Working toward more effective tuberculosis (TB) vaccines, researchers at Weill Cornell Medicine have developed two strains of mycobacteria with "kill switches" that can be triggered to stop the bacteria after they activate an immune response. Two preclinical studies, published Jan. 10 in Nature Microbiology, tackle the challenge of engineering bacteria that are safe for use in controlled human infection trials or as better vaccines. While TB is under control in most developed countries, the disease still kills over a million people a year worldwide.