Routine childhood vaccinations, nor the aluminum used as vaccine adjuvants, are not associated with an increased risk of epilepsy in young children, according to a new case-control study published this week in The Journal of Pediatrics.
The study, led by a team from the Marshfield Clinic Research Institute in Marshfield, Wisconsin, examined whether being up to date on recommended vaccines or having higher cumulative exposure to vaccine-related aluminum was linked to the development of epilepsy in children under age four.
Analyzing a decade of pediatric health data from the Vaccine Safety Datalink, which is a collaboration between the Centers for Disease Control and Prevention and several health care sites that monitor vaccine safety, the team identified 2,089 children diagnosed as having epilepsy from age 1 year to less than 4 years and matched them with 20,139 children without epilepsy based on age, sex, and health care site.
Most participants were boys (54%) and between the ages of 1 year and 23 months(69%). White non-Hispanics composed the largest ethnicity group in the study (40%).
No higher risk from following childhood vaccine schedule
The researchers used two measures to assess vaccine exposure: how closely children followed the Advisory Committee on Immunization Practices (ACIP) schedule for routine childhood vaccines and their cumulative aluminum exposure from vaccine adjuvants, measured in milligrams.
Aluminum salts, including formulations of aluminum hydroxide (AH), amorphous aluminum hydroxyphosphate sulfate, aluminum phosphate (AP), combined AH and AP (AH/AP), and aluminum potassium sulfate, are commonly used as adjuvants in vaccines to enhance immune response and have been a focus of safety concerns for some parents.
Neither measure was associated with a higher risk of epilepsy. The adjusted odds ratios for both measures did not exceed 1.0. Children with previously established risk factors for epilepsy, including those born prematurely, those with a history of epilepsy, and those with underlying neurologic or medical conditions, had substantially higher odds of developing the condition.
A subgroup analysis suggested that very young infants (1 to 2 months old) who received vaccines containing the adjuvant combination AH/AP appeared to have about twice the odds of an epilepsy diagnosis compared with those who did not, but the odds did not quite reach statistical significance. “Thus, a follow-up study of medical record reviewed outcomes of epilepsy and afebrile seizures in this age group may be warranted,” write the study authors.
Mounting safety evidence as feds dismantle vaccine schedule
One strength of the study was the high-level data gathered over time across multiple nationwide sites, but the authors also note some limitations, such as the follow-up period being restricted to early childhood, inability to account for non-vaccine aluminum exposures, and the exclusion of newer vaccines, like those that protect against COVID, respiratory syncytial virus (RSV), and influenza.
The study adds to a growing body of evidence that supports the safety of the childhood immunization schedule at a time when the ACIP and federal health agencies, under the guidance of Health and Human Services Secretary, and outspoken vaccine skeptic, Robert F. Kennedy Jr., downplay vaccines and reduce recommended childhood vaccines. Kennedy, in fact, in August 2025 demanded that a previous study showing the safety of aluminum-containing vaccines be retracted.
“Overall, this study provides additional reassurance on the safety of the childhood vaccine schedule at a time when vaccination coverage has declined in some populations,” the authors write. “These results may help providers communicate with parents concerned about potential risks of epilepsy.”
