In a memo circulated to hundreds of FDA staff on 29 November, Vinay Prasad, the new director of the U.S. Food and Drug Administration’s Center for Biologics Evaluation and Research (CBER, whose oversight encompasses vaccines) claimed, without providing any supporting data that COVID-19 vaccines had caused the deaths of at least ten children.

The claim ricocheted instantly through newsrooms and anti-vaccine circles and is continuing to do so. But many scientists, clinicians, and past and present FDA regulators—including the author of this article, a former FDA reviewer and office director—responded with astonishment and alarm.

What Prasad presented as a revelation was derived from non-validated reports by the Vaccine Adverse Event Reporting System (VAERS). VAERS is an early-warning system that collects unverified reports from all sources of adverse events reported after vaccination. Anyone can submit a report to VAERS, including patients, family members, healthcare providers, vaccine manufacturers, and the general public. The U.S. Centers for Disease Control and Prevention (CDC) and the FDA encourage anyone who experiences or knows of someone who experienced an adverse event after receiving a vaccine to report it to VAERS. These reports, as important as they are, do not by themselves establish that the adverse event was caused by the vaccination. Other systems must be used to assess whether those events are simply temporally related or were actually caused by vaccines.

The VAERS website lists these as its primary objectives:

• Detect new, unusual, or rare vaccine adverse events;
• Monitor increases in known adverse events;
• Identify potential patient risk factors for particular types of adverse events;
• Assess the safety of newly licensed vaccines;
• Determine and address possible reporting clusters (e.g., suspected localised [temporally or geographically] or product-/batch-/lot-specific adverse event reporting);
• Recognize persistent safe-use problems and administration errors;
• Provide a national safety monitoring system that extends to the entire general population for response to public health emergencies, such as a large-scale pandemic influenza vaccination program.

Prasad’s memo, which was republished by numerous outlets, announces that a review of 96 VAERS-reported paediatric deaths between 2021 and 2024 reveals that “no fewer than 10” were causally related to COVID-19 vaccination. He called this a “profound revelation” that should force sweeping changes in vaccine oversight.

But the analysis he cites contains none of the necessary scientific scaffolding. There is no information about the ages of the children, any possible comorbidities, the timelines involved, or the results of autopsies. There is no evidence that alternative causes of myocarditis—including the very common viral causes—had been ruled out. Neither are these vaccinations differentiated by manufacturer, product lot, formulation, or dose. There are no official risk estimates and there is no discussion of baseline paediatric mortality.

That VAERS reports alone are not evidence of causality is illustrated by an event that I experienced as a medical student. I had volunteered to help with a clinical trial of a cancer drug and was about to administer the 4 am dose to a patient in the clinical research unit. I was at her bedside, flicking the syringe to eject the last few air bubbles, when suddenly, she stopped breathing and expired. She was designated “Do Not Resuscitate” (DNR), so that was that. The time was 4:02. If I had given the drug at precisely 4:00, it would have appeared that the drug had caused the patient’s death, and it would likely have been reported to VAERS as a possible drug-related fatality. Therein lies the critical distinction between correlation and causation.

Definitively linking vaccinations to fatalities would need careful assessment and requires ruling out other causes of death—none of which Prasad acknowledged in his memo. Nor did he account for the fact that COVID-19 itself killed hundreds of American children during the pandemic—resulting in 821 deaths among those under nineteen in one twelve-month period, according to a 2023 JAMA study.

The review of the VAERS data was led by advisor to the FDA commissioner Tracy Beth Høeg, a physician-epidemiologist with an anti-vaccine history whose past work on post-vaccine myocarditis has been widely criticised for methodological shortcuts and selective interpretation. She conducted the review without any external oversight or independent auditing.

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As a result of a problem that has not been proven to exist, Prasad has proposed sweeping changes to long-standing vaccine-approval and oversight frameworks: expanding requirements for randomised trials in subgroups like pregnant women, revisiting the scientific basis for annual influenza-vaccine strain selection, reconsidering whether children should receive multiple vaccines during the same visit, and re-evaluating established immunologic endpoints such as antibody generation for protection from infectious agents.

In other words, vaccine developers and healthcare providers faced the prospect of policies that will slow vaccine development, markedly increase its costs, and increase vaccine hesitancy—which will undercut not just on COVID-19 vaccines but the entire architecture of modern immunisation science.

Prasad instructed staff who disagreed with his positions to “submit your resignation letters.” This is not how a government agency motivated by “gold standard and evidence-based science”—the mantra of the Trump Administration—operates. It is how an authoritarian political faction consolidates power.

The memo’s errors extended beyond methodological shortcomings to basic factual inaccuracies. Prasad implied, for example, that the federal government sets school vaccine mandates. It does not—those are state responsibilities. He criticised the CDC for not detecting myocarditis signals as quickly as Israel did, ignoring the obvious structural differences that explain the discrepancy: Israel’s population is smaller, geographically concentrated, and highly digitised, and the country adopted mRNA vaccines earlier and more uniformly than the US.

He called for randomised controlled trials in children — trials that would have been nearly impossible to execute ethically or logistically once the virus was already circulating widely and vaccines had been authorised. He suggested that the approach to influenza-vaccine strain selection for the annual vaccines required review, despite decades of global virologic surveillance and the absence of any new data that would justify upending the system. He questioned the co-administration of multiple vaccines, despite vast bodies of evidence showing that combination schedules improve uptake while not increasing the rate of adverse events. In each case, the pattern was unmistakable: a rhetorical strategy of asserting weakness or uncertainty where none exists, implying the need for radical policy reversals that align with long-standing critiques from anti-vaccine advocates.

It is impossible to divorce Prasad’s memo from the broader environment in which it arose. The Biden-era Advisory Committee on Immunization Practices (ACIP) at the Centers for Disease Control and Prevention (CDC), a consensus-driven expert panel, was summarily dismissed by Secretary of Health and Human Services Robert F. Kennedy Jr. in June and replaced with a handpicked group aligned with his scepticism of routine immunisation. Some senior CDC officials resigned in protest, while many scientists warned that decades’ worth of infrastructure designed to protect children from preventable diseases was being dismantled. Prasad’s memo fits neatly within this broader retrenchment.

The claims in the Prasad memo should have been bolstered by persuasive scientific evidence before he proposed measures that could erode confidence in paediatric vaccination, especially in the wake of historically low coverage for childhood immunisations overall.

With nearly a billion COVID-19 vaccine doses administered in the US — and close to 100 million in children—it is conceivable that adverse events might have occurred at a rate of one in ten million or one in a hundred million, but all such claims should be supported by data.

The memo arrived days before the next meeting of the CDC’s reconstituted ACIP—an advisory body now purged of much of its traditional expertise and largely populated with people unqualified or with a history of anti-vaccine views. Prasad’s unvetted analysis may be dropped on the committee with no peer review and no meaningful opportunity for scientific rebuttal.

For decades, the FDA’s vaccine division represented a model of rigorous, methodical, deliberative science. It earned trust by meticulous accumulation of evidence, by transparency of process, and by the humility that accompanies uncertainty.  If the FDA’s leadership does not correct course—through external review, internal recalibration, and/or changes in personnel—the credibility of America’s vaccine-safety enterprise will be irreparably damaged. And the casualties will include children who lose protection against preventable diseases.