Severe reactions experienced by 60 children within 48 hours of DTP immunization were reported from the UCLA School of Medicine, Los Angeles, CA. These included seizures in 40 or 66% (6 with fever >40.5°C), collapse episodes in 14, and persistent crying in 6. Subjects with encephalopathy were not included in the study. Those with seizures had a high rate of personal and family histories of seizures, and 10% were afebrile. Chinese hamster ovary cell assays failed to reveal active pertussis toxin in acute sera. Long-term follow-up for possible neurologic sequelae was not performed. 
COMMENT. Seizures induced by pertussis immunization and fever are more severe than simple febrile seizures. Cherry JD and associates report that a first febrile convulsion within 3 or 7 days of pertussis immunization is more likely to last longer than 10 minutes, to be recurrent, and to have a focal pattern when compared to first seizures occurring more than 7 days after immunization . They have estimated that one in a 1000 children immunized will have a seizure, and 6% of first febrile seizures are associated with pertussis immunization. The use of acellular DTP vaccines, recently approved by the FDA, may hopefully reduce the frequency and severity of neurological complications.