Prison-based interventions are key to achieving HCV elimination among people who inject drugs in New South Wales, Australia: A modelling study

Background & Aims: People who inject drugs (PWID) experience high incarceration rates which are associated with increased hepatitis C virus (HCV) transmission risk. We assess the importance of prison-based interventions for achieving HCV elimination among PWID in New South Wales (NSW), Australia. Methods: A model of incarceration and HCV transmission among PWID was calibrated in a Bayesian framework to epidemiological and incarceration data from NSW, incorporating elevated HCV acquisition risk among recently released PWID. We projected the contribution of differences in transmission risk during/following incarceration to HCV transmission over 2020-2029. We estimated the past and potential future impact of prison-based opioid agonist therapy (OAT; similar to 33% coverage) and HCV treatment (1500 treatments in 2019 with 32.9%-83.3% among PWID) on HCV transmission. We estimated the time until HCV incidence reduces by 80% (WHO elimination target) compared to 2016 levels with or without prison-based interventions. Results: Over 2020-2029, incarceration will contribute 23.0% (17.9-30.5) of new HCV infections. If prison-based interventions had not been implemented since 2010, HCV incidence in 2020 would have been 29.7% (95% credibility interval: 22.4-36.1) higher. If current prison and community HCV treatment rates continue, there is an 98.8% probability that elimination targets will be achieved by 2030, with this decreasing to 10.1% without current prison-based interventions. Conclusions: Existing prison-based interventions in NSW are critical components of strategies to reduce HCV incidence among PWID. Prison-based interventions are likely to be pivotal for achieving HCV elimination targets among PWID by 2030.