The U.S. Food and Drug Administration (FDA) released a study indicating that toddler and other young children may face a higher risk of seizures shortly after COVID-19 vaccination.
According to FDA researchers, the incidence of febrile seizures was 2.5 times higher among children within a day after receiving a Moderna shot than among the same children eight to 63 days after vaccination.
The study also showed a higher risk for febrile seizures zero to one day after receipt of a Pfizer-BioNTech dose than in the 8 to 63-day window following vaccination, but that elevated risk was not statistically significant.
Richard Forshee, deputy director of the FDA’s Office of Biostatistics and Pharmacovigilance, and other researchers conducted the self-controlled case series by analyzing data from commercial databases. The data came from CVS Health, Optum, and Carelon Research. The children were 2 to 5 years old.
The study was carried out after the researchers identifi ed seizures/convulsions as a safety signal among children aged 2 to 4 following receipt of Pfizer’s shot and among children aged 2 to 5 after a Moderna shot. Further research was needed because the method of identification, near real-time surveillance, “was designed to be sensitive but not specific for screening and detection purposes,” the researchers said.
Febrile seizures became the focus because most of the cases identified in the prior study were seizures of that type.
The two-day window used in the new study ensures that the seizure cases “are more likely to be associated with vaccination rather than other causes,” the researchers said.
Seizures that happened two to seven days after vaccination were excluded from the primary analysis.