Abstract
Hepatitis C affects many millions of people worldwide and is at very high prevalence among people who inject drugs. In our study of hepatitis C virus (HCV) in the social networks of injecting drug users (IDUs), five IDUs with injecting careers of 9 years or more were HCV antibody and RNA negative. All injected frequently with HCV RNA-positive IDUs, and two had recently injected with the syringe of an RNA-positive IDU. Our data suggest the existence of immune protection from HCV infection.