Hepatitis C virus direct acting antiviral (DAA) treatment success and its impact on transmission dynamics in HIV/HCV co-infected MSM

Globally, 3-4 million hepatitis C virus (HCV) infections occur annually with injecting drug users (IDUs)and HIV positive men-who-have-sex-with-men (MSM) at highest risk. While spontaneous clearanceoccurs, the majority develops chronic infection with risk for cirrhosis, end-stage liver disease andhepatocellular carcinoma. In MSM, HCV transmission routes are unclear but concurrent IDU, coinfectionwith HIV and high-risk sexual practices are probable determinants. In this new era of directacting antivirals (DAA), clearance rates of treated HCV infection are >90%. However, successfultreatment does not preclude patients from persisting their risk behaviour leading to reinfection,which reduces the long-term DAA-attributable impact on the dynamics of HCV spread at populationlevel. Therefore the aim of this study is to investigate transmission characteristics of HCV at (re)infection in Belgian MSM treated with or starting DAA. We will collate clinical, demographic, riskbehaviour,epidemiological and viral data from different study populations in Belgium. Phylogenetictransmission clusters and predictors for treatment success, resistance and reinfection will bedetermined and used to help construct innovative mathematical transmission models allowing topredict the long-term efficacy of DAA and its impact on disease dynamics. The resultingepidemiological HCV models will have direct relevance to clinicians and policy-makers in the field ofpublic health and HCV management.