In 1927, Bacille Calmette-Guerin (BCG) vaccine was first used in newborns, having been developed by Albert Calmette and Camille-Guerin in 1921. BCG (live-attenuated Mycobacterium bovis BCG) represented the only vaccine against tuberculosis. It has become the most widely administered of all vaccines in the WHO Expanded Programme for Immunization, but has been estimated to prevent only 5% of all potentially vaccine-preventable deaths due to tuberculosis.