Interventions to prevent HIV and Hepatitis C among people who inject drugs: Latest evidence of effectiveness from a systematic review (2011 to 2020).

Background: Hepatitis C virus (HCV) and HIV remain prevalent among people who inject drugs (PWID) and transmission is usually associated with injecting risk behaviour (IRB). We update a 2011 review of reviews (RoR) to assess the latest evidence on the effectiveness of harm reduction interventions - drug treatment (including opioid agonist therapy [OAT]), needle and syringe programmes (NSP) and other interventions - in the prevention of HCV and HIV transmission, and related measures of infection risk (IRB and injecting frequency [IF]), among PWID.

Methods: We undertook an initial search for systematic reviews (i.