Relationship of pertussis immunization to the onset of neurologic disorders: a retrospective epidemiologic study

A retrospective epidemiologic study examining the relationship of the time of onset of neurologic disorders with the time of pertussis immunization in two cohorts of children who received pertussis immunization at different ages is reported. Before April 1970, children in Denmark were vaccinated with diphtheria and tetanus toxoids with pertussis vaccine at 5, 6, 7, and 15 months of age. Since 1970, children were given monovalent pertussis vaccine at 5 and 9 weeks and at 10 months of age. A total of 554 cases of epilepsy with onset between 28 days and 24 months of age were reviewed, 286 from the 1967-1968 period and 268 from the 1972-1973 period. There was no relationship between the age of onset of epilepsy and the scheduled age of administration of pertussis vaccine. A total of 2199 children with febrile seizures were reviewed, 830 from the 1967-1968 period and 1369 from the 1972-1973 period. There was a statistical association between first febrile seizures and the scheduled age of administration of pertussis vaccine (p = 0.004). No relationship between pertussis immunization and the occurrence of central nervous system infections was noted.