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 in South Dakota and had the students watch a video warning them of future pressures to smoke. In the first year, resistance was highest among those with low self-esteem (Pfau et al., 1992). At the end of the second year, students in the group showed more attitudinal resistance to smoking than they did previously (Pfau & Van Bockern 1994). Importantly, the study and its follow-up demonstrate the long-lasting effects of inoculation treatments. Other recent areas of study include vaccination safety. Wong and Harrison (2014) studied 212 female students and their attitudes about the HPV vaccine. They found that inoculation messages