A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster; A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster; This spontaneous case was reported by a patient and describes the occurrence of the first episode of ATRIAL FIBRILLATION (A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster) and the second episode of ATRIAL FIBRILLATION (A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster) in a 74-year-old male patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (batch no. AS7164B) for COVID-19 prophylaxis.    Co-suspect product included non-company product INFLUENZA VACCINE (FLU VACCINE VII) for an unknown indication.    Concurrent medical conditions included Blood pressure high. Concomitant products included CARVEDILOL, LOSARTAN and AMLODIPINE for Blood pressure high.   On 06-Oct-2022, the patient received fifth dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) 1 dosage form and dose of INFLUENZA VACCINE (FLU VACCINE VII) (unknown route) 1 dosage form. On 06-Oct-2022 at 6:00 PM, the patient experienced the first episode of ATRIAL FIBRILLATION (A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster) (seriousness criterion medically significant). On an unknown date, the patient experienced the second episode of ATRIAL FIBRILLATION (A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster) (seriousness criterion medically significant). The patient was treated with APIXABAN (ELIQUIS) at an unspecified dose and frequency. At the time of the report, last episode of ATRIAL FIBRILLATION (A-Fib after Bivalent Booster/2nd A-fib since received a combination of Bivalent Booster) had not resolved.            It was reported that patient received 5 shots of Moderna COVID-19 vaccine. Shot 1: First Primary monovalent dose on 04-FEB-2021 (Lot number- 026L20A & Exp. Date: unknown). Shot 2: 2nd Primary monovalent dose on 04-MAR-2021 (Lot number- 013A21A & Exp. Date: unknown). Shot 3: First Monovalent Booster dose on 27-OCT-2021 (Lot number-  003F21A & Exp. Date unknown). Shot 4: 2nd Monovalent Booster dose on 20-APR-2022 (Lot number- 005M21A & Exp. Date: unknown). Patient had bivalent and Flu shot at the same time (12 noon)  in different arms. It was reported that on 6-oct-2022 at 6 PM his apple watch notified him that he had atrial fibrillation. He called his Cardiologist who told him to go to the emergency room. He visited the ER and they started him on Eliquis. He was fine after that. He had second atrial fibrillation on Nov-2022 since then the doctor had some procedures that will be done in Dec-2022. He stated that he saw on the internet and some friends also had Atrial fibrillation after receiving the Bivalent booster. He is not sure if there was any mention of Myocarditis or Pericarditis. He is not sure if those other people had a Flu vaccine and the Bivalent Booster at the same time. His doctor did not mention anything about Myocarditis. They only spoke about Atrial fibrillation.    Company Comment :This spontaneous case concerns a 74  year old male with hypertension who experienced the unexpected, serious (medically significant) adverse event of special interest Atrial fibrillation a few hours after receiving a dose of mRNA1273 bivalent BA .4/5 as fifth dose in the COVID-19 vaccine series. The patient experienced sudden onset atrial fibrillation post vaccination notified to him by a device. He was advised by his cardiologist to visit the emergency department for evaluation. The patient was started on eliquis and was eventually discharged. The patient had another episode of atrial fibrillation approximately a month after the initial incident and was scheduled for ancillary procedures the next month.  Further details on the clinical course and additional treatment were not provided. The patient's advanced age and concurrent hypertension may be considered as risk factors for atrial fibrillation. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event seriousness assessed as per medical judgment.    This case was linked to US-MODERNATX, INC.-MOD-2022-673920, US-MODERNATX, INC.-MOD-2022-673920 (Linked Report).; Sender's Comments: This spontaneous case concerns a 74  year old male with hypertension who experienced the unexpected, serious (medically significant) adverse event of special interest Atrial fibrillation a few hours after receiving a dose of mRNA1273 bivalent BA .4/5 as fifth dose in the COVID-19 vaccine series. The patient experienced sudden onset atrial fibrillation post vaccination notified to him by a device. He was advised by his cardiologist to visit the emergency department for evaluation. The patient was started on eliquis and was eventually discharged. The patient had another episode of atrial fibrillation approximately a month after the initial incident and was scheduled for ancillary procedures the next month.  Further details on the clinical course and additional treatment were not provided. The patient's advanced age and concurrent hypertension may be considered as risk factors for atrial fibrillation. The benefit-risk relationship of mRNA-1273 is not affected by this report. Event seriousness assessed as per medical judgment. US-MODERNATX, INC.-MOD-2022-673920:Same reporter US-MODERNATX, INC.-MOD-2022-673920:Same reporter