The Food and Drug Administration blocked the publication of multiple federally funded studies examining the safety of COVID-19 and shingles vaccines in recent months, prompting accusations from outside scientists and medical experts that political interference is reshaping how federal health agencies handle vaccine research.
The studies, conducted by agency-based scientists and involving millions of vaccine recipients, largely found that serious adverse events associated with the vaccines were rare. Yet despite clearing significant portions of the scientific review process, the studies were either withdrawn, delayed, or prevented from being submitted for publication and scientific conferences.
Officials at the Department of Health and Human Services confirmed that the studies had been stopped.
“The studies were withdrawn because the authors drew broad conclusions that were not supported by the underlying data,” HHS spokesperson Andrew Nixon said. “The FDA acted to protect the integrity of its scientific process and ensure that any work associated with the agency meets its high standards.”
The blocked research included two COVID-19 vaccine safety studies and studies related to the shingles vaccine Shingrix. The decisions come amid broader changes to federal vaccine policy under Health and Human Services leadership, including the rollback of mRNA vaccine development programs and revisions to childhood vaccine recommendations by advisory panels populated with vaccine skeptics.
One of the halted COVID vaccine studies analyzed records from approximately 7.5 million Medicare beneficiaries who received the updated 2023-2024 COVID vaccines. Researchers examined 14 potential health outcomes following vaccination, including stroke, pulmonary embolism, Guillain-Barré syndrome, and anaphylaxis.
According to a preprint version of the study that remains online, researchers identified only one potential elevated risk: a rare increase in anaphylaxis cases following the Pfizer-BioNTech vaccine. The rate was estimated at roughly 1 in 1 million people.
“No other statistically significant elevations in risk were observed,” the study concluded.
The second COVID-related study examined approximately 4.2 million vaccine recipients between the ages of 6 months and 64 years old. Researchers searched for 17 potential health outcomes and evaluated whether the vaccines were associated with previously documented or new adverse events.
The study identified evidence of elevated risk for some already documented rare side effects, including a statistically significant increased risk of febrile seizure following Moderna vaccination among children between 6 months and 5 years old. Researchers reported that no new safety concerns emerged across the larger study population.
“The benefits of vaccination outweigh the risks,” the study concluded.
That study was later withdrawn from the journal Vaccine in October, according to Angela Rasmussen, one of the journal’s editors in chief.
FDA officials also reportedly failed to approve submission of abstracts related to two studies on the Shingrix shingles vaccine before a drug safety conference deadline passed in February. Nixon defended the decision, stating: “The design of that study fell outside the agency’s purview.”
He did not elaborate further.
Outside experts who reviewed the studies questioned the rationale for preventing publication.
Caleb Alexander, a drug safety and methodology expert at Johns Hopkins University, told The New York Times after reviewing the reports that “there is nothing inherently problematic regarding these reports.” He added that the studies provided “useful information regarding the most commonly used COVID-19 vaccines.”
Aaron S. Kesselheim, a Harvard medical professor who studies FDA regulation, also criticized the move. Kesselheim said FDA-produced studies generally meet “the highest standards of scientific investigation” and described the decision to block the research as “censorship.”
“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,” Kesselheim said.
The controversy surrounding the blocked FDA studies follows a separate dispute involving the Centers for Disease Control and Prevention just weeks earlier.
In April, the CDC was accused of preventing publication of a report showing strong effectiveness of COVID vaccines. That report, which had already passed the agency’s review process, found that vaccinated adults experienced hospitalization rates that were 55 percent lower than those who were not vaccinated.
Then-acting CDC director Jay Bhattacharya reportedly delayed the study after raising concerns about its methodology. The agency later chose not to publish it at all.
An analysis by the Center for Infectious Disease Research and Policy at the University of Minnesota noted that “The same methodology has long been used by the CDC to evaluate vaccine effectiveness for respiratory viruses and was used in a study on the flu vaccine.”
The FDA and CDC publication disputes are unfolding as HHS pursues broader changes to vaccine policy and research priorities.
Last summer, HHS announced it was winding down development of mRNA vaccines despite extensive evidence supporting the safety and effectiveness of the technology during the COVID-19 pandemic. The department canceled 22 federal projects connected to mRNA vaccine development, representing approximately $500 million in funding.
Bill Moss, executive director of the International Vaccine Access Center at Johns Hopkins University, warned at the time that the decision could have long-term consequences for U.S. medical research and global competitiveness.
“This undermining of public confidence in and federal funding for mRNA research is really going to set us back,” Moss said. “Other countries will move forward and we will be stalled.”
Federal vaccine policy also shifted in December when a CDC vaccine advisory panel voted to reduce the recommended childhood vaccine schedule used by healthcare providers throughout the United States. The panel was reportedly composed largely of vaccine skeptics appointed by Robert F. Kennedy Jr. the previous year.
Supporters of the changes reportedly argued that the revised recommendations would more closely align the United States with vaccine schedules used in parts of Europe. Public health experts challenged that reasoning, arguing that vaccination strategies are developed around the specific disease conditions and health needs of individual populations.
“Public health is not one size fits all. It’s population-specific and dynamic,” said Anders Hviid of Denmark’s Statens Serum Institute.
The blocked FDA studies have intensified concerns among researchers who warn that suppressing publicly funded scientific findings could erode trust in federal health institutions and undermine confidence in the scientific review process itself. The studies did not conclude that vaccines were risk-free, but they largely reinforced existing evidence that severe adverse events remained rare while documenting known complications already monitored by health authorities.
Critics argue that withholding such findings from publication may ultimately deepen public suspicion by creating the appearance that scientific conclusions are being shaped by political priorities rather than openly debated through peer review and transparent publication.
“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,” Kesselheim said.
COMMENTS