Epidemiologist Professor Rickard Ljung of the Swedish Medical Products Agency studied health data on a total of some 23.1 million people from Denmark, Finland, Norway, and Sweden from late December 2020 to early October 2021.
The team identified 1,077 cases of myocarditis and 1,149 of pericarditis.
Examining those subjects who had been jabbed, the team found that the likelihood of developing myocarditis was higher following a second dose of the mRNA vaccine.
Specifically, the risk increased by 75 percent with BioNTech/Pfizer and 557 percent with Moderna.
Moreover, the team found that myocarditis risk following two jabs was highest for young men between 16-24 years of age.