The Moderna and Pfizer/BioNTech COVID-19 vaccines are both associated with a “significantly increased” risk of myocarditis and myopericarditis, according to new data published in the BMJ.
However, researchers emphasized, the absolute risk of these complications remains very low, and the clear benefits of vaccination must be taken into consideration.
The study’s authors tracked data from nearly 5 million Danish individuals 12 years old or older who received either the Moderna (mRNA-1273) or Pfizer/BioNTech (BNT162b2) vaccine. All participants were followed for a full year.
Overall, a total of 269 participants developed myocarditis or myopericarditis. While 40% of those patients were between the ages of 12 and 39 years old, 73% of them were male.
Looking closer at the data, the group found that the Moderna vaccine was linked to a heightened risk of myocarditis or myopericarditis, “primarily” among patients in that age group of 12 to 39. The Pfizer/BioNTech vaccine, meanwhile, was only associated with a heightened risk among women.
Also, researchers added, clinical outcomes for these patients were “predominantly mild.”
“Given the worldwide spread of the highly contagious SARS-CoV-2 delta and omicron variants, future infection is the undesirable alternative to vaccination against SARS-CoV-2,” wrote lead author Anders Husby, MD, PhD, of Imperial College London, and colleagues. “Taken together with the potential long-term sequelae of even mild SARS-CoV-2 infection, and with the risk of multisystem inflammatory syndrome among adolescents (which is associated with severe morbidity), our finding of a low absolute risk of myocarditis or myopericarditis with BNT162b2 or mRNA-1273 vaccination supports the overall benefits of such vaccination on an individual, societal, and global level.”
The full study is available here. A similar study was recently published in the American Journal of Cardiology.
Michael has more than 16 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.