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May 23, 1925


JAMA. 1925;84(21):1575. doi:10.1001/jama.1925.02660470037015

Uncontrolled natural infection with tubercle bacilli immunizes to a certain degree against reinfection. If the human race acquires more or less protection by this haphazard process, it is not unreasonable to suppose that controlled inoculation might operate even more safely and effectively. Many attempts have been made, both in man and in animals, to produce an active immunity to tuberculosis by inoculation of measured doses of tubercle bacilli, living and dead, but little practical success has been thus far achieved.

The chief difficulties appear to be that the use of living tubercle bacilli as immunizing agents is dangerous, and that dead tubercle bacilli are ineffectual antigens. It is usually conceded that a parallelism exists between sensitiveness to tuberculin and immunity in tuberculosis, and it has also been commonly held that such sensitiveness develops almost solely as a result of actual infection, and only in small degree from the injection of