THE PURPOSE of this presentation is to review very briefly some of the history of the controversial BCG vaccine. This is a living, attenuated, bovine strain of tubercle bacilli. This strain was first isolated in Paris as a very virulent organism for animals, and it was attenuated by serial passage in artificial media for a period of 13 years.
By 1921, Calmette and Guérin were satisfied in their own minds that they had produced an attenuated bacillus, but they delayed the announcement and the distribution of cultures to other laboratories until about 1924. From 1921 to 1928, large numbers of experiments were conducted to try and revert this attenuated bacillus to its original virulent characteristic. All experimental attempts in this direction failed.
In 1930 the vaccine received a setback from which it has never fully recovered, when 240 children received it as an orally administered vaccine at Lubec and 72 of them died. 2 A full-scale investigation subsequently revealed that the BCG strain was not the cause of the disaster. A contaminating strain of bacilli in the culture administered was positively identified by growth and color-producing characteristics.
I think it is improper to speak of "a BCG vaccine." Just as the original vaccine was able to mutate from a fully virulent strain of organisms to an attenuated form, mutations continue to go on producing relative degrees of infectivity or invasiveness. There is no such thing as absolute virulence and absolute avirulence. Rather, there is a continuous spectrum of invasiveness which an organism may exhibit, and an organism may change its characteristics of invasiveness from one culture to another.
Therefore, one may read in the literature that a BCG vaccine given in Scandinavia has produced a certain amount of immunity and a certain amount of hypersensitivity, but one cannot expect to exactly reduplicate the same result here; because you just cannot get the same Scandinavian vaccine here and reduplicate that experience. In this country there are several sources of BCG vaccine that a laboratory may acquire or a physician may use.
- Copyright © 1959 by the American Academy of Pediatrics