A Phase I trial to evaluate the safety and immunogenicity of WRSs2 and WRSs3; two live oral candidate vaccines against Shigella sonnei.

•Shigella is a significant cause of morbidity and mortality among children in the developing world and travelers to endemic areas.•There are no licensed vaccines against Shigella.•The study showed the safety and immunogenicity of two live-attenuated, oral S. sonnei vaccines.•Future research will evaluate the efficacy of the vaccines against S. sonnei infection in a human challenge model.