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 reassures viewers that their opinion is still right and that Macs are in fact better than PCs. The inoculation theory in these ads keep Mac users coming back for Apple products and may even have them coming back sooner for the bigger and better products that Apple is releasing. That last part is especially important in a field like technology because it is continually changing and something new is always being pushed out onto the shelves. An example of inoculation theory usage in politics are present in studies indicating that it is possible to inoculate political supporters of a candidate