The tuberculin reaction after B.C.G. vaccination revealed weaker than that of natural
infection and it decreases gradually with the elapse of time and disappears after four or
five years. But, as a matter of fact, the positive rate of tuberculin reaction at four or
five years after B.C.G. vaccination was estimated to 5o per cent. This suggests that the
reinfection has been taken palce to those lost tuberculin allergy after B.C.G. vaccination.
Following results were obtained after comparing the pattern of tuberculin reactions
between those B.C.G. vaccinated and those naturally infected.
1. The stronger reactions were observed in the naturally acquired positive reactors
than those B.C.G. vaccinated. Of those positive reactors in the B.C.G. vaccinated, it was
noted that erythema in 50-70%, palpable induration in 20-50%, double erythema in
5-35% and vesicle and necrosis in 2-10% whereas, 2-10%, 40-60%, 10-40%, and
5-25%respectively among the naturally acquired positive reactors.
2. There was a close relationship between the frequence of B.C.G. inoculation and the
sizes of reaction after reinfection, that is, the more the frequent inoculation the weaker
the reaction of tuberculin allergy.
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