This study builds upon an ongoing NIH-funded randomized controlled trial (R01DA053325) evaluating a Partner Navigation Intervention to increase hepatitis C virus (HCV) treatment initiation among young adult people who inject drugs (PWID) and their injecting partners in San Francisco. The proposed research includes secondary analyses of existing trial data, additional survey measures, qualitative interviews, and a pilot intervention adaptation.

The study has two primary objectives. First, it examines how racialized discrimination (structural, interpersonal, and internalized) affects HCV treatment initiation and dyadic partner support processes within injecting partnerships. Second, it evaluates whether a brief, adapted "booster" partner navigation session delivered at HCV treatment completion can improve engagement in ongoing healthcare.

Participants include adults (≥18 years) who inject drugs and have been diagnosed with HCV, along with their primary injecting partners. Study activities include longitudinal surveys, qualitative interviews with a subset of participants, and a pilot intervention session with follow-up evaluation.

This research addresses critical gaps in understanding how social relationships and structural inequities influence healthcare engagement among PWID. Findings will inform culturally responsive adaptations to dyadic interventions and improve continuity of care in a population disproportionately affected by HCV and systemic barriers to healthcare.

Inclusion criteria:

For index participants:

• 18 years of age or older at enrollment
• History of injecting drug use
• Completed HCV treatment within the past 3 months
• Report a primary injecting partner willing to participate
• Willing and able to provide informed consent
• English or Spanish speaking

For primary injecting partners:

• Primary injecting partner of an enrolled index participant:
• 18 years of age or older at enrollment
• Willing and able to provide informed consent
• English or Spanish speaking
• has context menu

Exclusion criteria:

For both index participants and injecting partners:

• Unable to provide informed consent due to cognitive impairment or acute intoxication at the time of enrollment
• Previously participated in this study in any capacity

This is a pilot/feasibility study with a small target enrollment of 15-25 dyads (30-50 individuals). Given the small sample size and the sensitive nature of the study population (PWID, involving disclosure of illegal drug use behaviors and medical history), individual-level data sharing poses meaningful re-identification risk even after de-identification. Aggregate de-identified findings will be reported in peer-reviewed publication and on ClinicalTrials.gov per standard reporting requirements.