Can Hepatitis C virus treatment be used as a prevention strategy? Additional model projections for Australia and elsewhere

Zeiler et al. (2010) use a simple model to project the potential prevention utility of using pegylated interferon and ribavirin to treat active injecting drug users (IDUs) for HCV infection. Their analysis shows that increasing the level of HCV treatment in Australia could dramatically reduce the prevalence of HCV infection among IDUs. We argue that their projections are under-estimating the possible impact of HCV treatment because their assumed prevalence of active HCV infection in Australia is too high (assumed prevalence of acute plus chronic is 60%) and their model effectively assumes a treatment efficacy of 33%. We replicate their model and show that if these issues are corrected (assuming 45% prevalence of active HCV infection, i.e. 60% antibody prevalence and 50% treatment efficacy), then substantially greater impact can be achieved. In addition, we show that the effect of HCV treatment on the primary prevention of HCV increases in populations with lower background HCV prevalence. We also query their finding that HCV treatment should be preferentially targeted to IDUs not on methadone maintenance treatment.