiretroviral therapy (LAI-ART) offers a promising alternative to daily oral regimens. Syringe service programs (SSPs) may be uniquely positioned to deliver LAI-ART, but implementation in these settings remains underexplored. This convergent mixed-methods study examined the acceptability and feasibility of LAI-ART across three Florida SSPs by identifying multilevel barriers and facilitators. Quantitative data from 203 SSP clients living with HIV showed strong interest in LAI-ART, especially among younger participants and those who recently used methamphetamine, though many were excluded by viral suppression requirements. Qualitative interviews with SSP staff (n = 7), guided by the Consolidated Framework for Implementation Research (CFIR), revealed operational challenges, medication storage, staffing, cost, and lack of planning, alongside facilitators such as team collaboration, peer outreach, and alignment with harm reduction values. Findings suggest that while LAI-ART is acceptable to clients and staff, successful integration will require tailored strategies like expanded eligibility, mobile delivery, and sustainable reimbursement models. This study highlights the potential for SSPs to expand HIV treatment access for PWID and provides implementation guidance to support equitable scale-up.