Evaluating the Implementation and Impact of Harm Reduction Vending Machines in Veterans Supportive Housing Settings: A Mixed-Methods Study Protocol

Background: Lack of access to sterile supplies among people who use drugs contributes to increased rates of infectious disease transmission, including human immunodeficiency virus, hepatitis C virus, and sexually transmitted infections. People residing in California, United States Veterans, and those experiencing homelessness are disproportionately impacted. Syringe services programs (SSPs) are vital to reducing these harms, but access may be limited by hours of operation, geographic barriers, need for in-person interaction, and stigma. Harm reduction vending machines (HRVMs) which often dispense sterile syringes and condoms are an evidence-based strategy to increase access; however, no studies have evaluated implementation or impacts among these populations. This mixed-methods study aims to evaluate the first HRVM program designed for Veterans who experienced homelessness and reside in California supportive housing buildings. Methods: We will recruit 40 Veteran residents and 20 staff (Veterans Affairs [VA] and housing staff) at six housing buildings with a collocated HRVM. Participants will provide informed consent, complete a standardized electronic questionnaire, semi-structured qualitative interview, and be compensated via Visa gift cards ($90 for Veterans; $60 for staff). Interview transcripts will be analyzed thematically using inductive coding. Program-level data will be collected from enrollment logs, facility records, and vending machine software to evaluate reach, effectiveness, adoption, implementation, and maintenance (RE-AIM). Discussion: Findings will provide essential evidence on how HRVMs may reduce longstanding access barriers and expand delivery of life-saving harm reduction supplies to underserved Veterans. This study is the first to evaluate HRVMs in Veterans supportive housing and among a population disproportionately affected by substance use, stigma, and homelessness. Results may inform the expansion of community-based and VA SSPs nationwide. Study strengths include a theory-informed design, real-world implementation data, and attention to user and staff experiences. Limitations include reliance on self-report data, lack of a control group, and limited generalizability beyond Veterans. Future research may examine long-term health outcomes, cost-effectiveness, and feasibility of HRVMs scaled up in diverse settings. Findings from this study may guide policymakers and public health practitioners in integrating HRVMs into broader harm reduction strategies to prevent overdose, infections, and other adverse outcomes.