PROJECT SUMMARY Unhealthy alcohol use is common among men who have sex with men (MSM). Unhealthy alcohol use is a spectrum from risky/hazardous drinking to alcohol use disorder. For MSM, unhealthy alcohol use may reduce PrEP persistence and adherence, which are critical for HIV prevention. Reducing unhealthy alcohol use may improve PrEP outcomes. The brief alcohol intervention (BAI), which draws on Motivational Interviewing and Cognitive Behavioral Therapy, increases viral suppression among people living with HIV on antiretroviral therapy. This effect is mediated through increased adherence. The BAI may have a similar effect on PrEP outcomes among MSM with unhealthy alcohol use. We propose an effectiveness-implementation type 1 hybrid randomized controlled trial (RCT) to compare the BAI to standard of care among MSM with unhealthy alcohol use initiating or re-initiating PrEP in Vietnam. We hypothesize that the BAI will improve a) PrEP persistence, b) PrEP adherence, and c) risk-aligned PrEP use (PrEP use consistent with current risk, including event-driven PrEP). Our specific aims are to: 1) Assess effectiveness of the BAI for increasing PrEP persistence and adherence among MSM in Vietnam; 2) Assess the impact of the BAI on alcohol use among MSM; 3) Estimate the cost-effectiveness, feasibility, and acceptability of scaling up the BAI in PrEP clinics throughout Vietnam. The trial and intervention will be conducted at the Hanoi Medical University PrEP clinic for MSM Vietnam. Evaluation visits will be conducted at UNC Project-Vietnam. Eligible participants will include MSM (n=506) presenting to the PrEP clinic for PrEP initiation or re-initiation after 6 months without PrEP. The participants must also screen positive for unhealthy alcohol use with an AUDIT-C score ≥ 4. After baseline evaluations, participants will be randomized to either standard of care or the BAI, which comprises two in-person and two telephone visits. Each participant will be followed quarterly with interviews, including use of timeline followback to elicit PrEP use, alcohol use, and sexual behavior, and tests for HIV infection, gonorrhea, chlamydial infection, and syphilis. Alcohol use and PrEP adherence will also be assessed with biomarkers. The primary effectiveness outcome is PrEP persistence at 6 and 12 months. Secondary outcomes include PrEP adherence, assessed by self-report, pharmacy records, and validated bioassays; risk-aligned PrEP use; and alcohol outcomes (heavy drinking days (binge drinking), defined as the number of days with ≥5 drinks per occasion; number of drinking days; and drinks per drinking day; and phosphatidylethanol level). The primary implementation outcomes are the incremental cost-effectiveness ratio, expressed as the incremental cost per quality-adjusted life-year gained, and feasibility and acceptability. If successful, this study will be set to ensure rapid scale up of an intervention to improve the lives of MSM by reducing unhealthy alcohol use and...