A recent study has linked COVID-19 vaccinations to heart problems in some male adolescents who received the shots, calling it a “possible rare side effect,” according to the New England Journal of Medicine.

Pfizer and Moderna COVID-19 vaccines have been linked to myocarditis (inflammation of the heart muscle) and pericarditis (inflammation of the outer layer of the heart). Both vaccines utilize the novel messenger RNA (mRNA) technology.

According to an article in the Journal of Pediatrics, among adolescents given a COVID-19 mRNA vaccine, myopericarditis emerged as “an important adverse event.”

The juvenile patients in the study typically experienced chest pain and were found to have elevated serum tropin levels, two biometric markers that indicate heart inflammation, in the period following their vaccination.

The World Health Organization says this condition is also characterized by lymphocytic and monocytic (white blood cell) infiltrates within the muscle layer of the heart, leading to degeneration and death of cells within the heart.The study involved patients treated at Seattle Children’s Hospital between April 1, 2021, and January 7, 2022. All were seen within a week of receiving their second dose of the Pfizer vaccine.

According to the National Organization of Rare Disorders, myocarditis is usually triggered by an infection in the body, either bacterial or viral, and is diagnosed more often in young adult males than in females. The condition generally resolves itself without any additional treatment in about half of those diagnosed, reports the Journal of the American Heart Association.

Of the thirty-five patients in the study who presented symptoms after being vaccinated, only sixteen underwent cardiac imaging in the Seattle study. Some of the remaining patients were treated at different hospitals or excluded from the study for other reasons.

However, eleven of the study’s sixteen participants still displayed cardiac symptoms up to 8 months after their vaccination.

Follow-up imaging performed 3 to 8 months later showed blood flow and cell wall function improvement for most patients. According to researchers, the symptoms were primarily transient. The majority also responded well to treatment, though the study showed persistent abnormal findings.

There is a concern regarding possible longer-term side effects of the vaccine. The researchers, therefore, recommend adequate follow-up to rule out persistent problems.

Due to concerns about elevated rates of heart inflammation among this group, the CDC has changed its guidelines for vaccination. The old guidelines recommended a second vaccination 3 weeks after the first for the Pfizer vaccine and 4 weeks after the first for the Moderna version. In light of the new information, the CDC now recommends a 2-month pause between vaccinations.