PROJECT SUMMARY The objective of the proposed research is to improve the response to incident HIV infection by engaging the networks of Black men who have sex with men (BMSM) and transgender women (TGW) through a combination of Partner Services, social network recruitment, and HIV genetic cluster detection. Despite marked advances in HIV treatment and prevention, HIV incidence has not substantially declined among BMSM/TGW in the Southern United States (US), highlighting the need for innovative methods to detect and respond to ongoing HIV transmission. While Partner Services can be highly effective, case finding remains limited even for persons diagnosed soon after HIV acquisition (acute or recent infections). Partner Services can also be limited in investigations across jurisdictional boundaries and in rural areas. We hypothesize that leveraging the social networks (social contacts rather than only drug sharing or sexual partners) of networks with recent HIV transmission will lead to improved engagement in HIV services (prevention or care). However, such strategies must be responsive to the barriers and facilitators to engagement in these services including a better understanding of social support networks. This project involves a multidisciplinary team including robust public health partnerships and active community engagement to address HIV prevention needs and build on existing resources. We will develop and implement an enhanced social network strategy (eSNS) for networks of BMSM/TGW with new HIV diagnoses, including acute incident infection, in the high-burden Charlotte region (Mecklenburg County, North Carolina), situated on the border of South Carolina. Both areas are priority regions in the Ending the Epidemic (EHE) initiative. In the eSNS intervention, new diagnoses will receive rapid response Partner Services for elicitation of social and sexual contacts; selected contacts will be recruited and coached to recruit their peers to engage in HIV services. Aim 1 will employ regional genetic and contact network analysis of incident and prevalent HIV in North and South Carolina, to evaluate important connections (bridging) between states and between urban and rural areas. This granular data (contact, spatial, genetic) will expand epidemiological understanding of the epidemic to inform development of the eSNS and enhance local EHE strategies. To further inform eSNS development, Aim 2 will use a mixed methods approach to examine the barriers and facilitators of engaging BMSM/TGW members of networks with recent HIV transmission. Aim 3 will then evaluate the eSNS with effectiveness and implementation outcomes. Effectiveness outcomes (increase in testing, pre-exposure prophylaxis referral, and HIV care engagement) will be evaluated with regression point displacement design comparing outcomes pre/post intervention in Charlotte and in comparison, with the Raleigh region receiving standard of care partner services. Overall, the results of this project...