Effectiveness of treating recently acquired hepatitis C virus infection

Hepatitis C virus infection affects an estimated 180 million people globally. Individuals at high-risk of acquiring infection include people who inject drugs, particularly in high-income settings where medically-acquired or perinatal hepatitis C infection is now rare. While treatment can be curative, detecting recently acquired infection, linking individuals to care, and initiating therapy all remain challenges. This thesis aims to determine whether treatment of recently acquired hepatitis C infection is worthwhile given the complexities and toxicities of antiviral therapy, particularly among people who inject drugs, and recent improvements in treatment of chronic hepatitis C infection. It first explores the effectiveness of antiviral therapy with pegylated-interferon for recent hepatitis C and determines that host IFNL4 genotype and duration of infection, among other factors, can be used to predict cure. It then evaluates how treatment affects quality of life and social functioning, finding that medication side effects have a short-term adverse impact on individuals. Social stability is an independent predictor of treatment uptake and cure. Providing social supports to individuals before treatment could therefore become an important intervention, regardless of which medications are available. Finally, the thesis presents the first, prospective long-term evaluation after acute infection and treatment. Hepatitis C reinfection incidence was low and injecting-risk taking declined over time, indicating that the benefits of early cure are sustained. Recent hepatitis C treatment is shown to be a feasible intervention where incident hepatitis C infection is identified, potentially avoiding long-term complications associated with chronic infection. With the evolution toward simpler, more effective, but more costly interferon-free therapy for chronic hepatitis C, future population health research needs to evaluate the cost-effectiveness of recent HCV treatment and any effect of treatment on preventing transmission. Access to interferon-free treatment should be prioritised for this marginalised population in order to maximise treatment uptake.