was not administered the 2nd dose of the vaccine; atrial fibrillation; afib attack/atrial fibrillation; itchy ant bite like lesions which popped on different sites of her body; itchy ant bite like lesions which popped on different sites of her body; This spontaneous case was reported by a consumer (subsequently medically confirmed) and describes the occurrence of ATRIAL FIBRILLATION (afib attack/atrial fibrillation) and ATRIAL FIBRILLATION (atrial fibrillation) in a 70-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     No medical history was provided by the reporter.  The patient's past medical history included Atrial fibrillation and Cardiac ablation on 06-Jul-2020. Concomitant products included RIVAROXABAN (XARELTO) for an unknown indication.    On 03-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 04-Mar-2021, the patient experienced ATRIAL FIBRILLATION (afib attack/atrial fibrillation) (seriousness criterion medically significant). In March 2021, the patient experienced PRURITUS (itchy ant bite like lesions which popped on different sites of her body) and SKIN LESION (itchy ant bite like lesions which popped on different sites of her body). On 04-Apr-2021, the patient experienced ATRIAL FIBRILLATION (atrial fibrillation) (seriousness criterion medically significant). On 12-Jul-2021, the patient experienced PRODUCT DOSE OMISSION ISSUE (was not administered the 2nd dose of the vaccine). The patient was treated with FLECAINIDE for Adverse event, at a dose of 100 mg twice a day and HYDROCORTISONE (CORTISONE [HYDROCORTISONE]) for Adverse event, at an unspecified dose and frequency. In April 2021, ATRIAL FIBRILLATION (afib attack/atrial fibrillation) had resolved. At the time of the report, ATRIAL FIBRILLATION (atrial fibrillation), PRURITUS (itchy ant bite like lesions which popped on different sites of her body) and SKIN LESION (itchy ant bite like lesions which popped on different sites of her body) outcome was unknown and PRODUCT DOSE OMISSION ISSUE (was not administered the 2nd dose of the vaccine) had resolved.        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.   On 04-Mar-2021, in the morning, the patient experienced had an atrial fibrillation attack and went to the emergency room (ER) where she was given medications to control it. On 04-Apr-2021, the patient had another atrial fibrillation attack and again she went to the ER. The patient had two more atrial fibrillation attacks on unspecified dates in April and she managed these at home by doubling up on her medication. Patient reports that with this, it took 6-7 hours before the atrial fibrillation got controlled. Treatment included: She had an ablation last 06Jul2021 for the atrial fibrillation.  Company comment: Based on the current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded. Noting the history of atrial fibrillation may remain as risk factor. This report refers to a case of lack of product dose omission for mRNA-1273, lot # unknown.; Sender's Comments: Based on the current available information and temporal association between the use of the product and the start date of the event, a causal relationship cannot be excluded. Noting the history of atrial fibrillation may remain as risk factor. This report refers to a case of lack of product dose omission for mRNA-1273, lot # unknown.