Progress: CDC no longer recommends routine COVID vaccination for children after FDA study finds increased risk of seizures

• A peer-reviewed FDA study found a statistically significant increased risk of febrile seizures in young children within one day of receiving the Moderna COVID-19 vaccine.
• The risk was approximately 2.5 times higher for children aged 2-4 in the 0-1 days after vaccination compared to a later control period.
• A similar analysis for the Pfizer vaccine showed an elevated risk, but it was not statistically significant in this study.
• The CDC no longer recommends routine COVID-19 vaccination for children, advising “individual-based decision-making.”
• Experts debate the long-term implications of febrile seizures, with some research linking them to an increased risk of epilepsy and cognitive deficits.

In a significant development for post-market vaccine safety surveillance, a study led by the U.S. Food and Drug Administration has identified a clear safety signal: Young children who received Moderna’s mRNA COVID-19 vaccine faced a substantially higher short-term risk of febrile seizures. The peer-reviewed research, published in the journal Vaccine, confirms preliminary data and raises urgent questions about risk communication and the long-term implications for pediatric health. This finding arrives at a pivotal moment, as public health guidance has shifted away from blanket recommendations for childhood COVID-19 vaccination, placing the onus of risk-benefit analysis squarely on parents and clinicians.

The FDA’s findings: A statistically significant signal

The FDA-conducted study, part of its Biologics Effectiveness and Safety (BEST) System, analyzed health insurance claims for children aged 2 to 5 years from mid-2022 to mid-2023. Researchers employed a self-controlled case series method, comparing the rate of febrile seizures in the 0-1 days immediately following vaccination to the rate in a control period of 8-63 days post-vaccination. The results were striking for the Moderna (mRNA-1273) vaccine, showing a statistically significant increased incidence, with an Incidence Rate Ratio (IRR) of 2.52. This means the risk of a febrile seizure in the first day after vaccination was roughly two-and-a-half times higher than in the subsequent control window. For the Pfizer (BNT162b2) vaccine, the IRR was elevated at 1.41, but this finding was not statistically significant within the study’s parameters.

Context and contention: From “mild” event to long-term concern

Febrile seizures, convulsions triggered by fever, are described by many health authorities as generally brief and not causing permanent harm. However, the study has ignited a debate among scientists about downplaying these events. Critics point to established research indicating potential long-term consequences. A 2024 review in Pediatric Neurology concluded that febrile seizures can lead to lifelong issues such as cognitive deficits and brain abnormalities in a subset of children. Furthermore, some experts note that even so-called “mild” febrile seizures can double a child’s future risk of an epilepsy diagnosis. This historical context—where acute vaccine reactions are often framed as transient—clashes with a growing body of literature on neurodevelopmental impacts, making the FDA’s signal a flashpoint in the discussion of vaccine safety paradigms.

A shift in policy and the question of communication

The FDA study’s publication coincides with a major shift in official public health stance. As of October 2025, the Centers for Disease Control and Prevention no longer recommends routine COVID-19 vaccination for children, instead advising “individual-based decision-making” for those 6 months and older. This change reframes the vaccination decision from a public health imperative to a personal medical choice, where understanding specific risks becomes paramount. The study also raises questions about transparency, as the FDA did not clarify whether it publicly announced this safety signal when the data was first published as a preprint in March 2024. Notably, just last month, the FDA requested that manufacturers of several flu vaccines add warnings about febrile seizure risks for young children.

Mechanisms and lingering questions

Scientists suggest biological plausibility for the differential risk between the two mRNA vaccines. A pediatric dose of the Moderna vaccine contains 25 micrograms of mRNA, compared to just 3 micrograms in Pfizer’s pediatric dose. The higher antigen load may provoke a stronger immune response, including fever, which can trigger seizures in susceptible children. Some researchers have also pointed to concerns about DNA contamination in the manufacturing process as a potential factor that could acutely activate the innate immune system. While the study focused on acute events within a 63-day window, it was not designed to assess potential long-term neurological harm, leaving a critical gap in understanding the full scope of vaccine safety for the developing brain.

Navigating a new landscape of risk and choice

The FDA’s identification of a febrile seizure safety signal represents a crucial piece of evidence in the evolving narrative of COVID-19 vaccine safety. It validates earlier reports and provides quantified risk data at a time when vaccination for children is no longer universally advised but is a matter of individual choice. For parents and physicians, the study underscores the necessity of informed consent—one that weighs the diminishing risk of severe COVID-19 in young children against the potential for acute neurological reactions and their possible sequelae. As the medical community grapples with these findings, the episode highlights the enduring importance of robust, transparent post-market surveillance and the complex task of communicating nuanced risk in an era of heightened scrutiny. The signal has been detected; the conversation about its meaning and the path forward has only just begun.

Sources for this article include:

ChildrensHealthDefense.org

ScienceDirect.com

CDC.gov