One of the World Health Organization's targets for the 2030 viral hepatitis elimination strategy is to reduce new hepatitis C (HCV) infections. In Athens, Greece, people who inject drugs (PWID) have a high HCV prevalence, with increasing trends since the 2000s. This analysis aims to assess primary HCV incidence among PWID during 2012-2020. Two community-based interventions were implemented in 2012-2013 and 2018-2020 with repeated serobehavioural surveys in each period. Participants enrolled in multiple surveys were identified through linkage. To assess trends in HCV transmission, three indicators were estimated: i) anti-HCV prevalence among "new" injectors (those injecting ≤2 years), ii) indirect HCV incidence among "new" injectors, assuming infection occurred at the midpoint between initiating injection and the first positive test, and iii) HCV incidence from repeat participants. There were 431 and 125 "new" injectors, respectively, in 2012-2013 and 2018-2020. Αnti-HCV prevalence [95% CI] declined from 53.6% [48.8%,58.3%] in 2012-2013 to 40.0% [31.3,49.1%] in 2018-2020 (25.4% reduction, p=0.007). The indirect estimate [95% CI] of HCV incidence among "new" injectors decreased from 56.1 [49.3,63.8] to 39.0/100 person-years (PYs) [29.6,51.5] (30.5% reduction, p=0.020). HCV incidence [95% CI] based on seroconversions in repeat participants (16/63 in 2012-2013 and 9/55 in 2018-2020) declined from 64.6 [39.6,105.4] to 13.8/100 PYs [7.2,26.5], respectively (78.6% reduction, p<0.001). Primary HCV incidence remains high among PWID in Athens. Consistent implementation of combined interventions, including high-coverage harm reduction programs and initiatives tailored to increase access to HCV treatment, is essential to sustain the declining trends documented during 2012-2020.Keywords: Substance Abuse, Intravenous; Hepatitis C Antibodies; Incidence.<br/
