Myopericarditis; This literature-non-study case was reported in a literature article and describes the occurrence of MYOCARDITIS (Myopericarditis) in a 21-year-old male patient who received mRNA-1273 (Spikevax) for COVID-19 vaccination.       The patient's past medical history included VSD (VSD found at birth which spontaneously resolved and a family history of premature cardiac disease.). Family history included Cardiac disorder NOS.    On an unknown date, the patient received first dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date,  after starting mRNA-1273 (Spikevax), the patient experienced MYOCARDITIS (Myopericarditis) (seriousness criteria hospitalization and medically significant). The patient was treated with COLCHICINE for Myopericarditis, at an unspecified dose and frequency. At the time of the report, MYOCARDITIS (Myopericarditis) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Catheterisation cardiac: revealed disease free coronary arteries revealed disease free coronary arteries. On an unknown date, Echocardiogram: normal (normal) repeat echocardiogram after 3 months was normal and mid-apical wall hypokinesis with preserved ejectio mid-apical wall hypokinesis with preserved ejection fraction.. On an unknown date, Electrocardiogram: diffuse st-elevations (High) Diffuse ST-elevations. On an unknown date, Microbiology test: unrevealing Unrevealing. On an unknown date, Physical examination: abnormal (abnormal) substernal chest pain worse when lying down and improved with leaning forward.. On an unknown date, Troponin: elevated (High) initial troponin was elevated at 27 ng/ml.     The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown.   For mRNA-1273 (Spikevax) (Unknown), the reporter considered MYOCARDITIS (Myopericarditis) to be related.    Concomitant medication was not reported. Patient was presented to the emergency department after experiencing 12 hours of substernal chest pain. Infectious workup, including a tick-borne panel, was unrevealing. The patient was discharged on a regimen of NSAIDs. He had resolution of symptoms at his one-month outpatient follow up visit. Ischemic workup was completed to rule out any previously undiagnosed coronary disease.  Company Comment: This literature non-study case concerns a 21-year-old, male patient with no reported relevant medical history, who experienced the expected, serious (hospitalized, medically significant) AESI Myocarditis (reported as Myopericarditis). The event occurred 5 days after receiving the first dose of mRNA-1273 vaccine, initially presenting with substernal chest pain aggravated while lying down and improved when leaning forward. Persistence of symptoms for 12 hours prompted consult to the emergency department. Troponin level on admission was noted to be elevated (27 ng/mL) and electrocardiography showed diffuse ST elevations highly suggestive of myopericarditis. The patient was worked-up for potential causes including toxic and infectious panel but these were all negative. Cardiac catheterization was performed which revealed normal coronary arteries while echocardiogram showed mid-apical wall hypokinesis with preserved ejection fraction. Course of treatment during hospital stay was not provided in the case. The patient was eventually discharged on a regimen of NSAIDs and colchicine. There was complete resolution of symptom at 1 month of follow-up and, repeat ECG after 3 months was normal. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This literature non-study case concerns a 21-year-old, male patient with no reported relevant medical history, who experienced the expected, serious (hospitalized, medically significant) AESI Myocarditis (reported as Myopericarditis). The event occurred 5 days after receiving the first dose of mRNA-1273 vaccine, initially presenting with substernal chest pain aggravated while lying down and improved when leaning forward. Persistence of symptoms for 12 hours prompted consult to the emergency department. Troponin level on admission was noted to be elevated (27 ng/mL) and electrocardiography showed diffuse ST elevations highly suggestive of myopericarditis. The patient was worked-up for potential causes including toxic and infectious panel but these were all negative. Cardiac catheterization was performed which revealed normal coronary arteries while echocardiogram showed mid-apical wall hypokinesis with preserved ejection fraction. Course of treatment during hospital stay was not provided in the case. The patient was eventually discharged on a regimen of NSAIDs and colchicine. There was complete resolution of symptom at 1 month of follow-up and, repeat ECG after 3 months was normal. The benefit-risk relationship of mRNA-1273 is not affected by this report.