heart was fluttering/flutter was really bad; woke up at 3 AM and fainted; had severe chest pain; 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; 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.     Previously administered products included for Product used for unknown indication: COVID-19 VACCINE NRVV AD26. Past adverse reactions to the above products included No adverse event with COVID-19 VACCINE NRVV AD26.    On 03-Dec-2021, the patient received third 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 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), CHEST PAIN (had severe chest pain) 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. In December 2021, 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, CARDIAC FLUTTER (heart was fluttering/flutter was really bad) had not resolved and SYNCOPE (woke up at 3 AM and fainted) and CHEST PAIN (had severe chest pain) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood test: normal (normal) Normal. On an unknown date, Blood thyroid stimulating hormone: normal (normal) Normal. 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. On an unknown date, Laboratory test: normal (normal) Normal. On an unknown date, Metabolic function test: normal (normal) Normal. On an unknown date, Troponin: normal (normal) Normal.         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 with the non-serious unexpected events of Inappropriate schedule of vaccine administered, Chest discomfort, and Chest pain. On 03-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine). The event of Inappropriate schedule of vaccine administered occurred on the same day, with all other events occurring on the following day. The rechallenge was unknown since there's no information about the first two doses. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report; 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 with the non-serious unexpected events of Inappropriate schedule of vaccine administered, Chest discomfort, and Chest pain.On 03-Dec-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine). The event of Inappropriate schedule of vaccine administered occurred on the same day, with all other events occurring on the following day. The rechallenge was unknown since there's no information about the first two doses. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report