Post operative atrial fibrillation; Diverticulitis has been worsening; blood pressure very low; Red spot at the injection site; fine rash from waist up, started on right arm, a lot of different spots in body including chin, left thumb, hairline on the right side, knee, belly, and 5 spots around waist, 105 spots of rashes appeared on legs.; This spontaneous case was reported by a consumer and describes the occurrence of ATRIAL FIBRILLATION (Post operative atrial fibrillation) and DIVERTICULITIS (Diverticulitis has been worsening) in a 72-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch no. 002F21A) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     The patient's past medical history included Diverticulitis (Diverticulitis which had been worsening for the last 5 years.) and Surgery (diverticulitis surgery which was successfully done). Concomitant products included CALCIUM for an unknown indication.    On 27-Aug-2021, the patient received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) .5 milliliter. On an unknown date, the patient experienced ATRIAL FIBRILLATION (Post operative atrial fibrillation) (seriousness criterion medically significant), DIVERTICULITIS (Diverticulitis has been worsening) (seriousness criterion medically significant), HYPOTENSION (blood pressure very low), VACCINATION SITE ERYTHEMA (Red spot at the injection site) and RASH (fine rash from waist up, started on right arm, a lot of different spots in body including chin, left thumb, hairline on the right side, knee, belly, and 5 spots around waist, 105 spots of rashes appeared on legs.). The patient was treated with METOPROLOL for Atrial fibrillation, at an unspecified dose and frequency; PARACETAMOL (TYLENOL) at an unspecified dose and frequency and Surgery (Diverticulitis surgery) for Diverticulitis. At the time of the report, ATRIAL FIBRILLATION (Post operative atrial fibrillation), DIVERTICULITIS (Diverticulitis has been worsening), HYPOTENSION (blood pressure very low) and VACCINATION SITE ERYTHEMA (Red spot at the injection site) outcome was unknown and RASH (fine rash from waist up, started on right arm, a lot of different spots in body including chin, left thumb, hairline on the right side, knee, belly, and 5 spots around waist, 105 spots of rashes appeared on legs.) had not resolved.       Company comment: This spontaneous case concerns an elderly female patient aged 72 years with relevant medical history of Diverticulitis reported, who experienced the unexpected serious (medically significant) events of Atrial fibrillation (AESI) and Diverticulitis (reported as Diverticulitis has been worsening) on unknown dates after third dose of mRNA-1273 vaccination. Patient had aggravation of Diverticulitis for the past 5 years for which she underwent surgery. She developed post operative atrial fibrillation, treated with blood thinners and metaprolol.  As she developed hypotension metaprolol was stopped. Patient had generalized rash two weeks after surgery for which dermatologist consultation was done and awaiting a patch test result for diagnosis. No further information on risk factors, detailed clinical course and investigations was available in the report. Outcome of the events was not known at the time of report. Patient had received 1st and 2nd dose of mRNA-1273 vaccine at an interval of 28 days. Relevant medical history remains a confounder to the event Diverticulitis(aggravation) and elderly age of the patient remains a risk factor to the event Atrial fibrillation. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed as per medical judgement and available information.     It was unknown if patient had allergies to medications, food and other products. It was unknown if patient had COVID positive test or diagnosis. The patient did not receive other vaccines within 1 month prior to Moderna COVID-19 vaccine. The patient had some wild reactions to the three doses of the Moderna COVID-19 Vaccine. The patient did not get a COVID arm. The patient did not remember how long symptoms lasted for. Additionally, the patient had a history of diverticulitis which had been worsening for the last 5 years. Recently, she had to go for a diverticulitis surgery which was successfully done. However, she ended up with post operative atrial fibrillation. The patient had to stop the Metoprolol as that was making blood pressure very low. Two weeks after the surgery she started getting a fine rash from waist up. It started on right arm and was in a lot of different spots in body including chin, left thumb, hairline on the right side, knee, belly, and 5 spots around waist as well. This all occurred in the first round of rashes. A few days later the rashes seemed to be all gone. However, soon after another 105 spots of rashes appeared on legs. The patient seeing a dermatologist for this and was still waiting on results of patch test for a diagnosis. The patient mentioned that drug reaction was still a possibility for these rashes. The event redness and rash did not caused patient to seek medical care office visit, Urgent care, ER, hospitalized. The patient did not experience similar event in past. The event redness recovered in reasonable amount of time. The outcome of event rash was residual effect.  Treatment also included Blood thinners for atrial fibrillation and Tylenol for side effects related to the vaccine.   This case was linked to MOD-2022-628837, MOD-2022-628835 (Patient Link).; Sender's Comments: This spontaneous case concerns an elderly female patient aged 72 years with relevant medical history of Diverticulitis reported, who experienced the unexpected serious (medically significant) events of Atrial fibrillation (AESI) and Diverticulitis (reported as Diverticulitis has been worsening) on unknown dates after third dose of mRNA-1273 vaccination. Patient had aggravation of Diverticulitis for the past 5 years for which she underwent surgery. She developed post operative atrial fibrillation, treated with blood thinners and metaprolol.  As she developed hypotension metaprolol was stopped. Patient had generalized rash two weeks after surgery for which dermatologist consultation was done and awaiting a patch test result for diagnosis. No further information on risk factors, detailed clinical course and investigations was available in the report. Outcome of the events was not known at the time of report. Patient had received 1st and 2nd dose of mRNA-1273 vaccine at an interval of 28 days. Relevant medical history remains a confounder to the event Diverticulitis(aggravation) and elderly age of the patient remains a risk factor to the event Atrial fibrillation. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report. Event seriousness assessed as per medical judgement and available information.