Heart is fluttering; High Blood Pressure 191/115 mmHg; having Anxiety episode; Palpitation/ herat Palpitation with elevated pulse; Insomnia/unable to sleep for two days; Loss of appetite; This spontaneous case was reported by a consumer and describes the occurrence of CARDIAC FLUTTER (Heart is fluttering) and HYPERTENSION (High Blood Pressure 191/115 mmHg) in a 20-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 084J21A and 026C21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Penicillin allergy.   On 28-Apr-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 26-May-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 10-Jan-2022, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to 1 dosage form. On 11-Jan-2022, the patient experienced CARDIAC FLUTTER (Heart is fluttering) (seriousness criterion medically significant), HYPERTENSION (High Blood Pressure 191/115 mmHg) (seriousness criterion medically significant), ANXIETY (having Anxiety episode), PALPITATIONS (Palpitation/ herat Palpitation with elevated pulse), INSOMNIA (Insomnia/unable to sleep for two days) and DECREASED APPETITE (Loss of appetite). The patient was treated with PROPRANOLOL (PROPANOLOL [PROPRANOLOL]) for Adverse event, at a dose of 10 milligram twice a day and MELOXICAM for Adverse event, at a dose of 15 milligram once a day. In January 2022, INSOMNIA (Insomnia/unable to sleep for two days) and DECREASED APPETITE (Loss of appetite) had resolved. On 18-Jan-2022, HYPERTENSION (High Blood Pressure 191/115 mmHg) had resolved. At the time of the report, CARDIAC FLUTTER (Heart is fluttering) and PALPITATIONS (Palpitation/ herat Palpitation with elevated pulse) had resolved with sequelae and ANXIETY (having Anxiety episode) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 11-Jan-2022, Blood pressure measurement: high (High) 191/115 mmHg. On 11-Jan-2022, Heart rate: high (High) 95 BPM.     For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered CARDIAC FLUTTER (Heart is fluttering), HYPERTENSION (High Blood Pressure 191/115 mmHg), ANXIETY (having Anxiety episode), PALPITATIONS (Palpitation/ herat Palpitation with elevated pulse), INSOMNIA (Insomnia/unable to sleep for two days) and DECREASED APPETITE (Loss of appetite) to be related.    Reporter stated that patient did not have side effects after the first 2 doses. Patient medical history totally healthy, Never had heart or blood pressure Issues. He never had COVID-Disease and he never had a positive PCR test.  No concomitant medications were reported.  Company comment: This is a spontaneous case concerning a 20 year-old, male patient with no relevant medical history, who experienced the serious, unexpected AESI of cardiac flutter and serious unexpected event of hypertension. The events occurred approximately 36 hours after the booster dose of mRNA-1273 vaccine. The subject also had heart rate of 95 bpm. blood pressure of 191/115 mmHg and palpitations. They were not sure whether it was an anxiety or something else. The patient was unable to sleep and hypertension lasted for a week. The patient also had loss of appetite. The events recovered with sequelae of anxiety attacks. The patient was treated with propranolol and meloxicam  for one week.  The rechallenge was not applicable, as the event occurred after the booster dose. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 31-Jan-2022: significant follow up received. New reporters, Patients demographics, treatment medications and allergy was updated.  New events: loss of appetite and outcome for events were updated.; Sender's Comments: This is a spontaneous case concerning a 20 year-old, male patient with no relevant medical history, who experienced the serious, unexpected AESI of cardiac flutter and serious unexpected event of hypertension. The events occurred approximately 36 hours after the booster dose of mRNA-1273 vaccine. The subject also had heart rate of 95 bpm. blood pressure of 191/115 mmHg and palpitations. They were not sure whether it was an anxiety or something else. The patient was unable to sleep and hypertension lasted for a week. The patient also had loss of appetite. The events recovered with sequelae of anxiety attacks. The patient was treated with propranolol and meloxicam  for one week.  The rechallenge was not applicable, as the event occurred after the booster dose. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.