Salazar-Vizcaya L, et al. - Researchers aimed at classifying HCV infections in HIV-positive men-who-have-sex-with-men (MSM) as either domestically or internationally acquired, and at estimating how this classification changed over time via sequencing HCV subtype 1a (the most frequent subtype among MSM) genomes from 99 persons enrolled in the Swiss-HIV-Cohort-Study (SHCS) and diagnosed with replicating HCV infections between 1999 and 2016. Sixty-six of these sequences were from MSM. Findings revealed 50% to 80% of HCV transmissions as domestic depending on the classification criterion. The fraction attributable to the domestic transmission was 54% between 2000 and 2007 and this increased to 85% between 2008 and 2016. In the epidemic, international and domestic transmission are noted to play major roles. Local transmission has established as the main source of infections with the persistence of international transmission.