MONDAY, Dec. 6, 2021 (HealthDay News) -- It happens very rarely, but most teens and young adults who do experience heart inflammation (myocarditis) after a COVID-19 shot have mild symptoms and recover quickly, new research shows.
â€œOverwhelmingly, data continue to indicate that the benefits of COVID-19 vaccination -- 91% effective at preventing complications of severe COVID-19 infection including hospitalization and death -- far exceed the very rare risks of adverse events, including myocarditis," said Dr. Donald Lloyd-Jones, president of the American Heart Association, who was not involved in the study.
Myocarditis is a rare but serious condition that's most often triggered by an infection and/or inflammation caused by a virus.
The U.S. Centers for Disease Control and Prevention has said there appears to be a link between mRNA COVID-19 vaccines and myocarditis, particularly in people under 39 years of age.
To learn more, researchers analyzed data from 139 12- to 20-year-olds in the United States and Canada who had probable or confirmed myocarditis within a month of receiving a COVID-19 vaccine.
Most were white (66.2%) and male (90.6%). In all, 97.8% of the cases followed an mRNA vaccine, with 91.4% occurring after the second dose.
Symptoms began a median of two days after vaccination -- meaning half started sooner, half later. Chest pain was the most common symptom (99.3%), and fever and shortness of breath occurred in 30.9% and 27.3% of patients, respectively.
About 19% patients ended up in intensive care, but none died. Most patients were hospitalized for two or three days.
More than three-fourths (77.3%) of patients who received a cardiac MRI showed evidence of inflammation or injury to the heart muscle.
Nearly 18.7% initially had at least mildly decreased function in their heartâ€™s left ventricle, but it had returned to normal in the patients who returned for follow-up, according to findings published Dec. 6 in the journal Circulation.
â€œThese data suggest that most cases of suspected COVID-19 vaccine-related myocarditis in people younger than 21 are mild and resolve quickly,â€ said study first author Dr. Dongngan Truong, associate professor of pediatrics at the University of Utah. â€œWe were very happy to see that type of recovery."
She said researchers await further studies to better understand long-term outcomes for patients who have had COVID vaccination-related myocarditis.
"We also need to study the risk factors and mechanisms for this rare complication," Truong said in a journal news release.
She said it is important for health care professionals and the public to have information about the early signs of myocarditis as vaccines become more widely available to children.
â€œStudies to determine long-term outcomes in those who have had myocarditis after COVID-19 vaccination are also planned,â€ Truong added.
The U.S. Centers for Disease Control and Prevention has more on COVID-19 vaccines and heart inflammation.
SOURCE: Circulation, news release, Dec. 6, 2021