Injection Drug Use

The study will use social media to recruit a diverse sample of people who self-report injecting drugs, assessing the feasibility of online assessments and participants' ability to perform at-home self-administered HIV testing. Participants will complete online questionnaires at baseline and will be mailed HIV testing kits that they will self-administer and mail to a central laboratory. Investigators will track completion of questionnaires and whether at-home self-administered HIV tests were completed and sent to the laboratory.

This randomized clinical trial (RCT) evaluates whether metformin can reduce systemic inflammation and improve immune function in individuals with a history of injection drug use, with or without HIV. Participants will receive metformin or placebo and undergo immune system assessments, including vaccine response evaluations.

The goal of this study is to determine the feasibility and impact of delivering long-acting injectable cabotegravir HIV pre-exposure prophylaxis and suite of support services to adults who inject non-prescription drugs who are risk for HIV through known sexual risk.

The goal of this clinical trial is to learn whether a low-barrier treatment program can help people with hepatitis C virus (HCV) who are in jail start and complete treatment more easily. This study focuses on adults at the Rhode Island Department of Corrections who have active HCV and are awaiting trial. The study asks: * Can a simplified, low-barrier HCV treatment program work in a jail setting? * Do participants finish treatment and get cured using this approach? All participants will receive a 12-week course of the HCV medication sofosbuvir/velpatasvir (Epclusa). If they are released before completing treatment, they will take the remaining doses with them. Community Health Workers (CHWs) will help support participants after release, including reminding them to take medications and helping them get follow-up lab work. Researchers will measure: * Whether participants are cured of HCV * Whether the treatment approach is easy to use (feasible), acceptable, and followed correctly (fidelity) * Whether the program could be used in other jails or expanded in the future This study may help bring HCV treatment to more people in jail, reduce community spread of the virus, and support national goals to eliminate HCV.