The Tuberculin Reaction in Relation to the Local Reaction to Bcg Vaccine in Initially Vaccinated and in Previously Vaccinated Persons

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Abstract
Summary and Conclusions: The local reaction to the simultaneous but separate intracutaneous injection of 0.1 mg old tuberculin and 0.1 mg BCG vaccine was studied 48 hours after injection in a total of 3,510 unvaccinated persons, and in 99 persons previously vaccinated with BCG vaccine. Among those not previously vaccinated who failed to react to 0.1 mg old tuberculin only a small per cent showed an exaggerated local inflammatory reaction to BCG vaccine (Koch phenomenon). A high per cent of those previously vaccinated who gave a doubtful or positive reaction to 0.1 mg old tuberculin showed an exaggerated local inflammatory reaction. Of the 99 persons vaccinated one year previously, who gave a slightly positive, doubtful, or negative reaction to 0.1 mg old tuberculin, a higher per cent showed an exaggerated or accelerated reaction to the BCG vaccine after revaccination than was noted among those not previously vaccinated. A higher per cent of previously vaccinated persons reacted to reinoculation of BCG vaccine than to 1.0 mg old tuberculin. The intracutaneous injection of BCG vaccine is suggested as a test in apparent instances of anergy in suspected tuberculous infection. Such a test could be used to determine the occurrence of hypersensitivity to the bacillary bodies in the absence of appreciable tuberculin hypersensitivity. We have not observed any untoward reactions using this procedure.