Myocarditis; This literature-non-study case was reported in a literature article and describes the occurrence of MYOCARDITIS (Myocarditis) in a  patient of an unknown age and gender who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis.        No Medical History information was reported.   On an unknown date, the patient received second dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Spikevax) (unknown route) dosage was changed to 1 dosage form. On an unknown date,  after starting mRNA-1273 (Spikevax), the patient experienced MYOCARDITIS (Myocarditis) (seriousness criterion medically significant). At the time of the report, MYOCARDITIS (Myocarditis) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, C-reactive protein (Unknown-8 milligram per litre): 11.2 milligram per litre. On an unknown date, Ejection fraction: 61 %. On an unknown date, Electrocardiogram: Sinus bradycardia with premature atrial complexes with aberrant conduction, diffuse ST segment elevation. On an unknown date, Magnetic resonance imaging heart: after 6 days of symptom onset showed myocardial edema and late gadolinium enhancement. On an unknown date, N-terminal prohormone brain natriuretic peptide (Unknown-450 pg/ml): 213 pg/ml. On an unknown date, Troponin T (Unknown-14 ng/L): 1127 ng/L.   For mRNA-1273 (Spikevax) (Unknown), the reporter did not provide any causality assessments.   No Concomitant medications were reported.  4 days after the vaccine patient experienced symptoms of Chest pain, left upper arm pain.  CDC definition myocarditis reported as confirmed. Lake Louise criteria reported as Yes. Free Spike reported as 24.38 pg/mL and total Spike reported as 29.2 pg/mL.  No treatment medications were reported.  This case is for patient from the table.  Company Comment: This is a literature non-study case concerning a patient of unknown age and gender with no reported medical history, who experienced the serious (due to medically significant) expected AESI Myocarditis. The event occurred after 4 days after receiving the second dose of mRNA-1273 vaccine (date of vaccine not reported). The patient experienced symptoms of Chest pain and left upper arm pain. Relevant diagnostic tests performed included a peak C-reactive protein of 11.2 mg/L (upper limit of normal 8 mg/L), ejection fraction of 61 % with no pericardial effusion diagnosed, electrocardiogram showed Sinus bradycardia with premature atrial complexes with aberrant conduction, diffuse ST segment elevation, magnetic resonance imaging of heart showed myocardial edema and Late Gadolinium Enhancement, a peak troponin T of 1127 ng/L (upper limit of normal 14 ng/L) and a peak N-terminal prohormone brain natriuretic peptide of 213 pg/ml (upper limit of normal 450 pg/ml). The diagnosis of myocarditis was confirmed by CDC and Lake Louise criteria. No concomitant and treatment medications were reported. The outcome of the event was reported as unknown. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   This case was linked to US-MODERNATX, INC.-MOD-2023-719589 (Linked Report).; Sender's Comments:  US-MODERNATX, INC.-MOD-2023-719589: