The FDA Blocked Its Own Vaccine Safety Studies — Here's What Was in Them

Officials at the Food and Drug Administration withdrew or blocked publication of at least four taxpayer-funded studies that found widely used COVID-19 and shingles vaccines to be safe, according to reports first published by the New York Times and confirmed by multiple outlets in May 2026 [1][2][3]. The studies, which analyzed the medical records of millions of Americans, were pulled after being accepted for publication or blocked from submission to scientific conferences — raising questions about whether political considerations overrode scientific process at the nation's primary drug safety regulator.

What Was Withdrawn

The withdrawn research falls into two categories.

COVID-19 vaccine studies (withdrawn October 2025): Two studies examining vaccine safety were directed to be pulled after they had already been accepted for publication in medical journals [1][2]. One study reviewed records of approximately 7.5 million Medicare beneficiaries aged 65 and older who received COVID-19 vaccines [4][5]. It examined 14 to 17 health conditions — including heart attacks, strokes, myocarditis, and anaphylaxis — in the 21 days following vaccination, compared with the subsequent 20 days. The researchers concluded that "no other statistically significant elevations in risk were observed" aside from rare anaphylaxis cases affecting roughly one in a million recipients [2]. A second study examined vaccine safety in approximately 4.2 million recipients aged six months to 64 years, reaching similar conclusions [2].

Shingrix (shingles vaccine) studies (blocked February 2026): Two additional studies on GSK's Shingrix vaccine — one on efficacy and one on safety — were blocked when top FDA officials refused to sign off on submitting abstracts to a major drug safety conference [1][2]. The efficacy study's findings aligned with pre-approval clinical trial data. The safety study reportedly found an elevated but low risk of Guillain-Barré syndrome, a neurological condition already listed on the vaccine's label [2].

All four studies were conducted by FDA scientists using data firms to analyze patient records and cost millions of dollars in public funds [1][3].

Who Ordered the Withdrawal and Why

An HHS spokesperson, Andrew Nixon, told reporters that "the studies were withdrawn because the authors drew broad conclusions that were not supported by the underlying data" and that "the FDA acted to protect the integrity of its scientific process and ensure that any work associated with the agency meets its high standards" [1][2][3].

The withdrawals occurred while Dr. Vinay Prasad headed the FDA's vaccine office within the Center for Biologics Evaluation and Research (CBER) [2][6]. Prasad, whose brief and contentious tenure included a claim — later challenged by twelve former FDA commissioners — that COVID vaccines had caused the deaths of "at least 10" children, did not respond to press inquiries about the withdrawn studies [6][7]. He departed the agency in March 2026 after less than three months in the role, having previously left and returned within weeks in mid-2025 [6][8].

FDA Commissioner Dr. Marty Makary and HHS Secretary Robert F. Kennedy Jr. were reportedly not involved in the publication decisions directly [2]. The FDA's official scientific integrity policy, administered by the Office of Scientific Integrity established in 2009, requires that agency publications undergo internal review for technical accuracy but does not explicitly grant political appointees authority to override peer-reviewed acceptance decisions at external journals [9][10].

Whether the withdrawal followed standard documented procedures remains unclear. No public documentation of the internal review process that led to the withdrawals has been released.

Source: Multiple news sources

Data as of May 6, 2026CSV

The Broader Pattern Under Kennedy's HHS

The study withdrawals did not occur in isolation. Since Kennedy took over HHS, the department has pursued a series of actions affecting vaccine policy:

• August 2025: Kennedy announced the cancellation of at least $500 million in federally funded mRNA vaccine development contracts through BARDA, affecting 22 projects at institutions including Emory University, Pfizer, Moderna, and Sanofi Pasteur [11][12]. Kennedy justified the move by claiming mRNA vaccines "pose more risks than benefits," a statement that FactCheck.org and multiple infectious disease experts disputed [13].
• October 2025: The two COVID vaccine safety studies were withdrawn from journals.
• December 2025: Twelve former FDA commissioners — spanning administrations from both parties — published an extraordinary letter in the New England Journal of Medicine expressing "deep concern" about changes to vaccine policy under Prasad, calling his claims "a threat to evidence-based vaccine policy and public health security" [7][14].
• February 2026: The Shingrix study abstracts were blocked.
• March 2026: Prasad departed the FDA for the second time [6][8].

Kennedy also removed 17 members of the CDC's vaccine advisory committee and advocated reducing recommended childhood vaccines from 17 to 11 shots, some of which a federal judge subsequently blocked [1][15].

What Independent Scientists Say

Reaction from the scientific and public health community was sharp.

Dr. Aaron Kesselheim, a Harvard Medical School professor who studies FDA regulation, called the withdrawals "censorship" and said: "At any other time in history, this would be a major scandal that would lead to congressional hearings and resignations of leadership, and I hope that's what happens next" [2][3].

Dr. Jeanne Marrazzo characterized the action as "a pretty active act of sabotage" and a "black box of decision making around data suppression" [2].

Dr. Fiona Havers, a former CDC official, said: "HHS leaders now have a clear pattern of blocking high-quality studies that include results that don't support their overall anti-vaccine narrative. This censorship of taxpayer-funded science is extremely concerning" [1].

Mike Osterholm, a University of Minnesota infectious disease expert, speaking about the broader pattern of mRNA funding cuts, said: "I don't think I've seen a more dangerous decision in public health in my 50 years in the business" [12].

On the other side, the HHS position is that the studies contained methodological overreach — that the authors' conclusions went beyond what the data supported. The agency has not, however, specified which conclusions it considered unsupported, nor has it released the internal review documents that led to the withdrawal decision [1][2].

Public Health Exposure

The timing of the withdrawals matters because tens of millions of Americans have received or are receiving these vaccines.

For COVID-19 vaccines, approximately 7.6 million Medicare fee-for-service beneficiaries received 2023-2024 season vaccines alone [5]. During the 2025-2026 season, an estimated 22.4 million doses were administered through retail pharmacies and medical offices, with 17.5% of adults reporting vaccination as of February 2026 [16]. These figures represent only the most recent seasons; cumulative U.S. COVID-19 vaccination since rollout exceeds 670 million doses.

For Shingrix, the CDC recommends the two-dose series for all adults aged 50 and older — a population of roughly 120 million Americans [17]. The vaccine has been widely administered since its FDA approval in 2017 and is one of the most commonly given adult vaccines in the country.

The withdrawn studies covered safety data from these populations. While the findings reportedly affirmed vaccine safety, the period during which those findings were unavailable to prescribers and advisory committees represents a gap in the information landscape. Whether that gap changed any clinical decisions is difficult to quantify, but the CDC's Advisory Committee on Immunization Practices relies on exactly this type of post-market surveillance data to update its recommendations [17].

International Regulatory Context

The FDA's withdrawal stands in contrast to the approach of international regulators, who have continued to publish and update vaccine safety findings.

The European Medicines Agency (EMA) has maintained an active post-marketing surveillance program for COVID-19 vaccines, receiving over 2.2 million adverse event case reports through its EudraVigilance system by the end of 2022 [18]. The EMA identified two notable safety signals — thrombosis with thrombocytopenia syndrome (TTS) linked to adenovirus-vectored vaccines, and myocarditis/pericarditis linked to mRNA vaccines — and published its findings openly [18]. The EMA and the European Centre for Disease Prevention and Control (ECDC) also established a joint Vaccine Monitoring Platform for ongoing surveillance [18].

The UK's Medicines and Healthcare products Regulatory Agency (MHRA) has maintained its Yellow Card reporting system for COVID-19 vaccine adverse events throughout the pandemic and continues to publish summary reports [19].

A major multinational study through the Global Vaccine Data Network (GVDN), published in the journal Vaccine in 2024, analyzed data from 99 million vaccinated individuals across eight countries [20]. It identified elevated rates of Guillain-Barré syndrome and cerebral venous sinus thrombosis following certain vaccine types — findings broadly consistent with what regulatory agencies, including the FDA's own researchers, had observed. The study's findings were published and are freely available in the scientific literature.

The contrast is notable: while international bodies have continued to publish safety data — including data showing rare adverse events — the FDA under its current leadership withdrew studies that reportedly confirmed the vaccines' safety profile.

The Scientific Integrity Question

Source: OpenAlex

Data as of Jan 1, 2026CSV

The withdrawal raises a structural question about who controls publication decisions for federally funded research. The FDA's Office of Scientific Integrity, established in 2009, is tasked with ensuring that "scientific decisions are not improperly influenced" [10]. A 2010 White House Office of Science and Technology Policy memorandum directed federal agencies to allow scientists to publish findings after internal review for accuracy — not for political palatability [9].

The Scientific Integrity Act (H.R. 1106), introduced in the 119th Congress, seeks to codify protections against political interference in federal scientific work [9]. Its relevance to the current situation is direct.

Critics of vaccine policy will point to this episode as evidence of institutional suppression of safety data. The verifiable facts support a pattern: multiple studies withdrawn, funding cut, advisory committee members removed, and public statements from agency leadership questioning established vaccine science. Twelve former FDA commissioners — an unprecedented coalition — publicly warned of threats to evidence-based policy [7][14].

Alternative explanations offered by the agency — that the studies' conclusions exceeded the data — remain unsubstantiated by public documentation. No specific methodological critiques have been released. No external peer reviewers have been cited as raising concerns. The journals that had accepted the COVID vaccine studies had already subjected them to their own peer review processes [2].

At the same time, reasonable scientific debate about study methodology is standard practice, and federal agencies do have legitimate authority to review publications by their employees. The question is whether that authority was exercised here on scientific grounds or political ones — and the absence of documented justification makes it impossible to resolve that question from outside the agency.

What Comes Next

The withdrawn studies remain unpublished. The data they analyzed — drawn from millions of patient records — sits in FDA systems. Whether the studies will eventually be released, revised, or permanently shelved is unknown.

Congressional attention appears likely. Kesselheim's call for hearings echoes concerns already raised by lawmakers about HHS's vaccine policy direction. The twelve former commissioners' NEJM letter provided bipartisan institutional weight to those concerns [7][14].

For the millions of Americans who have received or will receive COVID-19 and shingles vaccines, the practical implications are limited: the withdrawn studies reportedly confirmed what the broader scientific literature already shows — that these vaccines are safe, with rare and mostly known adverse events. But the precedent of a federal agency withdrawing its own safety-affirming research, without public explanation of specific scientific deficiencies, marks a departure from established norms of regulatory transparency.