Canadian experts are calling for more research into heart damage linked to Covid vaccines.
They fear the scale of the issue remains ‘under-documented’ because they say studies have been too narrow and haven’t looked at the risk of these injuries months and years after receiving the shot.
In rare cases, mRNA shots have been shown to cause myocarditis, inflammation of the heart muscle, and pericarditis, inflammation of the sac-like lining surrounding the heart.
The side effect is rare but exactly how rare is still being debated. A major 2021 study in Israel put the rate at one in 50,000. Other studies have come to vastly different estimates.
But researchers from British Columbia warn those studies have been inconsistent in how they classify ‘postvaccine’ myocarditis and pericarditis, using different timeframes to define if the conditions were directly linked to the shots.
They are calling for further research, noting that rates of the heat conditions globally have increased nearly 40 percent since the vaccines were rolled out in 2021 which needed to be explored for public health reasons.
But they also concede Covid itself has been shown to cause heart damage, which confuses the issue even more.
They wrote in the medical journal JAMA today: ‘Future studies on myocarditis and pericarditis related to COVID-19 vaccination should adopt broader diagnostic criteria, include both conditions as key outcomes, and explore the combined effects of infection and vaccination on cardiovascular health.’
Experts at the University of British Columbia filed a response this week to an August 2024 study on heart complications from Covid vaccines (stock image)
Rory Nairn (pictured here), a 26-year-old from New Zealand, died from myocarditis 12 days after receiving his first dose of the Pfizer Covid vaccine in 2021
CDC data shows postvaccine myocarditis and pericarditis are two of the few well established side effects of Covid vaccination, though the agency does not provide a number of cases.
In myocarditis, it’s thought that the immune system may register mRNA in Covid vaccines as a threat, leading the immune system to attack itself and cause inflammation of the myocardium, the heart’s muscle.
This same mechanism has been linked to pericarditis, which leads to inflammation of the pericardium, the sac surrounding the heart.
Both conditions have been linked to viruses like the common cold and hepatitis, as well as Covid.
While most cases are mild, in rare instances, myocarditis can damage the heart and make it difficult for it to pump blood, eventually leading to heart failure, heart attack, and stroke.
The Canadian experts responded this week to a French study published last year, which looked at more than 4,600 patients hospitalized for myocarditis.
A total of 558 of those patients developed ‘postvaccine myocarditis,’ while 298 had it from Covid and 3,779 had ‘conventional myocarditis,’ meaning it was unrelated to Covid or the vaccine.
The researchers found patients with postvaccine myocarditis tended to be younger and were more frequently men, and they had much milder cases than those with conventional disease.
The team concluded Covid and other conditions leading to myocarditis had more long-term harms than postvaccine myocarditis.
But, one caveat was the disease was only considered ‘postvaccine’ if it developed within seven days of vaccination.
In their response, the British Columbia researchers said the study’s seven-day window for postvaccine myocarditis is inconsistent with data from the CDC, which suggests the condition can develop up to 40 days after vaccination.
Additionally, the Vaccine Adverse Event Reporting System (VAERS), an arm of the US Department of Health and Human Services, suggested in a 2022 report myocarditis onset can start 120 days after vaccination.
The Canadian researchers said the study may be missing patients with postvaccine myocarditis due to the limited diagnostic criteria.
They also pointed out the study never looked at pericarditis.
Rhian Griffiths, from the UK, was otherwise fit and healthy when she suffered a cardiac arrest in 2023 at age 32. After her death, she was diagnosed with myocarditis. Her family suggested her ‘unknowingly catching Covid had this effect on her heart’
A 2024 study looked at the conditions most associated with Covid vaccinations. Heart issues like pericarditis and myocarditis were most often linked to the shots
The above graph shows the risk of suffering myocarditis by doses, based on people under 40 years old and up to seven days after getting their vaccine, according to a 2022 study. Risk was highest after the second dose
Authors Dr Chengliang Yang and Dr Scott J Tebbutt, from the University of British Columbia’s Departments of Medicine and Repiratory Medicine, wrote: ‘The study’s 7-day window may underestimate vaccine-associated myocarditis.’
They also suggested the researchers could have compared the findings of the post-vaccine group to those who developed myocarditis around the same time but did not receive the vaccine to compare potential mechanisms.
However, they also admitted some cases of myocarditis and pericarditis could be caused by Covid itself.
The researchers wrote: ‘Evidence indicates cardiovascular disease risk in those who previously had COVID-19 is substantial.’
They called for increased research on the subject with more long-term criteria for diagnosing postvaccine myocarditis.
The experts wrote: ‘Patients with postvaccine myocarditis may face cardiovascular outcomes influenced by both COVID-19 and vaccine-related myocarditis, complicating management and underscoring the need for further studies.’
