Risk of Myocarditis in Adolescent Population Linked to COVID-19 Vaccination

August 11, 2021
Connor Iapoce

Connor Iapoce is an assistant editor for HCPLive and joined the MJH Life Sciences team in April 2021. He graduated from The College of New Jersey with a degree in Journalism and Professional Writing. He enjoys listening to records, going to concerts, and playing with his cat Squish. You can reach him at ciapoce@mjhlifesciences.com.

Investigators believe benefit of COVID-19 vaccination outweigh the risk of myocarditis in adolescent population.

Although initial reports have determined the BNT162b2 (Pfizer-BioNTech) COVID-19 vaccine to be well-tolerated without serious adverse events, cases of myocarditis have been reported since the Emergency Use Approval in May 2021.

A recent study outlined the occurrence of myocarditis in an adolescent population younger than 19 years, who were hospitalized with myocarditis within 30 days of receiving the vaccine.

A team of investigators, led by Audrey Dionne, MD, Department of Cardiology, Boston Children's Hospital, found myocarditis was most commonly diagnosed in boys after the second dose with a mild short-term course, but long-term risks of post-vaccination myocarditis remain unknown.

Study Methods

The case series study included all patients ≤19 years old with acute myocarditis after COVID-19 vaccination at a single-center, pediatric referral facility with admissions between May - July 2021.

Investigators defined myocarditis as chest pain and elevated troponin levels in the absence of an alternate diagnosis.

Demographics including race and ethnicity were self-reported according to United States Census categories, due to known association with COVID-19 related illness.

The team defined elevated troponin T level as ≥0.01 ng/mL. In addition, all patients underwent cardiac evaluation, including electrocardiogram, echocardiogram, and cardiac magnetic resonance imaging.


A total of 15 patients were admitted for the management of myocarditis after COVID-19 vaccination between May - July 2021. The team noted symptoms manifested after the second dose in all cases, but 1 in the study.

Patients had a median age of 15 years old, with the majority of patients male (93%) and self-identified non-Hispanic White (n = 8) followed by Hispanic White (n = 2), other Hispanic (n = 1) other non-Hispanic (n = 1), and unknown (n = 3).

Data show chest pain occurred in all 15 patients, with a median of 3 days. Further, investigators observed fever in 10 patients (67%), myalgia in 8 patients (53%), and headache in 6 patients (40%).

In addition, troponin levels were found elevated in all patients at admission, with a median of 0.25 ng/mL and peaked 0.1 to 2.3 days following admission.

In an echocardiogram examination, a total of 3 patients (20%) had decreased left ventricular ejection fraction. In 5 patients (33%), the team observed abnormal global longitudinal or circumferential strain.

Investigators also observed cardiac magnetic resonance imaging findings showed consistency with myocarditis in 13 patients (87%).

Data show this included late gadolinium enhancement in 12 patients (80%), regional hyperintensity on T2-weighted imaging in 2 patients (13%), elevated extracellular volume fraction in 3 patients (20%), and elevated LV global native T1 in 2 patients (20%).

They noted no patient required ICU admission, with a median hospital length of stay of 2 days. In follow-up of 1 - 13 days after hospital discharge, 11 patients (73%) showed resolution of symptoms. However, 1 patient had persistent borderline low LV systolic function on echocardiogram, while troponin levels remained mildly elevated in 3 patients.


Investigators concluded that although vaccine-related myocarditis was generally uncomplicated and short-term, there is uncertainty about the long-term prognosis.

However, they noted that despite the risk of myocarditis, the benefits of vaccination likely outweigh the risks in adolescents and children.

“It is estimated that COVID-19 vaccination in males aged 12 to 29 years can prevent 11 000 COVID-19 cases, 560 hospitalizations, 138 intensive care unit admissions, and 6 deaths compared with 39 to 47 expected myocarditis cases,” investigators wrote.

The study, “Association of Myocarditis With BNT162b2 Messenger RNA COVID-19 Vaccine in a Case Series of Children,” was published in JAMA Cardiology.