Combination Vaccine Therapy Linked to Higher Risk of Febrile Seizures

Kaiser Permanente researchers have found that very young children vaccinated with a combination measles, mumps, and rubella and chickenpox vaccine are more likely to experience febrile seizures than children vaccinated separately for MMR and chickenpox.

The combination vaccine for measles, mumps, rubella, and chickenpox is associated with double the risk of febrile seizures for 1 and 2 year-old children compared to same-day administration of separate vaccinations for MMR and chicken pox (the varicella vaccine), according to Kaiser Permanente researchers.

The team used electronic health records and the Vaccine Safety Datalink data from 2000-2008 to assess seizure visits for children between 12 and 23 months following the combination vaccines and separate vaccinations for both V and MMR. Children receiving the combination were at a two-fold increased risk of fever and febrile seizures within 7-10 days of vaccination, compared to children who received same-day administration of separate vaccines. The researchers note that the increased risk with the combination was not high, but it was higher than the risk for children receiving the vaccines separately. The study “found no evidence of an increased febrile seizure risk after any measles vaccine beyond 7—10 days post vaccination.”

“While this study and the resulting CDC recommendations are very important and ones our pediatricians will follow, it is also important to emphasize that it is more common for a child to have a febrile seizure caused by a simple cold than by an immunization,” said Randy Bergen, MD, a Kaiser Permanente pediatrician and infectious disease specialist. “And though febrile seizures are a very scary event for a family, they are not dangerous and do not lead to later epilepsy or seizure disorders.”

The CDC recently recommended that pediatricians can use either vaccine for the first dose for 1-2 year olds, but “families without a strong preference for MMRV should receive separate MMR +V vaccines,” said lead investigator Nicola Klein, MD, PhD, co-director of the Kaiser Permanente Vaccine Study Center and lead author of the study in Pediatrics.

Klein added the Vaccine Safety Datalink used to complete the study “is a premiere example of how different managed care organizations can leverage their electronic medical records to improve vaccine safety and monitoring.”