Myocarditis after corona vaccination: how dangerous is Moderna for younger people?

Heart muscle inflammation after an mRNA vaccination is extremely rare, but it occurs mainly in young people. A Scandinavian study claims to have found out that the risk with the Moderna vaccine is higher than with Biontech. Several countries are drawing conclusions from this. But what do the German numbers say?

The mRNA vaccines from Biontech and Moderna are considered premium vaccines in the fight against the corona pandemic. This is mainly due to the good tolerance and high effectiveness. But already at the end of April it was noticed in Israel for the first time that after a corona vaccination with Biontech, heart muscle inflammation occurred in some vaccinated people. Young men between the ages of 16 and 30 are particularly affected. Investigations in the USA in August confirm the reports and also state: Moderna vaccinations are also linked to myocarditis.

Even though both studies confirm that the risk of developing myocarditis after an mRNA vaccination is extremely low, Sweden, Finland and Denmark now want to play it safe – and are restricting the use of the Moderna vaccine. In Sweden and Finland, the US manufacturer’s vaccine will not be administered to anyone under the age of 30 for the time being, and in Denmark to anyone under 18.

Why are Sweden, Finland and Denmark only restricting the use of Moderna?

All three countries stressed that this was a purely precautionary measure. Recent data indicated an increase in heart muscle and pericardial inflammation in adolescents and young adults after vaccination, said the Swedish health authority Folkhälsomyndigheten. “The link is particularly clear when it comes to Moderna’s Spikevax vaccine, especially after the second dose.”

The Finnish government announced that it is based on a Scandinavian study to be published in the next few weeks. At the end of last week the Health Authority in Canada after analyzing the data, explains that vaccinations with Moderna led to more cases of heart inflammation than those with Biontech. These are more common in adolescents and adults under 30 years of age and more common in men. However, the majority of those affected only fell ill relatively easily and recovered quickly, according to the authority.

For Sweden and Finland, this is reason enough to pause the vaccinations with Moderna for all under 30-year-olds. The affected age group should instead receive the vaccine from Biontech / Pfizer – also as a second vaccination, recommended the health authorities of the countries. Denmark is taking a less drastic step and for the time being is stopping Moderna vaccinations only for adolescents and children under 18 years of age. The Danish government emphasized that the assessment continues that the Moderna preparation is a particularly effective vaccine that has an important place in the country’s vaccination campaign.

What do the data from Germany say?

Cases of myocarditis after mRNA vaccinations are also known in Germany. And here, too, it is conspicuous: “Apparently young men in particular are affected after the second vaccination,” writes the Paul Ehrlich Institute (PEI) in its latest safety report. However, if you look at the current figures, there is only a minimal difference between Biontech and Moderna: On average, after 100,000 Moderna vaccinations, 4.60 cases of myocarditis in the age group 18 to 29 were reported, at Biontech it was 4.28. In all older age groups, the reporting rate is between 1.74 and 0.12.

What is the risk of myocarditis after vaccination with Biontech?

One current Israeli study studied the risk of myocarditis in people vaccinated with Biontech versus the risk in unvaccinated people. The result: The scientists found a more than three-fold increased risk in the vaccinated people. On average, there were 2.7 additional cases of myocarditis per 100,000 people in the group of those vaccinated with Biontech. However, the study did not evaluate the age and gender of those affected.

Is it safer not to have a vaccination?

No. Because a Sars-CoV-2 infection carries a significantly higher risk of myocarditis than a corona vaccination. According to Analyzes by US researchers infected people have a 15 times higher risk of developing myocarditis than healthy people. In addition, depending on the age group, serious consequences such as cardiac arrhythmias, venous thrombosis or pulmonary embolism are much more likely.

What is myocarditis?

In myocarditis, cells in the muscle tissue of the heart become inflamed. The cause is often an infection with bacteria or viruses. It occurs particularly frequently after the flu has been dragged on. Although the disease usually heals again, some people affected can experience long-term damage such as permanent heart failure. In rare cases, myocarditis can also have a non-infectious cause, according to the German Heart Foundation. A possible explanation for this could be autoimmune diseases.

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Why are young people more likely to be affected?

It is still unclear why younger people can experience cardiac disorders after vaccination. Apparently, the problem does not only affect mRNA and other corona vaccines. An earlier one Analysis of the “Vaccine Adverse Event Reporting System” of the FDA in the “International Journal of Cardiology” had shown that the complication was reported even after vaccinations against human papillomavirus, influenza, meningococcal, typhoid, Japanese encephalitis, and anthrax. It was particularly common after a smallpox vaccination with a rate of 71.88 cases per 100,000 vaccinations. Here, too, younger people were more likely to be affected, although not as conspicuously often as with the corona vaccines.