Myocarditis Following a COVID-19 Messenger RNA Vaccination: A Japanese Case Series

Intern Med. 2022 Feb 15;61(4):501-505. doi: 10.2169/internalmedicine.8731-21. Epub 2021 Nov 27.


COVID-19 vaccine-related myocarditis has been reported worldwide. We herein report two Japanese cases with suspected vaccine-related myocarditis. A 27-year-old man was admitted with chest pain 4 days after the second vaccination. An electrocardiogram (ECG) did not reveal any significant abnormalities. The second patient, a 37-year-old man, was admitted with chest pain 9 days after the first vaccination. His ECG exhibited ST-elevation in multiple leads. In both cases, cardiac magnetic resonance imaging findings were consistent with myocarditis. They recovered with symptomatic relief within a few days. These cases suggest that the benefit of COVID-19 vaccination exceeds the risk of vaccine-related myocarditis.

Keywords: COVID-19 vaccination; coronavirus; myocarditis.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • COVID-19 Vaccines
  • COVID-19*
  • Humans
  • Japan
  • Male
  • Myocarditis* / chemically induced
  • Myocarditis* / diagnosis
  • RNA, Messenger
  • SARS-CoV-2
  • Vaccination / adverse effects


  • COVID-19 Vaccines
  • RNA, Messenger