Population size estimation of people who inject drugs using capture-recapture analysis of multiple respondent-driven sampling rounds: Implications for HIV/HCV burden and harm reduction service planning in Thessaloniki, Greece

Based on this community-based population size estimate, the prevalence of injection was nearly double the official national Greek average. The annual distribution of syringes should increase by 5.6 times to reach the WHO target (≥200 syringes/PWID/year). These findings demonstrate how community-based programs with multiple RDS rounds can also yield population estimates essential for evidence-based drug policy interventions.