COPENHAGEN (Reuters) – According to a Danish study published in the British Medical Journal late Thursday.
The study, which involved nearly 85% of Danes, or 4.9 million people aged 12 years and older, examined the link between mRNA-based COVID-19 vaccines and heart inflammation, also known as myocarditis or myopericarditis.
Previous studies from Israel and the United States indicated an increased risk of heart inflammation after inoculation with the mRNA vaccines developed by Pfizer-BioNTech and Moderna.
“Vaccination with mRNA-1273 (Moderna’s vaccine) was associated with a significantly increased risk of myocarditis or myopericarditis in the Danish population,” the study said.
However, according to the study, conducted by researchers at the Danish Statens Serum Institute, the overall risk of developing heart inflammation from the vaccines, both of which are based on mRNA technology, was low.
“Overall, the rate of myocarditis or myopericarditis was approximately three to four times higher for mRNA-1273 (Moderna) vaccination than that for BNT162b2 (Pfizer-BioNTech) vaccination,” the study said.
The researchers found only 1 case per 71,400 vaccinated with Pfizer-BioNTech and 1 case per 23,800 vaccinated with Moderna. Most cases had been mild, the study said.
The Pfizer-BioNTech vaccine was only associated with a higher risk of heart inflammation in women, the study said, in contrast to the results of the studies from Israel and the United States.
The authors said the discrepancy could be explained by the average age of the vaccinated population, the time span between the first and second injection, or because fewer Danes had tested positive for COVID-19.
“Our findings generally do not overshadow the many benefits associated with vaccination,” study author Anders Hviid said in a statement.
“One should keep in mind that the alternative to getting an infection with COVID-19 probably also carries a risk of inflammation in the heart muscle,” Hviid said.