This project will assess the impact of an HIV screening, partner notification, and immediate ART intervention in 1,500 adult patients aged 18-39 years who seek care for urgent symptoms at primary care facilities. The intervention will: (1) identify eligible adults meeting AHI screening criteria and test them for both acute and prevalent HIV; (2) link all newly diagnosed patients to HIV care with immediate ART; and (3) offer assisted partner notification services (aPS) to all cases detected, identifying local sexual networks. The research team will model the potential impact of this multi-component intervention on the Kenyan HIV epidemic, estimating incremental costs per HIV infection averted, death averted, and DALY averted; and conduct qualitative in-depth interviews with up to 60 newly diagnosed prevalent and AHI patients and seronegative partners in discordant relationships to gain insights into programme uptake, including barriers and facilitators to ART or PrEP uptake and adherence. The study will use a modified step wedge design to evaluate the yield of the screening intervention at 2 public and 4 private facilities in Kenya, before and after intervention delivery. Results will contribute to the development of improved strategies for AHI detection, use of aPS for partners of AHI patients, and use of ART and PrEP for HIV prevention.