Senate Report: Early COVID Vaccine Warning Signs Were Overlooked

Internal records show officials reviewed potential warning signals and debated how to handle the findings during the initial rollout

WASHINGTON — A report released Tuesday by the U.S. Senate Permanent Subcommittee on Investigations, led by Chairman Ron Johnson, alleges federal health officials failed to act on early warning signs of potential adverse events linked to COVID-19 vaccines and instead limited internal analysis and communication of those findings.

The majority staff interim report, released in conjunction with an April 29, 2026 hearing, cites internal records from the Department of Health and Human Services showing that as early as 2021, a senior Food and Drug Administration official identified dozens of statistically significant safety signals using an alternative data analysis method.

According to the report, Dr. Ana Szarfman, a medical officer and data mining developer at the FDA, conducted analyses in March 2021 using a newer methodology designed to address known limitations in the agency’s existing system. That analysis identified “49 examples of extreme masking,” including approximately 25 statistically significant safety signals for adverse events that were not detected using the FDA’s standard method.

Among the adverse events identified were sudden cardiac death, Bell’s palsy and pulmonary infarction, according to the report.

The report states Szarfman shared her findings multiple times with senior FDA officials in 2021, including additional analyses in April, May and July that identified further signals tied to conditions such as acute myocardial infarction, embolism, thrombosis and death associated with COVID-19 vaccines.

However, the report alleges that instead of acting on those findings, federal health officials instructed Szarfman to stop producing and distributing her analyses. Internal communications cited in the report show FDA officials directing her to “hold off on creating and sending data mining reports and analyses.”

The report also cites an email from a senior FDA official expressing concern that the analyses could “create erroneous conflicts that feed in to anti-vaccination rhetoric.”

According to the report, FDA officials continued to rely on their existing empirical Bayesian data mining system, known as MGPS, which the document describes as having limitations, including a statistical effect known as “masking.” That effect can obscure safety signals when large volumes of similar data are combined, potentially preventing detection of adverse events.

Szarfman and collaborator Dr. William DuMouchel promoted a newer method, called Regression-Adjusted Gamma Poisson Shrinker, or RGPS, which they said better accounted for masking and reduced missed signals. The report states FDA did not adopt the updated method despite repeated recommendations.

The document further alleges that federal officials acknowledged certain risks internally, including a May 2021 discussion noting that the Vaccine Adverse Event Reporting System was signaling for myocarditis in younger age groups.

Despite that, the report states that officials did not immediately issue public warnings, noting that label changes for myocarditis were not announced until late June 2021.

The report also raises concerns about transparency, stating that FDA officials moved to limit distribution of internal data mining reports in 2022. Emails cited in the document indicate that weekly reports were eventually discontinued and access restricted, with some officials referencing Freedom of Information Act requests as a factor.

Additionally, the report says FDA officials were instructed to cease certain analyses and avoid sharing internal findings externally, while continuing to rely on existing monitoring systems.

The report concludes that federal health officials were aware of limitations in their data analysis methods, including the potential for missed safety signals, but did not implement recommended changes during the initial vaccine rollout.

The findings are part of an ongoing congressional investigation into the federal government’s handling of COVID-19 vaccine safety monitoring and internal communications during the pandemic.