Designing for access: implementation determinants of harm reduction vending machines in veterans supportive housing

Abstract Background Harm reduction vending machines (HRVMs) are an emerging strategy to provide convenient, low-threshold access to harm reduction and other health-related supplies, yet evidence and practical guidance on implementation, particularly in supportive housing and for Veterans, remain limited. We examined implementation determinants and generated participant-informed recommendations to optimize HRVM implementation in permanent supportive housing for formerly homeless Veterans. Methods We conducted a qualitative study in six permanent supportive housing buildings for formerly homeless Veterans in the San Francisco Bay Area. Between August and December 2024, we purposively sampled Veteran residents and on-site staff and conducted semi-structured interviews. Interviews were audio-recorded, transcribed, and analyzed using inductive thematic analysis with iterative codebook development and consensus discussion to develop implementation domains. We then conducted an implementation-focused synthesis to develop participant-informed recommendations and an implementation conceptual model. Results A total of 60 participants completed interviews, including 44 Veterans and 16 supportive housing staff. We identified four implementation domains related to HRVM design (balancing information accessibility and product visibility with privacy), maintenance/operations (ensuring access and reliable stocking), program awareness (word-of-mouth sharing, staff buy-in, and clear signage), and program expansion (Veteran-prioritized inventory additions and expansion to additional clinical and community locations). Participants also described cross-cutting challenges related to planning/installation and technical, physical, and language access, including fragile access cards, difficulty reaching the retrieval bin for some residents, and the need for multilingual materials. These domains informed an implementation model to guide HRVM implementation in supportive housing. Conclusions HRVMs in permanent supportive housing were perceived as a feasible and acceptable approach to expand low-barrier access to harm reduction and health-related supplies. Implementation design and execution, including attention to privacy, operational reliability, and accessibility, may influence whether HRVMs become trusted and routinely used resources. Programs should prioritize user-centered design and co-development with Veteran residents and staff, dependable stocking and maintenance workflows, integrated awareness-building and offering sign-ups within routine housing processes, and accessibility features including durable access options, waist-level retrieval, and multilingual materials.