P763 ANALYSIS OF HCV MARKERS AND IMMUNE RESPONSES 5–20 YEARS AFTER SUCCESSFUL HCV THERAPY SUGGESTS THAT MOST PATIENTS ARE CURED

positive at baseline and those with HCV antibody seroconversion during follow-up were tested for HCVRNA and sequenced (CoreHVR1/NS5B). Year of infection was estimated as one year after selfreported initiation of injecting. Trends in HCV genotype distribution were evaluated. Factors associated with genotype 3a infection were assessed using logistic regression. Results: Among 818 participants, HCV genotype prevalence was: G1a: 52% (n =422), G1b: 6% (n =46), G2a: 3% (n =22), G2b: 6% (n =53), G3a: 32% (n =263), G4a: <1% (n =4), G6a: 1% (n =7) and G6e: <1% (n =1). Overall, 37% were female and 21% were HIV+. The prevalence of HCV genotype 3a infection increased from 28% among those infected prior to 1980 to 40% among those infected between 1995 and 2010 (P =0.009). Factors independently associated with HCV genotype 3a infection included female sex (AOR 1.45; 95%CI 1.03, 2.03), HIV co-infection (AOR 0.65; 95%CI 0.44, 0.95) and more recent year of infection. Conclusions: The prevalence of genotype 3a infection appears to have increased among PWID in this setting. This has implications for HCV treatment as prevention strategies, given reduced efficacy of IFN-free DAA-based therapy in people with genotype 3a.