TNNI3 and COVID-19: Alizadeh et al. demonstrated that MYO levels were normal, while high-sensitivity troponin levels were increased in a case of myocarditis after COVID-19 vaccination.30 A recent study showed elevated cTnI levels (1,035 ng/L) were suggestive of myocarditis in a 20-year-old male after receiving the second injection of the Pfizer–BioNTech COVID-19 vaccine.