Southwest China districts that had at least two household connections with leprosy were divided into one of three intervention groups for the cluster-randomized experiment. A single dose of the anti-tuberculosis medication rifampin was given to one group, one dose of the anti-tuberculosis medication rifapentine was given to another, and a control group did not receive any treatment at all. Follow-up visits were conducted annually. The primary outcome was the 4-year incidence of leprosy among household contacts. The cumulative incidence at 4 years was 0.05% in the rifapentine group, 0.19% in the rifampin group, and 0.63% in the control group according to the per-protocol analysis. There were no serious adverse events reported, and the cumulative incidence was 92% lower in the rifapentine group than in the control group. Although the cumulative incidence in the rifampin group was 79% lower than in the control group, the difference was not deemed statistically significant. "Rifapentine should now be considered in planning future trials of postexposure prophylaxis for leprosy and possibly also in any potential new version of multidrug therapy," David Scollard, MD, PhD, of the National Hansen's Disease Programs, said in a statement.