Heart problems after Covid injections are very rare, but research lacks clarity



Studies show that the risk of developing heart disease after the introduction of the Covid mRNA vaccine is very low, and this should not call into question the value of life-saving vaccination campaigns deployed around the world.

But the risk is “negligible” and the available evidence is difficult to accurately assess, the researchers say, calling for more precise data on the matter.

“The fact that we have been mass mRNA vaccination for over a year and a half and are still unsure about the frequency of this clinically important outcome is disappointing,” US researchers Jing Luo and Walid Gellad wrote in a commentary in the journal BMJ. in the middle of July.

Their opinion was based on a large study in the same issue that looked at available studies on the incidence of myocarditis and pericarditis, two inflammations in the heart, following vaccination with Pfizer and Moderna mRNA. shots.

It was a sensitive topic for the scientific community. The risks were quickly identified after the launch of mass vaccination campaigns last year, but were then greatly exaggerated by vaccine skeptics seeking to oppose all vaccinations.

Heart disease after vaccination occurred very rarely and in most cases did not cause serious complications. The fact that Covid itself poses a risk of cardiovascular disease is also part of the equation.

– “A matter of great importance” –

Thus, the value of mRNA vaccines was not questioned. But for researchers writing in the BMJ, the current level of risk knowledge remains inadequate.

“Obviously, cases of myocarditis after vaccination are rare,” they wrote. “How rare remains a matter of great importance.”

The review they commented on, in which other researchers analyzed the results of about 50 previous studies, provides some answers.

This largely confirmed previous findings, including that the risk of myocarditis after vaccination appears to be higher for young men than for any other group.

While the findings are less clear, the risk is slightly higher after a dose of Moderna compared to Pfizer.

This appears to reinforce the decision of some countries, including France, to only allow Moderna Covid vaccinations for people over the age of 30. Other countries, such as the United States, did not make this distinction.

The study pointed to a lack of clarity in other areas.

It has been found that some results may vary greatly between different methodologies, while others may be considered unsatisfactory.

This was the case with a particularly sensitive topic: the vaccination of children.

Many countries allow vaccination of young children, but implementation has often been sluggish due in part to parental reluctance.

Myocarditis in children aged 5 to 11 is “very rare,” the researchers said, but added that “certainty was low.”

– Boosters are less risky? –

The researchers raised other questions.

Most cases of myocarditis and pericarditis resolved without serious complications. But they were rarely followed up for an extended period of time, meaning they couldn’t rule out future complications.

The study was also unclear as to whether the booster dose posed the same risk as the initial vaccination.

This can be a pressing issue as many developed countries with heavily vaccinated populations are considering how often they should be given supplemental doses.

However, a French study published on Friday shed some light on the matter.

The study, which has not yet been peer-reviewed or published in a scientific journal, was conducted by Epi-Phare, part of the French drug safety agency ANSM, using data from the health status of millions of French people.

A lower risk of myocarditis has been found with booster doses of Pfizer and Moderna Covid vaccines than with initial vaccination.

“Furthermore, the risk decreases with increasing time between each successive dose,” the researchers say.