This literature-non-study case was reported in a literature article and describes the occurrence of PERICARDIAL HAEMORRHAGE (Hemorrhagic pericardial effusion) in a 67-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 vaccination. LITERATURE REFERENCE: A case of idiopathic hemorrhagic pericardial effusion: no clues left behind. 2022;79 (9): 2694. Concurrent medical conditions included Hypothyroidism. On an unknown date, the patient received dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, after starting mRNA-1273 (Spikevax), the patient experienced PERICARDIAL HAEMORRHAGE (Hemorrhagic pericardial effusion) (seriousness criteria hospitalization and medically significant). The patient was treated with COLCHICINE for Adverse event, at an unspecified dose and frequency and IBUPROFEN for Adverse event, at an unspecified dose and frequency. At the time of the report, PERICARDIAL HAEMORRHAGE (Hemorrhagic pericardial effusion) had resolved. DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Antibody test: negative (Negative) as a part of rheumatologic workup was negative. On an unknown date, C-reactive protein: 93.80 mg/l 93.80 mg/L. On an unknown date, Echocardiogram: showed ejection fraction of 55-60% showed ejection fraction of 55-60% and large pericardial effusion with tamponade physiology. On an unknown date, Electrocardiogram: was suggestive of sinus tachycardia ECG was suggestive of sinus tachycardia. On an unknown date, Haemoglobin: 9.6 g/dl 9.6 g/dl. On an unknown date, Heart rate: 136/min 136/min. On an unknown date, Physical examination: muffled heart sounds Muffled heart sounds. On an unknown date, SARS-CoV-2 test: negative (Negative) Negative. The action taken with mRNA-1273 (Spikevax) (Unknown) was unknown. For mRNA-1273 (Spikevax) (Unknown), the reporter considered PERICARDIAL HAEMORRHAGE (Hemorrhagic pericardial effusion) to be related. No concomitant medications were reported. The patient with a history of hypothyroidism presented with dyspnea, chest discomfort, chills since 2 weeks. She had received mRNA-1273 vaccine 7 days prior to presentation. Vitals were notable for a heart rate of 136/min, otherwise she was hemodynamically stable. Physical exam was notable for muffled heart sounds. Emergent pericardiocentesis was done, removing 940 mL of sanguineous fluid. Pericardial fluid showed predominantly red blood cells; cytology was negative for malignant cells. She remained hemodynamically stable and was discharged on colchicine and ibuprofen. The patient did well on follow up at one month. Company Comment: This is a literature non-study case concerning a 67-year-old female patient with no relevant medical history, who was hospitalized due to the unexpected, serious (medically significant) event of Pericardial haemorrhage (reported as Hemorrhagic pericardial effusion), 7 days after receiving a dose of mRNA-1273 vaccine. Date of vaccination was not specified. The patient presented with dyspnea, chest discomfort and chills. On unknown date, upon Physical examination the patient had muffled heart sounds, Echocardiogram showed ejection fraction of 55-60% and large pericardial effusion with tamponade physiology, Electrocardiogram was suggestive of sinus tachycardia with Heart rate of 136/min. Emergent pericardiocentesis was done, removing 940mL of sanguineous fluid. Pericardial fluid showed predominantly red blood cells and Cytology was negative for malignant cells. Discharged medications were Colchicine and Ibuprofen. At the time of reporting, the event had resolved. The benefit-risk relationship of mRNA-1273 is not affected by this report. Sender's Comments: This is a literature non-study case concerning a 67-year-old female patient with no relevant medical history, who was hospitalized due to the unexpected, serious (medically significant) event of Pericardial haemorrhage (reported as Hemorrhagic pericardial effusion), 7 days after receiving a dose of mRNA-1273 vaccine. Date of vaccination was not specified. The patient presented with dyspnea, chest discomfort and chills. On unknown date, upon Physical examination the patient had muffled heart sounds, Echocardiogram showed ejection fraction of 55-60% and large pericardial effusion with tamponade physiology, Electrocardiogram was suggestive of sinus tachycardia with Heart rate of 136/min. Emergent pericardiocentesis was done, removing 940mL of sanguineous fluid. Pericardial fluid showed predominantly red blood cells and Cytology was negative for malignant cells. Discharged medications were Colchicine and Ibuprofen. At the time of reporting, the event had resolved. The benefit-risk relationship of mRNA-1273 is not affected by this report.