Andrew Bridgen misrepresents study in letter to PM

15 August 2023
What was claimed

The Moderna vaccine causes a one in 35 chance of heart damage following a third dose.

Our verdict

A Swiss study reports this rate of people having temporary, mild increases in a blood marker that can indicate heart damage. But none of the people in the study had confirmed heart problems diagnosed, and it is questionable if the blood marker is of clinical relevance on its own.

I have been provided with recently peer-reviewed scientific evidence from a Swiss study conducted by the Basel Cardiovascular Research Institute which reveals a 1 in 35 chance of heart damage following three shots of the Moderna mRNA-1273 vaccine.

A letter written from Reclaim MP Andrew Bridgen to Prime Minister Rishi Sunak, which Mr Bridgen has posted on Twitter, references a Swiss study claiming to have found a one in 35 chance of heart damage after a course of the Moderna Covid-19 vaccine. This is a misleading and inaccurate interpretation of the study.

The letter is requesting a recall of parliament (which is currently on summer recess) in order to stop the Covid vaccine booster programme “given the gravity of the peer-reviewed revelation”.

But there are serious limitations to the study, which in any case found no clinically important results.

Similar claims based on the study have been made on social media, with the one in 35 claim being repeated widely.

The MP for North West Leicestershire was expelled from the Conservative Party earlier this year after sharing a tweet comparing the Covid vaccines and the Holocaust, and is now a representative for The Reclaim Party. We have fact checked Mr Bridgen many times as well as writing about other false and misleading Covid vaccine claims. Vaccine misinformation can harm health, as people may make decisions based on it. 

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The Swiss study

Mr Bridgen appears to be referencing a study published in July. This study looked at hospital workers scheduled to have a booster dose of the Moderna vaccine

We have written about this study before, when an early version of it (that had not yet been peer-reviewed or published in a journal) was the basis of false claims about myocarditis rates after vaccination.

Myocarditis is an inflammation of the muscular wall of the heart (the myocardium), most often caused by viral infection. Common symptoms include chest pain, fever and tiredness.

The researchers measured troponin levels, which is a marker of possible damage to the heart. It can also be raised temporarily after strenuous exercise or during illnesses like infections or irregular heartbeats, which doesn’t necessarily mean the heart has been damaged in any permanent way.

The study found that of the 777 workers included who had boosters, 40 had a troponin level above the normal range at day three post vaccine. 18 of these were deemed to have alternative causes of their raised troponin, all of which the researchers felt were likely pre-existing conditions.

This left 22 participants without alternative causes identified, meaning they were classed as having “vaccine-associated myocardial injury”. They compared this group to control–patients who hadn’t had boosters but were of matching age, sex and heart disease history.

20 of the group were women, two were men. This 22 figure corresponds to one in 35 of the overall cohort.

The “gravity of the peer-reviewed revelation”

Mr Bridgen has represented this study as a reason to immediately pause further boosters.

However, the study authors don’t share this view. The study says:

“The long-term consequences of [these findings] are unknown [but] good long-term out-comes can be expected. COVID-19 associates with a substantially higher risk for myocarditis [than] mRNA vaccination, and myocarditis related to COVID-19 infection has shown a higher mortality than myocarditis related to mRNA vaccination. Thus, for the majority of individuals, the overall very favourable risk–benefit ratio of booster immunizations persists.”


There are further issues with the study that make it less convincing as evidence for the risk of booster vaccination.

The troponin rises were small and temporary, with the study noting “all cases were mild with only a transient and short period of myocardial injury”.

Dr James de Lemos, an American Heart Association expert and chief of the Division of Cardiology at UT Southwestern Medical Center in Dallas told fact checkers Lead Stories as part of a similar fact check that “These small troponin elevations are not likely events of clinical significance.”

Troponin is only one part of the picture when looking for heart damage. Other tests, such as ECGs (a tracing of the electrical activity of the heart) and scans to look at the heart itself are important. The study included ECGs, and found nothing. They did not do any imaging, which is noted as a limitation.

Additionally, troponin levels of participants weren’t measured before they had the vaccines, so we don’t actually know if there was a rise, or if there was when that rise occurred.

The study states “No definitive case of myocarditis was found”, and none of the participants had major adverse cardiac events (like heart attacks or death) 30 days later. Two of the cases were deemed to have probable myocarditis.

Featured image courtesy of Governor Tom Wolf

Update 8 September 2023

This article has been updated to include similar claims on social media, and to reflect ratings on these posts as part of our work with Meta.

We deserve better than bad information.

After we published this fact check, we contacted Andrew Bridgen to request a correction regarding this claim.

Mr Bridgen did not respond. 

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