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,
Inoculation theory widely employed concepts in the scholarly literature on persuasion” (p. 190). Involvement is critical; an individual's involvement with an issue determines how effective the inoculation process will be, if at all. If an individual does not have a vested interest in the subject, they will not perceive a threat and, consequently, will not feel the need to defend and strengthen their original opinion, rendering the inoculation process ineffective. Research during the past two decades has revealed numerous real-world applications of inoculation theory. The field of Public Relations is the perfect place for the inoculation theory to be used because the