PVC's (premature ventricular contractions)/ gives you a bad feeling/ feel like going to pass out/ makes you feel dizzy; Arrhythmias/feels like you heart is stopping; Full dose given for booster dose; This spontaneous case was reported by a consumer and describes the occurrence of VENTRICULAR EXTRASYSTOLES (PVC's (premature ventricular contractions)/ gives you a bad feeling/ feel like going to pass out/ makes you feel dizzy) and ARRHYTHMIA (Arrhythmias/feels like you heart is stopping) in a 73-year-old female patient who received mRNA-1273 (Moderna COVID-19 Vaccine) (batch nos. 01421A, 038A21A and 028L20A) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.     Patient never had COVID + test or diagnosis.  Previously administered products included for Product used for unknown indication: Shingles vaccine on 04-Apr-2021; for Drug use for unknown indication: Klonopin. Past adverse reactions to the above products included No adverse event with Shingles vaccine; and Withdrawal reaction with Klonopin. Concurrent medical conditions included Allergy to antibiotic (fluoroquinolones, various antibiotics, sulfa), Pre-diabetic and Premature ventricular contractions (A long time ago started,One episode lasted two weeks and resolved; Has a history of PVC's).   On 08-Feb-2021, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) 1 dosage form. On 09-Mar-2021, received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 05-Oct-2021, received third dose of mRNA-1273 (Moderna COVID-19 Vaccine) (Intramuscular) dosage was changed to 1 dosage form. On 05-Oct-2021, the patient experienced VENTRICULAR EXTRASYSTOLES (PVC's (premature ventricular contractions)/ gives you a bad feeling/ feel like going to pass out/ makes you feel dizzy) (seriousness criterion medically significant), ARRHYTHMIA (Arrhythmias/feels like you heart is stopping) (seriousness criterion medically significant) and ACCIDENTAL OVERDOSE (Full dose given for booster dose). The patient was treated with METOPROLOL for Adverse event, at an unspecified dose and frequency and PROPRANOLOL for Adverse event, at an unspecified dose and frequency. At the time of the report, VENTRICULAR EXTRASYSTOLES (PVC's (premature ventricular contractions)/ gives you a bad feeling/ feel like going to pass out/ makes you feel dizzy) and ARRHYTHMIA (Arrhythmias/feels like you heart is stopping) had not resolved and ACCIDENTAL OVERDOSE (Full dose given for booster dose) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Blood pressure measurement: remains low (Low) remains low. On an unknown date, Heart rate: remains low (Low) remains low.         No concomitant medications were reported.  CC: This spontaneous case concerns an 73-year-old female patient, with a relevant history of premature ventricular contractions, who experienced the unexpected, serious (medically significant) Adverse Events of Special Interest of ARRHYTHMIA, and VENTRICULAR EXTRASYSTOLES, that occurred on the same day after the third dose of mRNA-1273 vaccine administration. Additionally, Accidental overdose was also reported. Patient reported that right after getting the 1st booster dose she started experiencing PVC's (premature ventricular contractions) and arrhythmias. Patient felt abnormal and experienced dizziness. Patient consulted with a cardiologist, underwent diagnostics and was prescribed propranolol and metoprolol. Underlying history of premature ventricular contractions, and the patient's age could be the risk factor. Outcome of the event was reported as not resolved. Previously patient had received the primary series of mRNA-1273 vaccine as dose 1 and 2 with sore arm as the event reported. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns an 73-year-old female patient, with a relevant history of premature ventricular contractions, who experienced the unexpected, serious (medically significant) Adverse Events of Special Interest of ARRHYTHMIA, and VENTRICULAR EXTRASYSTOLES, that occurred on the same day after the third dose of mRNA-1273 vaccine administration. Additionally, Accidental overdose was also reported. Patient reported that right after getting the 1st booster dose she started experiencing PVC's (premature ventricular contractions) and arrhythmias. Patient felt abnormal and experienced dizziness. Patient consulted with a cardiologist, underwent diagnostics and was prescribed propranolol and metoprolol. Underlying history of premature ventricular contractions, and the patient's age could be the risk factor. Outcome of the event was reported as not resolved. Previously patient had received the primary series of mRNA-1273 vaccine as dose 1 and 2 with sore arm as the event reported. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.