The risk of heart inflammation (myocarditis or pericarditis) after vaccination against covid-19 virus mRNA vaccine in the British Medical Journal

A study published today in The British Medical Journal (The BMJ) provides more reassuring data on the risk of heart inflammation (myocarditis or pericarditis) after vaccination against the covid-19 virus mRNA vaccine

It confirms the previous report that the risk increases after vaccination with BNT162b2 (Pfizer Biotech) and mRNA-1273 (Moderna), but shows that the absolute number of cases is very low, even in younger age groups, which supports covid-19 mRNA The overall safety of the vaccine provides further evidence

Myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the outer layer of the heart) are rare but serious diseases, usually caused by viral, bacterial or fungal infections

Recent reports and studies have shown that after mRNA vaccination, especially after the second vaccination, the risk of heart inflammation increases

In order to solve this problem, Danish researchers used national healthcare data to search for mRNA vaccination and hospital diagnosis of myocarditis or pericarditis, elevated blood troponin levels (a measure of myocardial damage), and hospital stays of more than 24 hours.

Their analysis included nearly 5 million Danish residents 12 years of age or older who received Pfizer Biotech or Moderna vaccines

Participants were monitored from October 1, 2020 to October 5, 2021, and a series of factors that may have an impact were considered, such as age, gender, vaccine priority groups, and basic health status

During the follow-up period, 269 participants developed myocarditis or pericarditis, of which 108 (40%) were 12-39 years old, and 196 (73%) were men

In general, the results show that there is a strong correlation between Moderna vaccination and myocarditis or pericarditis, while Pfizer Biotechnology vaccination is only related to an increase in the incidence of female myocarditis or myocarditis

Moderna vaccine has a higher incidence of myocarditis or pericarditis than Pfizer Biotech vaccine

For example, among the 3482 295 patients vaccinated with Pfizer Biotechnology vaccine, 48 patients developed myocarditis or pericarditis within 28 days after vaccination (the absolute incidence rate was 1.

Among women, the absolute ratio is 1.

Among the 498,814 individuals vaccinated with Moderna vaccine, 21 individuals developed myocarditis or pericarditis within 28 days after vaccination (absolute incidence rate of 4.

Among women, the absolute ratio is 2 per 100,000 people, while among men it is 6.

Compared with unvaccinated individuals, these two vaccines are also associated with an approximately 50% reduction in the risk of cardiac arrest or death (the most severe manifestation of myocarditis or pericarditis)

In contrast, the risk of cardiac arrest or death 28 days after testing positive for covid-19 is 14 times higher than that of uninfected people

This is an observational study, so the cause cannot be determined.
The researchers pointed out some potential sources of bias, such as increased public awareness of the potential side effects of the vaccine, which may have affected the results
.

However, they said that this is a well-designed study based on high-quality medical data for the entire population.
After further analysis, the results are basically unchanged, indicating that they can withstand close scrutiny
.

Therefore, the researchers concluded that in the Danish population, mRNA vaccination by Moderna and Pfizer-BioNTech is associated with an increased risk of myocarditis or pericarditis, but the absolute incidence of both vaccines after vaccination is very low, even in younger people.
The same is true in the crowd
.

They added that when interpreting these findings, the benefits of vaccination should be considered, and larger multinational studies are needed to further investigate the risk of myocarditis or pericarditis after vaccination in a smaller population
.

(Finish)

Magazine

BMJ

DOI

10.
1136/bmj-2021-068665

Methodological research

Observational research

Subject of research

people

Article title

Study: SARS-CoV-2 vaccination and myocarditis or pericarditis: a population-based cohort study