Abstract
HIV pre-exposure prophylaxis (PrEP) has been associated with incident hepatitis C virus (HCV) infection in men who have sex with men (MSM) due to decreased condom use. We examined rates of HCV among MSM and transgender women at high-risk of HIV on PrEP in Southern California using data from two trials (NCT01761643 and NCT01781806). Five of 599 participants (0.84%, 95% CI, 0.27-1.93) had HCV antibodies detected at entry. Factors associated with HCV seropositivity included being older (p = .002) and lower education level (p < .001). HCV-positive participants had no reported cases of sexually transmitted infection (rectal, urethral or pharyngeal gonorrhoea and/or chlamydia) at entry while HCV-negative participants had a prevalence of 18% (95% CI, 15%-21%). There were no significant differences in substance use and sexual risk behaviour between HCV-positive and HCV-negative participants 1-3 months prior to entry. Among early PrEP adopters, incident HCV did not occur despite ongoing condomless intercourse. Screening intervals for HCV in MSM on PrEP should be led by a risk behaviour assessment.