Afib wt RVR; Tachycardia; General malaise; Refused 2nd covid vax; Fatigue; After the shot I got real real dizzy; I didn't feel sick, but I didn't feel right; I slept most of the day; I didn't have appetite; This spontaneous case was reported by a consumer and describes the occurrence of ATRIAL FIBRILLATION (Afib wt RVR) and TACHYCARDIA (Tachycardia) in an 85-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 11MZ0A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Arthritis in 2010. Concurrent medical conditions included Drug allergy (aspirin), Drug allergy (Avelox), Drug allergy (morphine), Hypertension since 12-Dec-2011 and Hypothyroidism since 24-Sep-2014. Concomitant products included LEVOTHYROXINE SODIUM (SYNTHROID) from 24-Sep-2014 to an unknown date, NEBIVOLOL HYDROCHLORIDE (BYSTOLIC) from 12-Dec-2011 to an unknown date and LOSARTAN from 17-Mar-2021 to an unknown date for an unknown indication.    On 15-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 15-Mar-2021, the patient experienced ATRIAL FIBRILLATION (Afib wt RVR) (seriousness criteria hospitalization and medically significant), TACHYCARDIA (Tachycardia) (seriousness criterion hospitalization), DIZZINESS (After the shot I got real real dizzy), FEELING ABNORMAL (I didn't feel sick, but I didn't feel right), SOMNOLENCE (I slept most of the day) and DECREASED APPETITE (I didn't have appetite). On an unknown date, the patient experienced MALAISE (General malaise), INTENTIONAL PRODUCT USE ISSUE (Refused 2nd covid vax) and FATIGUE (Fatigue). The patient was hospitalized from 15-Mar-2021 to 18-Mar-2021 due to ATRIAL FIBRILLATION and TACHYCARDIA. The patient was treated with CARVEDILOL at a dose of 6.25 mg. On 20-Mar-2021, DIZZINESS (After the shot I got real real dizzy), FEELING ABNORMAL (I didn't feel sick, but I didn't feel right), SOMNOLENCE (I slept most of the day) and DECREASED APPETITE (I didn't have appetite) had resolved. On 01-Jun-2021, ATRIAL FIBRILLATION (Afib wt RVR) had resolved. At the time of the report, TACHYCARDIA (Tachycardia), MALAISE (General malaise), INTENTIONAL PRODUCT USE ISSUE (Refused 2nd covid vax) and FATIGUE (Fatigue) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 15-Mar-2021, Blood pressure measurement: high (High) high. On 15-Mar-2021, Heart rate: high (High) 150. On 20-Mar-2021, Blood pressure measurement: 139/79 (normal) 139/79. On 20-Mar-2021, Heart rate: low (Low) 53.     The action taken with mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) was unknown.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular), the reporter did not provide any causality assessments.   No treatment medications were not provided.  Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded   Most recent FOLLOW-UP information incorporated above includes: On 02-Jul-2021: Follow-up information received included: Added medical history, concomitant medications and added new event of Atrial Fib with RVR.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the events, a causal relationship cannot be excluded