heart was fluttering/flutter was really bad; woke up at 3 AM and fainted; like a pressure/ felt like there was a lot of pressure in her chest/ She felt like someone had their knee right in the center of her chest, between her breasts; had severe chest pain; sweating; Inappropriate schedule of vaccine administered; This spontaneous case was reported by a consumer and describes the occurrence of CARDIAC FLUTTER (heart was fluttering/flutter was really bad) and SYNCOPE (woke up at 3 AM and fainted) in a 61-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 029H21B) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Anaphylaxis, Hives and Hay fever. Previously administered products included for Product used for unknown indication: COVID-19 VACCINE NRVV AD26 (Time: 10:00 AM; Lot/Batch: 206A21A; Route and body site: Left arm) on 19-Jun-2021. Past adverse reactions to the above products included No adverse event with COVID-19 VACCINE NRVV AD26. Concurrent medical conditions included Fruit allergy (anaphylaxcic shock, swelling, difficulty breathing, hives) since 12-Apr-1998.    On 03-Dec-2021 at 11:30 AM, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 03-Dec-2021, the patient experienced INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Inappropriate schedule of vaccine administered). On 04-Dec-2021, the patient experienced CHEST PAIN (had severe chest pain). 04-Dec-2021, the patient experienced HYPERHIDROSIS (sweating). On 04-Dec-2021 at 3:00 AM, the patient experienced CARDIAC FLUTTER (heart was fluttering/flutter was really bad) (seriousness criterion medically significant), SYNCOPE (woke up at 3 AM and fainted) (seriousness criterion medically significant) and CHEST DISCOMFORT (like a pressure/ felt like there was a lot of pressure in her chest/ She felt like someone had their knee right in the center of her chest, between her breasts). On 03-Dec-2021, INAPPROPRIATE SCHEDULE OF PRODUCT ADMINISTRATION (Inappropriate schedule of vaccine administered) had resolved. On 04-Jan-2022 at 1:00 PM, CARDIAC FLUTTER (heart was fluttering/flutter was really bad), SYNCOPE (woke up at 3 AM and fainted) and CHEST DISCOMFORT (like a pressure/ felt like there was a lot of pressure in her chest/ She felt like someone had their knee right in the center of her chest, between her breasts) had resolved. At the time of the report, CHEST PAIN (had severe chest pain) and HYPERHIDROSIS (sweating) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood pressure measurement: 138/80 (High) 138/80. On an unknown date, Blood test: normal (normal) Normal. On an unknown date, Blood thyroid stimulating hormone: normal (normal) Normal. On an unknown date, Body temperature: 98 degrees f (normal) 98 degrees f. On an unknown date, Chest X-ray: normal (normal) Normal. On an unknown date, Electrocardiogram: normal (normal) Normal. On an unknown date, Full blood count: normal (normal) Normal. On an unknown date, Heart rate: abnormal (abnormal) heart is beating really hard/rapid heart beat and 76 (normal) 76. On an unknown date, Laboratory test: 19 (normal) 19 and normal (normal) Normal. On an unknown date, Metabolic function test: normal (normal) Normal. On an unknown date, Oxygen saturation: 97 % (normal) 97 %. On an unknown date, Troponin: normal (normal) Normal.         Symptoms experienced by the patient reported as irregular heart rate/palpitations, heart rate greater than 100 beats per min, chest tightness, decreased level of consciousness, feeling hot. Event cause the patient to seek medical care. Patient was on emergency room/department from 18-Dec-2021 to 19-Dec-2021.  No concomitant medication information was provided. No treatment medication was provided.  Company Comment - This is a spontaneous case concerning a 61-year-old female patient with no relevant medical history provided, who experienced the serious and unexpected event of cardiac flutter and the expected event of syncope. On 03-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine). The events occurred 1 day after the second dose of mRNA-1273 vaccine, and had resolved on the same day. The rechallenge was unknown. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 04-Jan-2022: Follow-up information was received and had no new information. On 15-Jan-2022: Follow up received as medical history, lab data and event added.; Sender's Comments: This is a spontaneous case concerning a 61-year-old female patient with no relevant medical history provided, who experienced the serious and unexpected event of cardiac flutter and the expected event of syncope. On 03-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine). The events occurred 1 day after the second dose of mRNA-1273 vaccine, and had resolved on the same day. The rechallenge was unknown. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.