Presence, absence, and contingent engagement: mobilising care in the endgame of hepatitis C elimination.

BACKGROUND: In the 'endgame' of hepatitis C elimination, mobile and other decentralised care models instrumentalise point-of-care testing and direct-acting antivirals to innovate care pathways for underserved populations. While implementation science evidences their 'effectiveness', less is known about how these interventions work in practice and how their effects are produced in specific settings.

APPROACH: This ethnographic case study traced a mobile, nurse- and peer-led hepatitis C clinic operating adjacent to community-based correctional services sites across Melbourne, Australia. Fieldwork (2024-2025) comprised 200 h of observation and 19 interviews with staff, participants, and stakeholders. Informed by science and technology studies and the concept of evidence-making interventions, analysis examined how the intervention was assembled, adapted, and made to work.

ANALYSIS: The clinic supported high testing and treatment uptake by engaging participants opportunistically in everyday life. Its effects emerged not from design features alone (e.g., mobility, point-of-care testing), but through situated practices, including its inconspicuous presence, time-limited availability, and staff's relational work. Engagement was produced through interruption, timing, and trust, while care continuity relied on networks spanning secondary contacts, services, and fragile infrastructures. Hepatitis C care was enacted alongside - and sometimes secondary to - responses to broader social and material needs, positioning the intervention as a distributed, shifting assemblage rather than a bounded model of care.

CONCLUSION: This analysis challenges implementation science logics that model 'effectiveness' as stable and transferable. It underscores the situated and variable nature of care, highlighting opportunities to reconceptualise the boundaries of hepatitis C interventions.