Scientists have traced the link between coronavirus vaccination and inflammation of the heart muscle in 42 million people over the age of 13.
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New studies by British scientists show a link between vaccination against COVID-19 and the development of acute myocarditis. Prior to this, several countries had reported the influence of messenger RNA (mRNA) BNT162b2 (this is a vaccine from Pfizer) on the development of this disease. In addition, an increase in hospitalizations or deaths due to myocarditis has been reported after both mRNA and vector vaccines.
But at the same time, for the entire vaccinated population in the same England, the risk of myocarditis after vaccination was small compared to the same risk after a positive test for coronavirus and at the same time severe acute respiratory syndrome. Therefore, it was important for scientists to assess the risks of developing myocarditis after the introduction of various coronavirus vaccines, especially after the third dose, since revaccination programs are being implemented at the international level to combat the micron strain.
The study, published on medRxiv, was conducted on a sample of more than 42 million people over the age of 13 who received the third dose of the vaccine. It ran from December 1, 2020 to November 15, 2021. The scientists used the NHS Immunization Management Service (NIMS) to collect information about people. To determine the association between the first, second, or third dose of ChAdOx1 (AstraZeneca), BNT162b2 (Pfizer), mRNA-1273 (Moderna), or SARS-CoV-2 infection with myocarditis, individual patient data were compared with national data.
In the study, 13.5% of people tested positive for SARS-CoV-2 after receiving the first dose of the vaccine, 30.9% after receiving the second dose, and 0.9% after receiving the third dose. The percentage of people hospitalized or dying due to myocarditis during the study period was 0.006%, of which 0.001% were affected within 1-28 days of any dose of vaccine.
The study found that the risk of death or hospitalizations for myocarditis are higher after the first and second doses of vaccination. In contrast, after the third dose of vaccination, the risk is significantly lower. Moreover, compared to adenovirus (vector) vaccines, mRNA vaccines carry a higher risk. The experts also found that the risk of myocarditis is higher in men under the age of 40 than in women of the same age group.
It is important to note that this study is still awaiting evaluation and review by the scientific community. Previously, the effect of vaccination on the development of myocarditis in young men aged 12-17 was also studied. According to this study, the risk of inflammation of the heart muscle in boys is six times higher after suffering from coronavirus than after vaccination.