Myocarditis, or heart inflammation, has been considered a rare but serious potential side effect of COVID-19 vaccination, more often after a second dose than after the first, according to the Centers for Disease Control and Prevention.
In a study from Kaiser Permanente, scientists found a third dose of the Moderna or Pfizer COVID-19 vaccine poses no more risk of heart inflammation than a second dose.
They found most cases appeared within seven days of vaccination and the patients recovered.
The findings could help allay concerns about risk going up with each additional dose.
In the study, researchers examined the health records of millions of Southern Californians to see whether third doses of the vaccines, which use mRNA technology to activate the body’s defenses against the coronavirus, were linked to myocarditis, an inflammation of the heart muscle.
Among the more than 3 million members who received the first dose, six people were hospitalized for myocarditis.
Among the 2.9 million who received a second dose, 26 developed myocarditis that required hospitalization – 21 cases of which occurred within seven days.
Among the 1.4 million who received the third dose, nine were hospitalized for myocarditis, with seven of those cases arising within a week.
Compared with what would have been expected in the same population during a one-year period before the pandemic, the team found the incidence of myocarditis was four times greater after the second dose and 2.6 times greater after the third dose.
But overall, myocarditis was rare, most cases were mild, and the symptoms resolved without extensive intervention.
Eight of the nine cases of myocarditis following the third dose were in men, and five in people between 18 and 40 years old.
Previous studies have shown a higher risk of post-vaccine myocarditis in teens and young men.
The team says such risks need to be kept in context, given that other studies have shown the risk of myocarditis is much higher after COVID-19 infection than after vaccination.
In addition to myocarditis, COVID-19 raises the risk of other complications and has killed more than 1 million people in the United States.
If you care about heart health, please read studies about common diabetes drugs that spike heart attack risk, and the best time to take vitamins to prevent heart disease.
For more information about heart health, please see recent studies about common symptoms of heart failure you need to know, and results showing watch for these potential heart problems after COVID-19.
The study was conducted by Dr. Mingsum Lee et al and presented at the American Heart Association’s Scientific Sessions.
Copyright © 2022 Knowridge Science Report. All rights reserved.
