Accelerating HIV prevention in high-risk prison environments - With 9,500 inmates and a 10.3% HIV prevalence, 75% of whom have a history of injecting drug use (IDU), including up to 1/3 within-prison, Kyrgyzstan's prisons are crucial for HIV control efforts. Previous interventions failed to increase OAT uptake, encountering significant barriers, including stigma and drug use stigma in prison. During the K01 study, our multidisciplinary Kyrgyz team co-developed HOPE (Help OAT Prison Engagement), a 6-week intervention tailored to the prison HIV high-risk environment. HOPE incorporates several evidence-informed elements, including a) HIV screening followed by HIV literacy session, b) assessing depressive and anxiety symptoms and positive mental health elements (e.g., quality of life, social support, and self-reported resilience), followed by mindfulness enhancement sessions, and c) addiction literacy and self-management. HOPE also increases self-efficacy through empowerment-based skills-building, including managing OAT stigma and conflict in a high-risk prison environment and resource utilization. Each of HOPE’s 12 thematic components comprises a mini-lecture, a group discussion, and group exercises practicing targeted skills. We plan to compare HOPE to an information-only control using a type 1, hybrid implementation trial to evaluate the effectiveness of HOPE for HIV prevention in prison, including uptake of OAT/SSP services, combined with exploration of implementation factors that may contribute to intervention effects and a future scale-up. We aim (1) to conduct a cluster randomized controlled trial of the HOPE intervention to determine its effectiveness for HIV prevention (i.e., OAT and SSP use) over 12 months. We will enroll 360 participants who have over 1 year remaining before release across 20 housing units (each HU has ~100 PIP) from four male prisons in Kyrgyzstan. Assessments will occur at baseline, 3, 6, 9, and 12 months. The primary outcome is OAT start; secondary outcomes include other HIV risk-reduction strategies like SSP use and engagement in HIV risk behaviors. Aim 2 is to conduct a combination of qualitative interviews and focus group discussions to examine implementation factors associated with the effectiveness of HOPE, its uptake and scale-up from the perspective of multi-level stakeholders. Aim 3: Use results from Aim 1 to conduct a cost-effectiveness analysis (CEA) of HOPE relative to the control for reducing HIV transmission and improving quality of life among PIP. This study is relevant to the US (and global) public health as findings will provide effectiveness, implementation and cost-effectiveness data for low-resource settings where PWID are concentrated in prison settings.