Studies on correlation between viability of BCG vaccine and tuberculin allergy induced by vaccination in humans

The authors describe two experiments which were carried out to determine whether, and to what extent, there is a correlation between the viability of BCG vaccine and the size of the post-vaccination tuberculin reaction is humans.In the first experiment, 28 kinds of dried vaccine were inoculated into 3028 children and the post-vaccination tuberculin reactions were examined after 1, 3-4, and 12 months. The strength of the reactions was assessed in terms of the mean size of the erythema with Old Tuberculin (OT).In the second experiment, 45 kinds of dried vaccine were inoculated into 1211 children and the tuberculin reactions were examined after 4 and 12 months. The strength of the reactions was assessed in terms of the mean size of the erythema with OT and of the induration with purified tuberculin (PPD).In both experiments, a definite positive correlation was found between the number of viable units in the vaccine and the size of the post-vaccination tuberculin reaction. This correlation was always observed up to 12 months after vaccination and held good whether the strength of the reaction was expressed in terms of erythema with OT or in terms of induration with PPD.