FDA Examines Possible Adult Deaths From Covid Shots in Probe

The Food and Drug Administration is investigating whether Covid-19 vaccines caused deaths in adults, as part of a safety review that earlier appeared to just be focused on children.

The investigation, being conducted across different divisions of the FDA, comes at a time when US Health and Human Services Secretary Robert F. Kennedy Jr. is upending longstanding guidance for a wide range of vaccines.

The “FDA is doing a thorough investigation, across multiple age groups, of deaths potentially related to Covid vaccines,” a spokesperson said in a statement to Bloomberg Tuesday.

Numerous studies have shown that Covid vaccines are safe but Kennedy has repeatedly called the safety and efficacy of the shots into question. He has also canceled hundreds of millions of dollars in funding for mRNA vaccines, the technology underpinning Moderna Inc.’s and Pfizer Inc.’s Covid shots.

Moderna shares briefly turned negative before gaining 1% at the market close in New York Tuesday. Pfizer fell 1.7%.

Pfizer and Moderna’s Covid franchises were already under pressure as the pandemic faded and most people have opted to skip yearly shots. But Covid vaccines still accounted for billions of dollars in revenue for the companies in 2024.

A spokesperson for Moderna pointed to a statement from September saying the safety of its vaccine is rigorously monitored by the company and regulators in more than 90 countries. A Pfizer spokesperson pointed to a series of statements supporting the shot’s safety, saying over 5 billion doses of its vaccine have been distributed globally and that it’s “among the most extensively monitored products licensed in the world.”

Vinay Prasad, the FDA’s top vaccine regulator, last month said in a leaked internal memo viewed by Bloomberg that the agency will impose stricter standards for immunizations. He claimed, without evidence, that a review found 10 children died because they received a Covid vaccine.

A dozen of the FDA’s former leaders condemned Prasad’s new approach to vaccine regulation in an article published in a prominent medical journal.

Michael Kinch, a drug development expert and chief innovation officer at Stony Brook University, said widening the investigation could lead to increased doubt in the safety of the shots. “The actions by an irresponsible few could have long-lasting implications for the health of the many,” he said.

Covid-19 vaccinations averted 2.5 million deaths globally between 2020 and 2024, according to an analysis conducted by researchers at Stanford University and Italian universities published in July. They found the majority of the benefit was skewed toward older adults.

There have been a few reports in medical literature of deaths after Covid-19 vaccines potentially related to myocarditis, an inflammation of the heart muscle, including one American that was documented in the New England Journal of Medicine. Another study in that journal found that of 5.1 million Israelis who got the Pfizer shot, myocarditis was mild in 95% of cases, but there were a handful of severe cases and one death.

In March 2022, approximately 53% of the adult US population received the full Covid vaccine series and at least one booster shot, according to a CDC analysis. Just 23% of American adults received Covid vaccines or boosters in the respiratory illness season spanning from fall 2024 to spring 2025, CDC data shows.

The FDA is also taking a closer look at safety data for RSV shots for infants, HHS said on Tuesday. Bloomberg's Sam Fazeli joins to discuss on Bloomberg Intelligence.

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