Tested positive for COVID; Heart palpitation; Heart arrhythmia; This spontaneous case was reported by a patient and describes the occurrence of ARRHYTHMIA (Heart arrhythmia) and COVID-19 (Tested positive for COVID) in a 50-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 042B21A. and 008B21A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Previously administered products included for Product used for unknown indication: ciprofloxacin, ciprofloxacin, ciprofloxacin and ciprofloxacin. Past adverse reactions to the above products included Fatigue with ciprofloxacin; Flu like symptoms with ciprofloxacin; Myalgia with ciprofloxacin; and Nausea with ciprofloxacin. Concurrent medical conditions included Allergy to antibiotic (ciprofloxacin).   On 19-Mar-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 16-Apr-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 14-Dec-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. In January 2022, the patient experienced ARRHYTHMIA (Heart arrhythmia) (seriousness criterion medically significant) and PALPITATIONS (Heart palpitation). On 30-May-2022,  after starting mRNA-1273 (Moderna COVID-19 Vaccine), the patient experienced COVID-19 (Tested positive for COVID) (seriousness criterion medically significant). At the time of the report, ARRHYTHMIA (Heart arrhythmia) and PALPITATIONS (Heart palpitation) outcome was unknown and COVID-19 (Tested positive for COVID) had not resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On 30-May-2022, SARS-CoV-2 test: positive (Positive) positive.         No concomitant medication was provided by patient. Patient received the primary series at a doctor office. Patient received the booster dose at a pharmacy. Patient stated she had no side effects after the primary series. She noticed side effects after booster. She started having heart palpitation and heart arrythmia in January 2022. Patient currently had COVID. She took an at home test yesterday and tested positive. Her symptoms started yesterday, and they were fever, chills, headache, fatigue, body muscular aches, dry cough, nasal, and sinus congestion.  Patient had never been diagnosed with myocarditis or pericarditis. Patient was taking medications. Patient's HCP was aware of side effects.  Patient stated her HCP referred her to a Cardiologist. She was currently wearing a patch monitor.  She had seen the cardiologist once and she was supposed to go back in a few weeks. Patient was allergic ciprofloxacin antibiotic, and her symptoms are Flu like symptoms body ache, nausea, and fatigue. Patient stated she was going back to sleep and wanted to end the call.  Company comment: This spontaneous case concerns a 50-year-old female patient, with no relevant medical history reported, who experienced the serious (medically significant) unexpected AESI events of Arrhythmia and COVID-19 after booster dose of mRNA-1273 vaccine. Patient reported to have arrhythmia and palpitations on an unknown date in January 2022 with outcome unknown. She was tested positive for COVID-19 on 30th May 2022(5 months 17 days after booster dose), along with symptoms of fever, headache, chills, fatigue, myalgia and congestion and is on treatment. She was referred to cardiologist by her HCP and is wearing a patch monitor and has been advised further follow ups. Outcome of the event COVID-19 is not resolved at the time of report. She had received 1st and 2nd dose of Moderna vaccine at an interval of 28 days and approximately 7 months 28 days prior to booster dose.  The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 50-year-old female patient, with no relevant medical history reported, who experienced the serious (medically significant) unexpected AESI events of Arrhythmia and COVID-19 after booster dose of mRNA-1273 vaccine. Patient reported to have arrhythmia and palpitations on an unknown date in January 2022 with outcome unknown. She was tested positive for covid -19 on 30th May 2022(5 months 17 days after booster dose), along with symptoms of fever, headache, chills, fatigue, myalgia and congestion and is on treatment. She was referred to cardiologist by her HCP and is wearing a patch monitor and has been advised further follow ups. Outcome of the event covid -19 is not resolved at the time of report. She had received 1st and 2nd dose of Moderna vaccine at an interval of 28 days and approximately 7 months 28 days prior to booster dose.  The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.