[Response of the body to smallpox vaccination in persons with repeated negative vaccinal antecedents].

A study was carried out on the humoral response and vaccinal reaction after repeated administration of the smallpox vaccine (1 to 3 times), at ten days interval, to 97 subjects with a past history of repeated vaccination failures. Revaccination ended in 52.6% failures. After revaccination the antibody titer increased in 97.8% of the cases of successful vaccination and in 43.5% of the negative cases. In 29.5% of the latter cases a decrease in the antibody titer by 1--3 binary dilutions was found. The results suggest that the repeated application at short intervals of an antigenic stimulus perturbs the immune response.