BCG vaccine bacilli that seemed less virulent, and changed the course of their research to see if repeated subculturing would produce a strain that was attenuated enough to be considered for use as a vaccine. The BCG strain was isolated after subculturing 239 times during 13 years from virulent strain on glycerine potato medium. The research continued throughout World War I until 1919, when the now avirulent bacilli were unable to cause tuberculosis disease in research animals. Calmette and Guerin transferred to the Paris Pasteur Institute in 1919. The BCG vaccine was first used in humans in 1921. Public acceptance was slow,
BCG vaccine and lymphangiomatous spread. Regional bone infection (BCG osteomyelitis or osteitis) and disseminated BCG infection are rare complications of BCG vaccination, but potentially life-threatening. Systemic antituberculous therapy may be helpful in severe complications. If BCG is accidentally given to an immunocompromised patient (e.g., an infant with SCID), it can cause disseminated or life-threatening infection. The documented incidence of this happening is less than one per million immunizations given. In 2007, The WHO stopped recommending BCG for infants with HIV, even if there is a high risk of exposure to TB, because of the risk of disseminated BCG infection (which is approximately