High rate of HCV reinfection and the efficacy of standard regimens in men who have sex with men living with HIV.

In Japan, the prevalence of chronic hepatitis C virus (HCV) infection has declined due to the widespread use of direct-acting antivirals (DAAs). However, sexually transmitted HCV remains a concern among people with HIV (PWH), especially men who have sex with men (MSM). We examined PWH newly diagnosed with HCV infection between 2015 and 2024, focusing on reinfections. During this 10-year period, 26 cases were identified (incidence rate: 5.0 per 1000 person-years; 95 % CI: 3.2-7.3), including 7 reinfections (27 %). None experienced more than two episodes. Among the reinfection cases, two individuals without prior DAA treatment received sofosbuvir/ledipasvir for 12 weeks, while five with prior treatment received glecaprevir/pibrentasvir for 8 weeks. All achieved sustained virologic response, and no spontaneous clearance or relapse was observed. Unlike virologic failure, reinfection represents a new, treatable episode. Standard first-line regimens were effective without requiring longer or more costly therapies. These findings support the need to reframe HCV as a recurrent sexually transmitted infection. To ensure sustainable control in high-risk populations, healthcare systems must evolve to allow HCV treatment to be accessible, affordable, and repeatable, as is the case with the management of other common STIs.