Release embargoed until May 1, 1998

Contacts:
Marc Osborn
Group Health Cooperative
206-448-4148

(during the meeting):
Jennifer Donovan; 504-670-8502

Two studies offer new findings on vaccination-related seizures in children

Children are at a slightly increased risk for seizures with fever (febrile seizures) following some vaccinations, but children who have these types of seizures are not at increased risk for subsequent seizures, epilepsy, or long term psychiatric or behavioral problems, according to two recently published studies.

Measles, Mumps, Rubella (MMR) and Diptheria, Tetanus, Pertussis (DTP) immunizations appear to be associated with an increased risk of febrile seizures in children.

To find out if the long term outcomes were similar for children experiencing febrile seizures following vaccination compared to those with febrile seizures unrelated to vaccination, researchers studied 562 children with febrile seizures as part of the large CDC Vaccine Safety Datalink project in four large west coast HMOs.

Seven percent of these seizures were in children who recently had a DTP or an MMR immunization, with the rest being unrelated to vaccination. While approximately 15 percent of all the children studied had a subsequent seizure, the children with a febrile seizure following vaccination were less likely to have another seizure compared with children with febrile seizures unrelated to immunization.

Additionally, after one year, none of the children with seizures following vaccination developed epilepsy, while three percent of those having seizures unrelated to vaccination did.

Finally, children whose febrile seizure followed vaccination were no more likely to develop behavioral, learning, or psychiatric problems compared to children with febrile seizures unrelated to vaccination.

In another study, researchers assessed whether children with neurologic impairments such as cerebral palsy or developmental delay were at higher risk for seizures following a DTP vaccination, compared to children without these impairments. This study found that among a group of 13,303 neurologically-impaired children, seizures were almost six times more common. However, researchers also found that DTP vaccinations were associated with approximately a 1.7 fold elevated risk for seizures following vaccinations regardless of neurologic status. This study concluded that children with neurologic impairments are not at a particularly increased risk-compared to other children-from suffering seizures as a result of their immunizations.

The two studies were conducted as part of the CDC Vaccine Safety Datalink project-a large study of vaccine safety underway at Group Health Cooperative of Puget Sound and Kaiser Permanente. The project covers approximately 2 percent of the nation's children under age six.

Dr. Robert Davis was the lead investigator on the two studies, and represented the Group Health's Center for Health Studies and the University of Washignton. Dr. Robert S. Thompson and Dr. William Barlow also represented Group Health's Center for Health Studies. Robert Chen, Frank DeStefano, Viviana Rebolledo, and John Glasser represented the Centers for Disease Control.

Nonprofit Group Health Cooperative of Puget Sound serves more than 680,000 people across Washington state and north Idaho. The Cooperative's Center for Health Studies was formed in 1983 to conduct clinical research that would benefit not only Group Health patients, but community as well. The Center for Health Studies, together with it's partner the Center for Health Research in Portland, OR, form the nation's largest non-academically-based health research institute.

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