[Diphtheria immunity in school beginners and after reimmunization with d-vaccine].

The antitoxin immune status against diphtheria was determined in 814 children, aged 6-7 years, 5-6 years after first immunization. All children were then re-immunized with d-vaccine. 4-8 weeks later antitoxin was again measured to assess the immunogenic effect of the booster injection (reduced toxoid dosage of 5 IU/0.5 ml). Although all children had been completely immunized as infants, 149 of them (18.3%) presented inadequate or no immunity to diphtheria. The booster injection resulted in a reliably protective antibody concentration of 0.1 IU/ml serum even in children with low or no longer demonstrable residual immunity. The high proportion of inadequately protected children and the further continual loss of antitoxin antibodies makes booster injection mandatory at the time of beginning school as well as in juveniles and adults. The Standing Immunization Commission of the Federal German Health Office recommends this re-immunization every 10 years in the form of combined tetanus-diphtheria immunization with Td vaccine.