The cumulative threat of myocarditis/myopericarditis amongst international mRNA-1273 recipients
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In a latest examine revealed in Clinical Infectious Diseases, researchers analyzed the incidence of myocarditis amongst coronavirus illness 2019 (COVID-19) messenger ribonucleic acid (mRNA)-1273 vaccinees.

Study: Analysis of Myocarditis Among 252 Million mRNA-1273 Recipients Worldwide. Image Credit: hedgehog94/Shutterstock

Various research have reported a causal affiliation between extreme acute respiratory syndrome coronavirus 2 (SARS-CoV-2) an infection and myocarditis. Moreover, proof exhibits the incidence of myocarditis amongst people vaccinated with the mRNA-1273 COVID-19 vaccine.

About the examine

In the current examine, researchers assessed the cumulative threat of the incidence of myocarditis or myopericarditis amongst people who had obtained the mRNA-1273 COVID-19 vaccine.

The workforce reviewed experiences of potential myopericarditis and myocarditis documented within the Moderna international security database between 18 December 2020 and 15 February 2022. The knowledge collected from this database included hostile occasions reported by people globally. The workforce queried the database for legitimate instances reporting myopericarditis and myocarditis. Available references had been used to develop a scientific strategy that characterised potential experiences of myocarditis after mRNA vaccination and assessed causality.

The Brighton Collaboration case definition for myocarditis was used to categorise particular person instances into 5 classes: (1) stage 1- definitive case, (2) stage 2- possible case, (3) stage 3- doable case, (4) stage 4- a reported occasion with inadequate proof; and (5) stage 5- not a case of myopericarditis or myocarditis primarily based on diagnostic proof and medical findings. The workforce additionally used the World Health Organization–Uppsala Monitoring Centre standardized case causality evaluation device to guage the chance of a case causally related to the vaccine.

The international proportion of mRNA-1273 vaccinees was estimated in keeping with the information retrieved via the Centers for Disease Control and Prevention (CDC), the European CDC, the general public well being company of Canada, the Swiss federal workplace of public well being, and Our World in Data on 16 February 2021. 


The workforce estimated that between 18 December 2020 and 15 February 2022, 568,668,391 doses of the mRNA-1273 COVID-19 vaccine had been administered, and 477,932 particular person instances had been reported, together with 1,819,802 hostile occasions. The particular person instances reported comprised 3027 instances of myopericarditis or myocarditis. Among these, 72% of the instances had been reported by a healthcare skilled concerned within the affected person’s remedy, and 97.5% had critical hostile occasions, together with 1.5% reporting a deadly end result. Almost 21% of the instances reported COVID-19 restoration, whereas 1.6% recovered with sequelae and 25.7% had been recovering.

The workforce famous that 40.3% of the whole instances had been from the European financial space (EEA), 25.2% from the US, 11.5% from Asia, 5.1% from Switzerland, 8.5% from the UK, 8.8% from Canada, and fewer than 1% from the Middle East and Australia. The median age of the examine inhabitants was 29 years, whereas 75% of the instances had been reported in males.

The examine outcomes confirmed that the variety of myopericarditis or myocarditis corresponded to the general reporting fee of 9.23 per 100,000 person-years, regardless of the time of illness onset. The noticed reporting fee amongst people who had obtained the mRNA-1273 vaccine assorted considerably with respect to age and gender.

Furthermore, the reporting fee for males was 14.54 per 100,000 person-years, and for females was 4.11 per 100,000 person-years. Across completely different age teams, the reporting fee was 29.29 per 100,000 person-years amongst people aged between 18 and 24 years. When adjusted in keeping with age and gender, youthful males underneath 40 years had the very best reporting charges for myopericarditis or myocarditis. Overall, the noticed reporting charges for myopericarditis or myocarditis post-mRNA-1273 vaccination resulted in a fee ratio of 1.03.

When the examine was restricted to instances reported inside seven days of a recognized COVID-19 dose, the noticed reporting fee for the vaccinees per 100,000 doses was larger after administering the second vaccine dose. The highest charges reported inside seven days of vaccination had been noticed after the second dose amongst males aged lower than 39 years, particularly these between 18 and 24 years. Comparing the noticed charges to the anticipated charges resulted in a fee ratio of 8.88 for males aged between 18 to 24 years inside seven days of the second vaccine dose. The workforce famous that the charges had been decrease after the third dose than after the second dose.      


Overall, the examine findings confirmed that myopericarditis or myocarditis was a uncommon occasion in mRNA-1273 COVID-19 vaccine recipients. The researchers consider that the advantages of mRNA-1273 vaccination outweigh the potential threat of vaccine-associated myocarditis.     

Journal reference:

  • Straus, W. et al. (2022) “Analysis of Myocarditis Among 252 Million mRNA-1273 Recipients Worldwide”, Clinical Infectious Diseases. doi: 10.1093/cid/ciac446.

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