Young men are more prone to inflammation of the heart muscle (inflammation of the heart muscle) after the second dose of mRNA vaccines. This is confirmed by a Scandinavian registry study published in the journal JAMA Cardiology.
- Scandinavian research collaboration is crucial to gaining a good understanding of rare side effects, says Geir Bukholm, deputy director of the Norwegian Institute of Public Health (FHI).
FHI participated in a Scandinavian research collaboration that investigated the risk of myocarditis. The study continued for four weeks (28 days) after vaccination against SARS-CoV-2.
It was the early results of this study that prompted FHI to encourage men under the age of 30 to opt for the Pfizer / BioNTech vaccine over the Moderna vaccine. The recommendation was later adapted to also apply to women under 30, in line with the precautionary principle.
The survey is a Scandinavian registry survey that has covered more than 23 million people in Norway, Denmark, Finland and Sweden. In total, there were 1077 cases of myocarditis among vaccinated and unvaccinated subjects during the study period from December 27, 2020 to October 5, 2021.
Increased risk of inflammation of the heart muscle
In men aged 16 to 24 years, researchers found 6 additional cases of myocarditis per 100 vaccinated with the second dose of BioNTech / Pfizer vaccine. Among vaccinated with the second dose of the Moderna vaccine cases of myositis it was 18 out of 100.
The number of additional cases of myocarditis per 100 vaccinations was significantly lower in the older age groups. Among men in all age groups combined, there were 000 extra cases per 0,7 after the second dose of BioNTech / Pfizer. In with the second dose of Modera bywoo 5 additional per 100 after . For women, the corresponding number was 0,1 for BioNTech / Pfizer and 0,5 for Moderna. There were fewer cases after the first dose.
There have been no deaths of people under the age of 40
This Scandinavian study followed patients admitted to hospital with myocarditis. About half have already been released in the first three days. There have been no reports of deaths within 28 days in people under the age of 40.
- Heart complications also occur with Covid-19. Both coronary vaccines have been shown to protect very well against severe Covid-19, says Geir Bukholm.
Complete vaccination data
W In Scandinavian countries we have unique registry data health. In this study, we have almost complete vaccination data from all residents of four Nordic countries (Denmark, Finland, Norway and Sweden). Therefore, we can track hospitalizations due to myocarditis in them.
The results of the study are continuously shared with the Scandinavian immunization programs. They are also shared with other relevant government authorities, such as the Norwegian Medicines Agency (SLV), the European Medicines Agency (EMA) and the World Health Organization (WHO).
The results of the study have already been thoroughly analyzed by the EMA and form part of the knowledge base for its mRNA vaccine recommendations.
We look at their long-term consequences
- The study provided new and important knowledge that directly guides the Norwegian vaccination program, Bukholm adds. However, we still know little about these side effects. That's why we're doing some new research. We look at the long-term consequences after being admitted to hospital for myocarditis. We are also looking at the incidence of myocarditis after the third dose. Additionally, FHI works with communities professional in the clinical observation of these patients in Norway.
Source: National Institute of Public Health
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