Implementing HIV screening and prevention in low-barrier Office-Based Opioid Treatment (OBOT) programs to end the HIV epidemic - PROJECT SUMMARY/ABSTRACT To end the HIV epidemic (EHE), the United States aims to reduce HIV incidence by 90% by 2030. Achieving elimination of HIV will require increased efforts to screen, treat and prevent HIV among people who use drugs (PWUD). Recommended HIV prevention strategies for PWUD include use of medications for opioid use disorder (MOUD) as well as delivery of pre-exposure prophylaxis (PrEP). Nationally and locally, efforts to introduce PrEP among PWUD are suboptimal. Yet, our research suggests that PWUD are receptive to newer injectable formulations of PrEP, and the recent emergence of a twice-yearly subcutaneous formulation of PrEP (Lenacapravir) is a major “game-changer”. The landscape of treatment for substance use disorders is also evolving. Office-based opioid treatment (OBOT) programs that offer “low-barrier” MOUD like buprenorphine (including injectable formulations) with other primary care are becoming more widespread and polysubstance use (particularly co-use of opioids and methamphetamine) among those seeking treatment is now the norm. The focus in these programs is retention and meeting patients’ goals for treatment, which may mean reduction in use or safer use but not abstinence. In this context, it is imperative to offer screening/prevention for HIV. Evidence suggests integration of HIV testing and PrEP with OBOT programs is feasible yet in practice such care is not widely implemented. We propose research to improve the HIV screening and treatment cascade among patients cared for in four primary care-integrated, or co-located, OBOT programs offering MOUD at Harborview Medical Center. In Aim #1, we will conduct a convergent parallel mixed methods assessment to characterize the HIV testing and prevention cascade, assess preferences for PrEP modalities and other health services among persons receiving treatment in MOUD programs, and assess multi-level barriers and facilitators of service delivery. In Aim #2, we will develop, implement and evaluate implementation strategies serially in each clinic working collaboratively with clinic staff. This work will be grounded in the Information-Motivation-Behavioral Skills (IMB) and Consolidated Framework for Implementation Research (CFIR) frameworks. Reach, Effectiveness, Adoption, Implementation, and Maintenance (RE-AIM) will be used to evaluate the implementation strategies in all four clinics (N~340) in a pre-post study. The primary effectiveness outcomes are: 1) HIV screening and 2) PrEP prescribed. This proposal has the potential to “bend the curve” in HIV prevention in King County, Washington, which is one of the U.S. counties with the highest number of new HIV diagnoses. Furthermore, it will create a blueprint for other counties, thus contributing to the national EHE efforts. This research proposed is timely and novel as it coincides with the introduction of highly effective, long-acting injectable (LAI) formulations which can shift the clinical paradigm.