Informing, Updating and Adapting an Existing Evidence-Based Social Network Alteration Intervention for HIV Transmission Elimination - Project Summary Advancements in biomedical strategies have the potential to prevent all new HIV transmissions in the US. Despite having the tools needed to end the HIV epidemic (EHE), HIV continues to disproportionately affect certain EHE priority populations. These groups have a heavy burden of HIV, experience suboptimal HIV prevention and care outcomes, and have a heavy burden of sexually transmitted infections (STIs). They also face structural barriers to HIV transmission elimination, such as challenges related to income, housing and substance use. In response, this EHE implementation science project aims to work with community-based partners to co-create a scalable type 4 social network alteration intervention capable of surmounting these structural barriers by updating and adapting the evidence-based WiLLOW program. Adaptation is a critical concept in Implementation Science and enhances the relevance, acceptability, feasibility, and cultural sensitivity of interventions. We will collaborate with our community-partners and federally qualified health center (FQHC) providers to implement study activities. The first aim of the project is to identify key network-driven determinants and features amenable to type 4 social network alteration intervention by structure (i.e., centrality measures including constraint, betweenness, bridging) and function (e.g., type of support: informational, social/emotional, material). The second aim is to conduct a series of 6 workshops involving key stakeholders (e.g., community members, CBO staff, CCHE providers) using human-centered design (HCD) methods (e.g., network mapping, journey mapping, card sorting; situated within the Discover-Design-Build-Test framework) to inform how to update and adapt WiLLOW. Using HCD will allow us to operationalize adaptation as a process of thoughtful and deliberate alteration of the design and delivery of WiLLOW with the goal to improve fit of the intervention with the needs, circumstances, and culture of end users, as informed by the community, and with that, strengthen potential effectiveness. In follow-up to the work for this project, the MPI’s will develop and submit an R34 proposal to evaluate the effectiveness and implementation of an adapted type 4 social network alteration intervention in an effectiveness-implementation hybrid study. In summary, this R21 project will help to address three EHE pillars (Diagnose, Prevent, Treat), and help to abate long-standing health challenges among an EHE priority population.