Atrial fibrillation; Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN); Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN); Diarrhea; Vaccination site pain; Nausea; This spontaneous case was reported by a consumer and describes the occurrence of ATRIAL FIBRILLATION (Atrial fibrillation) in an elderly male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.    Co-suspect products included non-company products IBRUTINIB (IMBRUVICA) for Chronic lymphoid leukemia, TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) for COVID-19 vaccination and VARICELLA ZOSTER VACCINE RGE (CHO) (SHINGRIX) for Prophylaxis.    No Medical History information was reported.   On an unknown date, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form, IBRUTINIB (IMBRUVICA) (Oral) at an unspecified dose, dose of TOZINAMERAN (PFIZER BIONTECH COVID-19 VACCINE) (Intramuscular) 1 dosage form and dose of VARICELLA ZOSTER VACCINE RGE (CHO) (SHINGRIX) (unknown route) 1 dosage form. On an unknown date, the patient experienced ATRIAL FIBRILLATION (Atrial fibrillation) (seriousness criterion medically significant), INTERCHANGE OF VACCINE PRODUCTS (Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN)), COVID-19 IMMUNISATION (Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN)), DIARRHOEA (Diarrhea), VACCINATION SITE PAIN (Vaccination site pain) and NAUSEA (Nausea). At the time of the report, ATRIAL FIBRILLATION (Atrial fibrillation), INTERCHANGE OF VACCINE PRODUCTS (Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN)), COVID-19 IMMUNISATION (Patient received doses of moderna and PFIZER BIONTECH COVID-19 VACCINE (TOZINAMERAN)), DIARRHOEA (Diarrhea) and NAUSEA (Nausea) outcome was unknown and VACCINATION SITE PAIN (Vaccination site pain) had resolved.            Concomitant Drugs were not reported.  Primary reporter did not have the lot number information, because the packaging was discarded.  It was unknown if patient was enrolled in a COVID-19 Vaccine Trial.  Reporter causality of Imbruvica with respect to events: Vaccination site pain, Atrial Fibrillation, Diarrhea and Nausea was not reported.  Reporter causality of Pfizer Biontech Covid-19 vaccine and Shingris with respect to events: Vaccination site pain, Atrial Fibrillation, Diarrhea and Nausea was reported as possible.  No treatment medication was reported by reporter.  Company comment: This spontaneous case concerns a 64 year old male with concomitant use of ibrutinib (Imbruvica) indicated for chronic lymphoid leukemia who experienced the unexpected serious adverse event of special interest atrial fibrillation which occurred at an unknown interval after receiving the third dose of mRNA1273.  Additional non-serious events of diarrhea, nausea and vaccination site pain were also reported in the case. It should be noted that the patient received a dose of different COVID-19 Vaccine (Pfizer Biontech) at an unspecified date prior to the latest dose of mRNA1273 (interchange of vaccine products). Further details regarding the clinical course,  diagnostic test done and treatment were not provided. The patient's elderly age may be considered as a risk factor atrial fibrillation. His concomitant use of ibrutinib may be contributory to the events atrial fibrillation, diarrhea and nausea. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 64 year old male with concomitant use of ibrutinib (Imbruvica) indicated for chronic lymphoid leukemia who experienced the unexpected serious adverse event of special interest atrial fibrillation which occurred at an unknown interval after receiving the third dose of mRNA1273.  Additional non-serious events of diarrhea, nausea and vaccination site pain were also reported in the case. It should be noted that the patient received a dose of different COVID-19 Vaccine (Pfizer Biontech) at an unspecified date prior to the latest dose of mRNA1273 (interchange of vaccine products). Further details regarding the clinical course,  diagnostic test done and treatment were not provided. The patient's elderly age may be considered as a risk factor atrial fibrillation. His concomitant use of ibrutinib may be contributory to the events atrial fibrillation, diarrhea and nausea. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.