Funding Information: This research and Kasper Thorhauge Christensen was funded by grants from the Fonds Wetenschappelijk Onderzoek Vlaanderen (FWO) (G069214, G0B2317N and 1S38819N). Lize Cuypers acknowledges FWO travel grant for a research visit at the University of Oxford (V431117N). Core funding to the Wellcome Centre for Human Genetics was provided by the Wellcome Trust (award 203141/Z/16/Z). The authors acknowledge the STOP-HCV consortium that was funded by a grant from the Medical Research Council, United Kingdom (MR/K01532X/1). Publisher Copyright: © 2023 by the authors. ; The hepatitis C virus (HCV) epidemic in Western countries is primarily perpetuated by the sub-populations of men who have sex with men (MSM) and people who inject drugs (PWID). Understanding the dynamics of transmission in these communities is crucial for removing the remaining hurdles towards HCV elimination. We sequenced 269 annotated HCV plasma samples using probe enrichment and next-generation sequencing, obtaining 224 open reading frames of HCV (OR497849-OR498072). Maximum likelihood phylogenies were generated on the four most prevalent subtypes in this study (HCV1a, 1b, 3a, 4d) with a subsequent transmission cluster analysis. The highest rate of clustering was observed for HCV4d samples (13/17 (76.47%)). The second highest rate of clustering was observed in HCV1a samples (42/78 (53.85%)) with significant association with HIV-positive MSM. HCV1b and HCV3a had very low rates of clustering (2/83 (2.41%) and (0/29)). The spread of the prevalent subtype HCV1b appears to have been largely curtailed, and we demonstrate the onwards transmission of HCV1a and HCV4d in the HIV-positive MSM population across municipal borders. More systematic data collection and sequencing is needed to allow a better understanding of the HCV transmission among the community of PWID and overcome the remaining barriers for HCV elimination in Belgium. ; publishersversion ; published