Seizure Risk with MMR Vaccine Slight, Temporary

Vaccination with the measles, mumps, and rubella (MMR) vaccine appears to increase a child’s risk of having a seizure from a high fever — a usually harmless event. However, the increased risk appears to be small and short-lived, Danish researchers report.

Vaccination with the measles, mumps, and rubella (MMR) vaccine appears to increase a child’s risk of having a seizure from a high fever — a usually harmless event. However, the increased risk appears to be small and short-lived, Danish researchers report.Moreover, like other febrile seizures, those arising after vaccination were not associated with an increased risk of developing epilepsy.The findings, which appear in the Journal of the American Medical Association, are based on a study of all children born in Denmark between 1991 and 1998 who survived at least 3 months. More than 535,000 children were followed through 1999.A total of 439,251 children (82 percent) were given the MMR vaccine, lead author Dr. Mogens Vestergaard, from Aarhus University, and colleagues note. Of all children studied, 17,986 experienced febrile seizures at least once.Within two weeks of vaccination, immunized children were nearly three times more likely to develop febrile seizures than children who were not vaccinated. Beyond this point, however, the risk of seizures in each group was comparable.A personal or sibling history of febrile seizures greatly increased the risk of seizures following MMR vaccination, but the actual risk was still small.Specifically, at 15 to 17 months, the overall rate of seizures within 2 weeks of vaccination was 1.6 per 1000 children. With a personal or sibling history of seizures, the corresponding rates were 19.5 and 4.0 per 1000 children.Experiencing a febrile seizure after vaccination slightly increased the risk of a repeat seizure, but had no effect on the risk of epilepsy compared with other febrile seizures.”MMR vaccination is an effective health intervention,” the authors emphasize, “and the transient increased rate of febrile seizures was restricted to 2 weeks following vaccination.”(Source: Reuters, Journal of the American Medical Association, July 2004)