May 21, 2014

Delaying measles-related vaccines may raise seizure risk


Stick to the recommended schedule

Some parents who question the safety and efficacy of vaccinations are spreading out the timing of vaccinations in their young children. But delaying the first dose of the measles-mumps-rubella (MMR) and measles-mumps-rubella-varicella (MMRV) vaccines in children older than 15 months—outside the recommended schedule—may actually more than double the risk of fever-related seizures. That new finding was co-authored by Group Health Research Institute Senior Investigator Jennifer Nelson, PhD.

Dr. Simon Hambidge, a pediatric vaccination expert with Kaiser Permanente Colorado, led the study of more than 300,000 American children from the Vaccine Safety Datalink, which includes Group Health. Pediatrics published the findings on Monday, May 19.

The study concludes post-vaccination seizure risk is not increased regardless of the timing of the vaccinations as long as they happen in the first year of children’s life. But delaying measles vaccines until after children are 15 months old may more than double their seizure risk.

Fortunately, the seizure-related risks, most often the results of a high-fever reaction from the vaccine, typically cause no long-term damage. Still, the seizures do tend to scare parents—and raise many questions.

Regardless of the risk of seizures, the study recommends babies and young children be immunized according to approved schedules. The U.S. Centers for Disease Control and Prevention (CDC) recommends a first dose of either the MMR or MMRV vaccine at 12–15 months and a second dose at 4–6 years. For more information about immunization schedules, visit the CDC.

The study was reported by media outlets including CNN, DailyRx, and the syndicated service HealthDay.


by Julian Rogers

KPWHRI in the media