Myocarditis-induced Sudden Death after BNT162b2 mRNA COVID-19 Vaccination in Korea: Case Report Focusing on Histopathological Findings

Abstract

We present autopsy findings of a 22-year-old man who developed chest pain 5 days after the first dose of the BNT162b2 mRNA vaccine and died 7 hours later. Histological examination of the heart revealed isolated atrial myocarditis, with neutrophil and histiocyte predominance. Immunohistochemical C4d staining revealed scattered single-cell necrosis of myocytes which was not accompanied by inflammatory infiltrates. Extensive contraction band necrosis was observed in the atria and ventricles. There was no evidence of microthrombosis or infection in the heart and other organs. The primary cause of death was determined to be myocarditis, causally-associated with the BNT162b2 vaccine.

Keywords: Adverse Event Following Immunization; Coronavirus Disease 19; Myocarditis; Sudden Cardiac Death; Vaccination; mRNA Vaccines.

Fig. 1. Histopathology of the heart. (A) Hematoxylin and eosin stains of atrial septum shows massive inflammatory infiltration with neutrophil predominance. (B) The myocytes often show contraction band necrosis (yellow arrows), which were highlighted by Masson's trichrome staining. (C) The atrioventricular node area shows extension of atrial myocarditis to the superficial layer of the node. (D) The ventricular myocardium is free of inflammatory infiltrates, but there are multiple large foci of contraction band necrosis (yellow arrows) particularly in the left ventricular wall and the ventricular septum. Bars represent 100 µm. The blue arrows in insets show where the section was taken from the low magnification views. Hematoxylin and eosin stain was used for the specimen shown in (A) and Masson's trichrome stain was used for the specimen shown in (B-D).

RA = right atrium, LA = left atrium, RV = right ventricle, LV = left ventricle.

Fig. 2. Immunohistochemistry of the heart. (A) Immunohistochemical staining for CD68 shows that most of the inflammatory cells are histiocytes. (B) Most of the inflammatory cells are negative for CD3 staining, indicating a paucity of lymphocytes. (C) Positive staining for C4d shows scattered single-cell necrosis of atrial myocytes. Bars represent 100 µm.