Myocarditis after Pfizer and Moderna mRNA technology based gene injection vaccine (Larson et al.); describes 8 patients who were hospitalized with chest pain and who were diagnosed with myocarditis

by Paul Alexander

by laboratory and cardiac magnetic resonance imaging within 2 to 4 days of receiving either the Pfizer BNT162b2 or Moderna mRNA-1273 vaccine

‘All individuals were otherwise healthy males between the ages of 21 and 56 years. All but 1 patient developed symptoms after their second dose. Systemic symptoms began within 24 hours after vaccine administration in 5 out of 8 patients, with chest pain presenting between 48 and 96 hours later. Chest pain was most commonly described as constant, nonpositional, and nonpleuritic (only patient 7 reported pericardial pain), consistent with acute myocarditis mainly without pericardial involvement. Troponin values were elevated in all individuals and appeared to peak the day after admission, whereas no patient had eosinophilia.

All patients were tested and were negative for SARS-CoV-2. Left ventricular ejection fraction was reduced (<50%) in 2 of 8 (25%) patients with a median left ventricular ejection fraction of 51.5% (first to third quartile, 48% to 59%). Five patients demonstrated regional wall motion abnormalities with inferior and inferolateral walls involved, and the remaining 3 cases had generalized hypokinesis. Some patients were tachycardic at presentation, but no patients required inotropes or mechanical circulatory support.



‘The patients presented here demonstrated typical signs, symptoms, and diagnostic features of acute myocarditis. The temporal association between receiving an mRNA-based COVID-19 vaccine and the development of myocarditis is notable.

Trials that tested the BNT162b2 and mRNA-1273 vaccines showed that systemic reactogenicity more often occurred after dose 2 and generally within 48 hours after vaccination.1,2 On average, our patients presented with symptoms of acute myocarditis 3 days after the second injection, and in 5 out of 8 patients fever appeared a day before, supporting the hypothesis that myocarditis could be an mRNA vaccine–related adverse reaction. The only patient who experienced myocarditis after the first vaccination had a previous SARS-CoV-2 infection.’