Acute myocarditis; Substernal chest pain; Chill; fever; This literature-non-study case was reported in a literature article and describes the occurrence of MYOCARDITIS (Acute myocarditis), CHEST PAIN (Substernal chest pain), CHILLS (Chill) and PYREXIA (fever) in a 25-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination.   LITERATURE REFERENCE: Acute myocarditis after a second dose of the mRNA COVID-19 vaccine: a report of two cases. Clinical Imaging. 2021;78:247-49     No Medical History information was reported.   On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On an unknown date, received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On an unknown date, the patient experienced MYOCARDITIS (Acute myocarditis) (seriousness criteria hospitalization and medically significant), CHEST PAIN (Substernal chest pain) (seriousness criterion hospitalization), CHILLS (Chill) (seriousness criterion hospitalization) and PYREXIA (fever) (seriousness criterion hospitalization). The patient was hospitalized from sometime in 2021 to sometime in 2021 due to MYOCARDITIS, then for 3 days due to CHEST PAIN, CHILLS and PYREXIA. At the time of the report, MYOCARDITIS (Acute myocarditis), CHEST PAIN (Substernal chest pain), CHILLS (Chill) and PYREXIA (fever) was resolving.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In 2021, Angiogram: normal (normal) normal coronary arteries. In 2021, Blood pressure measurement: borderline (Borderline) 129/75 mmHg. In 2021, Body temperature: high (High) 39.1 degree celcius. In 2021, C-reactive protein (0-0.5): high (High) 25 ng/ml. In 2021, Echocardiogram: normal (normal) normal function and no significant valvular disease; ejection fraction was 55%. In 2021, Electrocardiogram: abnormal (abnormal) mild conclave ST elevation with no reciprocal changes. In 2021, Heart rate: normal (normal) 76 bpm. In 2021, Magnetic resonance imaging: abnormal (abnormal) normal left ventricular function, , subepicardial late gadolinium enhancement in the anterolateral wall of the mid and apical left ventricle, increased T1 (1450-1550 ms), T2 significant intensity (54-60 ms). In 2021, Oxygen saturation: normal (normal) 98%. In 2021, Red blood cell sedimentation rate (0-15): high (High) 25 mm/h. In 2021, Respiratory rate: normal (normal) 20. In 2021, Respiratory viral panel: negative (Negative) negative. In 2021, SARS-CoV-2 test: negative (Negative) negative (1 of 1) and negative (Negative) negative (2 of 2). In 2021, Troponin I (0-0.032): elevated (High) 14 ng/ml, elevated (High) 20.4 ng/ml on hospital day 2 and elevated (High) declined to 9.5 ng/ml on the morning of hospital day 3.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered MYOCARDITIS (Acute myocarditis) to be possibly related. No further causality assessments were provided for CHEST PAIN (Substernal chest pain), CHILLS (Chill) and PYREXIA (fever).    Concomitant product use was not provided. Treatment information was not provided.  Based on the current available information and temporal association between the use of the product, and the start date of the events, a causal relationship cannot be excluded.   This case was linked to MOD-2021-241512 (Patient Link).   Most recent FOLLOW-UP information incorporated above includes: On 29-Jun-2021: Follow up received by safety 30-Jun-2021 included an email with FTA.  NNI; Sender's Comments: Based on the current available information and temporal association between the use of the product, and the start date of the events, a causal relationship cannot be excluded.