[Seroconversion in juvenile patients and adults after diphtheria immunization].

A total of 155 persons of the Hamburg hospital personnel aged between 15 and 64 years were immunised against diphtheria. Out of 120 prevaccination seronegative persons (including very low diphtheria antitoxin titres) 92 (76.7%) reacted with seroconversion above the diphtheria protection level after the adult dosage of 7.5 IU diphtheria toxoid. Good results were still obtained with a 2.5 IU dosage. The conversion factor of 210 in the age group of 55 to 64 year old persons was sevenfold higher than in the 15 to 24 year old group. Local reactions of the mainly slight nature were seen after vaccination in 20.8%, only immunised person showed a slight increase of temperature. It is recommended to offer reimmunisation with a 7.5 IU dosage before leaving school. Selective immunisation of certain professional groups, such as hospital personnel, should be performed according to age and history, either with 7.5 or 2.5 IU of diphtheria toxoid.