[Human diploid cell (HDC) rabies vaccine immunoprophylaxis in persons at risk (author's transl)].

Twenty persons working in the institute testing rabies vaccines and sera were vaccinated three times at monthly intervals with HDC rabies vaccine. In 9 persons in whom the basic immunisation was completed more than two years previously a booster dose was given. The antibodies formed after vaccination were measured in international units (IU). Serum antibody levels rose constantly during the basic immunisation period. Four weeks after the second vaccination definite sero-conversion could be demonstrated in all persons, the mean antibody level was 6.05 IU/ml. The antibody level rose after the third vaccination to a mean of 10.7 IU/ml and sank over the following six months to 1.5 IU/ml. Two years later the mean level was 0.5 IU/ml. After boostering the antibody level rose to 29.6 IU/ml within a week and after two weeks reached one hundred fold the original level. In view of these results which agree with other studies reexamination of the present vaccination scheme for prophylactic rabies vaccination is recommended.