Response to: Note the distinction between myocarditis, novel coronavirus myocarditis and COVID-19 vaccine-associated myocarditis.

Abstract

We are delighted that Dr Xianqiang has written to us with a comment on our article about myocarditis after coronavirus disease 2019 (COVID-19) messenger RNA (mRNA) vaccines. 1 It has recently been reported that myocarditis can be caused by COVID-19 and COVID-19 mRNA vaccines. 1,2 As Dr Yu stated, COVID-19 vaccine-associated myocarditis has a different clinical course and mechanism compared to COVID-19 myocarditis. Suspected cases of vaccine-associated myocarditis are characterized by onset within 2 weeks of vaccination in healthy young men. The cases of histologically confirmed fulminant myocarditis after COVID-19 mRNA vaccines show an inflamma-tory infiltrate predominantly composed of T-cells, macro-phages, eosinophils, B cells and plasma cells, 3 which is suggested to be associated with autoimmunity and allergies. It is important to distinguish between these two clinical entities. From the clinical perspective of vaccine-associated myocarditis, young men often show an early repolarization pattern on elec-trocardiograms (ECGs), making it difficult to diagnose accurate-ly. Transthoracic echocardiogram (TTE) showed no remarkable findings in our cases. Therefore, we emphasize that the diagnosis of myocarditis requires multimodality, including high-sensitivity troponin, serial ECGs, global longitudinal strain with