Skip to main content

Canadian cardiologists debunk Florida COVID-19 vaccine claims


Two U.S. health agencies have published a letter warning that "misleading" claims Florida's surgeon general made about COVID-19 vaccines last month could be harmful to the public.

The U.S. Food and Drug Administration and the Centers for Disease Control sent the letter to Florida Surgeon General Joseph Ladapo on March 10 in response to a letter he wrote to them last month.

Ladapo, who was appointed by Republican Gov. Ron DeSantis, has previously attracted national scrutiny for sharing DeSantis' resistance to COVID-19 vaccine mandates and other health policies – such as mask mandates – recommended by the federal government.

In his Feb. 15 letter to the federal agencies, Ladapo claimed Florida had recorded a significant surge in VAERS (vaccine adverse event reporting system) reports related to COVID-19 vaccinations.

"We saw a 1,700 per cent increase in reports after the release of the COVID-I9 vaccine, compared to an increase of 400 per cent in vaccine administration for the same period," Ladapo wrote, though he did not say during which period the reporting took place. "The reporting of life-threatening conditions increased (by) 4,400 per cent."

He cited a "recent study" that found mRNA COVID-19 vaccines were associated with an "excess risk of serious adverse events," including blood clotting disorders, acute cardiac injuries, Bell's palsy and encephalitis. He said the "risk was 1 in 550" but did not say which specific risk the number referred to.

"To claim these vaccines are 'safe and effective' while minimizing and disregarding the adverse events is unconscionable," he wrote. The document's letterhead also bore DeSantis' name.

In their letter, the federal agencies condemned Ladapo's claims as potentially harmful misinformation.

"The claim that the increase of VAERS reports of life-threatening conditions reported from Florida and elsewhere represents an increase of risk caused by the COVID-19 vaccines is incorrect, misleading and could be harmful to the American public," said the letter signed by FDA Commissioner Robert Califf and CDC Director Rochelle Walensky.

They argued that cardiovascular experts had concluded the risk of strokes and heart attacks was lower in people who had been vaccinated, not higher, and pointed out that more than 13 billion doses of COVID-19 vaccines have been given around the world with low rates of adverse effects.

“It is the job of public health officials around the country to protect the lives of the populations they serve, particularly the vulnerable," the letter said. "Fuelling vaccine hesitancy undermines this effort."

In Canada, health-care professionals have their own concerns about the claims Ladapo's letter makes and the quality of the evidence it cites.

Dr. Peter Liu is the chief scientific officer and vice-president of research at the University of Ottawa Heart Institute. He reviewed the letter and, in a telephone interview with, said he couldn't track down any credible evidence to support many of the claims it made.

He pointed out that the letter outlines the increase in reports of vaccine-related adverse effects in percentages only, leaving out the absolute numbers and any explanation of how those percentages were calculated.

"The interpretation of all this information gets coloured, unfortunately, and this generates a lot of misinformation," he said. "A letter like this, which actually is not backed up by published data – making all these kind of percentage depictions of the data, and making a conclusion that is very difficult to verify – can lead to a lot of concerned people."

Dr. Chris Overgaard, a cardiology fellow in the division of cardiology at the University of Toronto, pointed out that Ladapo's letter also fails to state what types of cardiac events were reported.

"It's flawed from the beginning based on that," he told in a phone interview.

For example, Overgaard said that while COVID-19 vaccines can affect the heart in a range of ways, many of the most common cardiac effects – like temporary palpitations – are benign. One person might report a fluttering sensation in the chest after vaccination that resolves quickly on its own, while another might see a cardiologist about mild heart palpitations out of an abundance of caution due to an underlying heart condition.

"We do have a lot of people that come to see cardiologists either because they had COVID and they're worried about their heart or they had the vaccine and they're worried about their heart, and in the vast majority of those cases there's absolutely nothing wrong with their heart," he said.

In the absence of more information about the data presented in Ladapo's letter, Overgaard said we don't really know what the Flordia Department of Health considers a legitimate adverse effect report. Further, given how DeSantis and Ladapo have staked their positions on COVID-19 vaccination, it's hard to trust that their data gathering methods are unbiased.

DeSantis, has been accused of amplifying anti-vaccine conspiracy theories and misinformation by the U.S. House of Representatives Select Subcommittee on the Coronavirus Crisis, and Ladapo has a history of repeating anti-vaccination and anti-mask messaging, including on several far-right podcasts.


A separate notice published in tandem with Ladapo's letter cites several studies as offering evidence COVID-19 vaccines pose more harm than COVID-19 infections. However, those studies have been criticized within the medical community for cherry-picking and misrepresenting data to support a pre-determined conclusion.

For example, in an article published to the website Science Based Medicine in July 2022, New York-based neurologist and science writer Dr. Jonathan Howard claimed that one of the studies, titled "Serious adverse events of special interest following mRNA COVID-19 vaccination in randomized trials in adults," inflated potential harms linked to the vaccine compared with harms linked to COVID-19.

"A single person who had gastroenteritis and abdominal pain after vaccination was counted as having two adverse events, while someone who was hospitalized with COVID, was counted once, even if they experienced a multitude of grave complications as a result," Howard wrote.

In a video posted to YouTube, in June 2022, Susan Oliver, a scientist with a PhD in nanomedicine, further explained how the authors of the study had used a technique called data dredging or "p-hacking" to misrepresent the data reported within the study.

"It's basically just a rubbish paper that uses a technique known as 'p-hacking' followed by some apples-to-oranges comparisons," she said. "Essentially, p-hacking occurs when researchers collect or select data or statistical analyses until non-significant results become significant. If their original analysis doesn't show any statistically significant difference between the data, then they keep analyzing different subsets until they find something that is significant."

In other words, p-hacking allows someone who has made a pre-determined conclusion to manipulate the data until it supports that conclusion.

Another of the studies cited by Ladapo, titled "MIT study finds COVID vaccines 'significantly associated' with jump in emergency heart problems," was debunked by Reuters Fact Check in May of 2022. Reuters argued the study implied the emergency heart problems it discussed were caused by COVID-19 vaccines, but failed to show any correlation between the two.

Neither Liu nor Overgaard deny there are cardiac and cardiopulmonary risks associated with COVID-19 mRNA vaccines. However, both say a growing body of publicly accessible, scientifically validated evidence shows that, for most people, the benefits of vaccination far outweigh the risks.

“The risks of severe cardiac illness with COVID-19 are far greater than the risks of the vaccine,” Overgaard said.

With files from the Associated Press Top Stories

Local Spotlight

'It was surreal': Ontario mother gives birth to son on day of solar eclipse

For many, Monday's total solar eclipse will become a distant memory or collection of photos to scroll through in the years to come. But for Alannah Duarte and her family, they'll be reminded of the rare celestial event every year they celebrate their youngest son's birthday, as he was born on the day of the momentous occasion.