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 of tons in a single day. The Federal Trade Commission doesn't think that's significant." Hunt used this real-life message as an inoculation treatment in his research (Lessne and Didow, 1987). He used the corrective campaign by the FTC as the attack on the positive attitude toward Chevron. The results indicated that a supportive treatment offered less resistance than a refutational treatment. The other discovery was that when an inoculative treatment is received, but no attack is followed there is a drop in attitude. One of the major limitations in this study was that Hunt did not allow a time elapse