French bacteriologist, pupil of Louis Pasteur, and codeveloper with Camille Guérin (Guérin, Camille) of the tuberculosis vaccine Bacillus Calmette-Guérin (BCG). He also described a diagnostic test for tuberculosis, known as Calmette's reaction.

Calmette graduated in medicine in 1886 in Paris. In 1891 he founded the Pasteur Institute at Saigon, Indochina, where he discovered a protective serum against snake venom. After his return to France, he founded and became director (1896–1919) of the Pasteur Institute at Lille. There in 1908 he discovered that virulent bovine tubercle bacilli became less virulent when cultured on a bile-containing medium. These attenuated bacilli were still able to confer a certain amount of immunity against infection with either bovine or human tubercle bacilli. This avirulent strain was used to make BCG, which was introduced about 15 years later for the vaccination of children against tuberculosis. Although widely used in continental Europe, the vaccine was not adopted in the United States and Great Britain until after Calmette's death—not until American studies in 1940 and a trial sponsored by the British Medical Research Council (reported in 1956) indicated BCG's substantial protective action against tuberculosis.