Clinically Suspected Myocarditis Temporally Related to COVID-19 Vaccination in Adolescents and Young Adults: Suspected Myocarditis After COVID-19 Vaccination

Circulation. 2022 Feb;145(5):345-356. doi: 10.1161/CIRCULATIONAHA.121.056583. Epub 2021 Dec 6.


Background: Understanding the clinical course and short-term outcomes of suspected myocarditis after the coronavirus disease 2019 (COVID-19) vaccination has important public health implications in the decision to vaccinate youth.

Methods: We retrospectively collected data on patients <21 years old presenting before July 4, 2021, with suspected myocarditis within 30 days of COVID-19 vaccination. Lake Louise criteria were used for cardiac MRI findings. Myocarditis cases were classified as confirmed or probable on the basis of the Centers for Disease Control and Prevention definitions.

Results: We report on 139 adolescents and young adults with 140 episodes of suspected myocarditis (49 confirmed, 91 probable) at 26 centers. Most patients were male (n=126, 90.6%) and White (n=92, 66.2%); 29 (20.9%) were Hispanic; and the median age was 15.8 years (range, 12.1-20.3; interquartile range [IQR], 14.5-17.0). Suspected myocarditis occurred in 136 patients (97.8%) after the mRNA vaccine, with 131 (94.2%) after the Pfizer-BioNTech vaccine; 128 (91.4%) occurred after the second dose. Symptoms started at a median of 2 days (range, 0-22; IQR, 1-3) after vaccination. The most common symptom was chest pain (99.3%). Patients were treated with nonsteroidal anti-inflammatory drugs (81.3%), intravenous immunoglobulin (21.6%), glucocorticoids (21.6%), colchicine (7.9%), or no anti-inflammatory therapies (8.6%). Twenty-six patients (18.7%) were in the intensive care unit, 2 were treated with inotropic/vasoactive support, and none required extracorporeal membrane oxygenation or died. Median hospital stay was 2 days (range, 0-10; IQR, 2-3). All patients had elevated troponin I (n=111, 8.12 ng/mL; IQR, 3.50-15.90) or T (n=28, 0.61 ng/mL; IQR, 0.25-1.30); 69.8% had abnormal ECGs and arrhythmias (7 with nonsustained ventricular tachycardia); and 18.7% had left ventricular ejection fraction <55% on echocardiogram. Of 97 patients who underwent cardiac MRI at a median 5 days (range, 0-88; IQR, 3-17) from symptom onset, 75 (77.3%) had abnormal findings: 74 (76.3%) had late gadolinium enhancement, 54 (55.7%) had myocardial edema, and 49 (50.5%) met Lake Louise criteria. Among 26 patients with left ventricular ejection fraction <55% on echocardiogram, all with follow-up had normalized function (n=25).

Conclusions: Most cases of suspected COVID-19 vaccine myocarditis occurring in persons <21 years have a mild clinical course with rapid resolution of symptoms. Abnormal findings on cardiac MRI were frequent. Future studies should evaluate risk factors, mechanisms, and long-term outcomes.

Keywords: COVID-19 vaccines; adolescent; myocarditis; young adult.

Publication types

  • Case Reports

MeSH terms

  • Adolescent
  • COVID-19 / prevention & control*
  • COVID-19 Vaccines / adverse effects*
  • Child
  • Electrocardiography / methods
  • Female
  • Humans
  • Magnetic Resonance Imaging, Cine / methods
  • Male
  • Myocarditis / blood
  • Myocarditis / diagnostic imaging*
  • Myocarditis / etiology
  • Myocarditis / physiopathology*
  • Retrospective Studies
  • Time Factors
  • Young Adult


  • COVID-19 Vaccines