The Clinician Referral arm will serve as an "active control" and baseline standard of care. All individuals who test positive for HCV antibodies or are identified with untreated, active HCV will be informed of their result and receive the following information from their clinical care teams in the ED: (a) explanation of process and rationale for follow-up RNA testing; (b) delivery of simple posttest counseling (e.g., risk for liver disease, risks of transmission); and (c) provision of a list of insurance enrollment resources, as needed, along with (d) a list of HCV treatment providers and their contact information as provided in aftercare instructions. For new HCV diagnoses, patients will be instructed to access their electronic patient portal (MyChart) for their RNA test results or to call a designated results line. Post-testing counseling messages and follow-up instructions will be included on the patient discharge papers.

The Linkage Navigation arm will consist of an additional service layered onto clinician referral and will incorporate protocols from Antiretroviral Treatment and Access Studies (ARTAS). Individuals randomized to this intervention will be contacted by a linkage navigator either during the ED visit (if during business hours) or the following business day (if during non-business hours). If the navigator does not contact the patient at the time of ED visit, they will offer to meet with the patient in person or over the phone. For all individuals in this arm, a structured linkage navigation process will include motivational interviewing and (a) reiteration of posttest counseling messages, (b) assessment of the patient's needs for medical insurance and substance abuse treatment, c) assistance scheduling and/or rescheduling appointments for HCV treatment, and d) follow-up phone call after the first HCV treatment appointment and thereafter as needed up to 6 months after ED visit.

The Linkage Navigation arm will consist of an additional service layered onto clinician referral and will incorporate protocols from Antiretroviral Treatment and Access Studies (ARTAS), the most influential studies of HIV linkage-to-care to date.

The primary outcome will be the number of individuals with positive HCV RNA test who initiate HCV treatment within 6 months from the time of ED diagnosis (for new HCV diagnoses) or from time of ED visit (for those identified with untreated, active HCV). This will be verified by electronic medical record review.

Measured by indication of a completed visit with an HCV treatment provider among those identified with active HCV. This will be verified by electronic medical record review.

Measured by indication of a completed visit with a substance use treatment provider. This will be verified via electronic medical record review.