Simmons B, et al. - Via a difference-in-differences analysis, researchers assessed the impact of voluntary licenses on access to hepatitis C virus (HCV) treatment. Thirty-five countries were involved in the panel, with 19 in the intervention group and 16 in the control group. Voluntary licenses were correlated with an improvement in the annual number of people accessing HCV treatment of 69.3 per 1,000 diagnosed in the simplest model, adjusting only for country and year fixed impacts. This increase was 53.6 per 1,000 diagnosed following adjustment for country-level covariates. The influence of licensing progressed over time and was biggest in the second year following implementation. Voluntary licensing initiatives seemed to substantially enhance HCV treatment uptake in qualified countries. This evidence supports expanding licensing approaches to involve more countries and more treatments.