BCG-induced allergy and immunity in guinea-pigs during the first year after vaccination.

It has been traditional practice in many countries to let revaccination with BCG depend on the outcome of periodically repeated tuberculin testing. Acquired resistance to tuberculosis and tuberculin skin sensitivity are concomitant results of BCG vaccination, and it is apparently inferred that a waning resistance will be faithfully reflected in a waning tuberculin sensitivity. However, it has been demonstrated in recent years, both in man and in animals, that the waning of tuberculin sensitivity may be prevented merely by a repetition of the tuberculin test, while data presented in this and a following report indicate that tuberculin testing has no such influence on the course of BCG-induced resistance to tuberculosis.