Study Shows Small Seizure Risk From Vaccine
No Evidence of Epilepsy in Connection With MMR Vaccine
July 20, 2004 -- There's no question that childhood vaccinations against measles, mumps, and rubella save lives. But this protection may come with a price -- an increased risk of fever-related seizures.
These so-called febrile seizures occur almost three times more often in kids who get vaccinated than those who don't, typically striking within two weeks following the MMR vaccine. They cause children to briefly lose consciousness, their body to shake, and their muscles to jerk, mimicking an epileptic seizure, but they usually do not cause any harm and do not cause long-term problems.
These seizures are induced by a fever caused by the vaccination and can be alarming to parents and doctors, yet there's some comforting news in a new study by Danish researchers.
In tracking some 440,000 children for seven years -- making their study among the largest to date -- they confirm earlier evidence that the vaccine-induced seizures pose no greater threat for children later developing epilepsy.
Family History Matters
However, the researchers say febrile seizures do occur more frequently in children with a sibling who has epilepsy or other family history -- even though it doesn't increase their individual risk of later developing epilepsy. This confirms data collected three years ago by Robert L. Davis, MD, MPH, a noted researcher on the effects of childhood vaccines.
But perhaps more importantly, the new report in this week's Journal of the American Medical Association offers new clues into an individual child's susceptibility of febrile seizures.
As it turns out, the researchers from Aarhus University and the Danish Epidemiology Science Centre in Copenhagen say the risk for febrile seizures following a vaccine doesn't vary by sex, social class, or birth order and is no more common in children born prematurely.
"This study is very important in that they are one of the first (research teams) to begin to address individual susceptibility to vaccine affects -- and that is what this is really about," says Davis, currently on sabbatical from the University of Washington and the Group Health Cooperative in Seattle to work at the CDC's Office of Genomics in Atlanta.