Sinus bradycardia; Felt like it will occur again 1 week later/the patient does not feel normal; This spontaneous case was reported by a patient and describes the occurrence of SINUS BRADYCARDIA (Sinus bradycardia) in a 58-year-old patient of an unknown gender who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Concurrent medical conditions included Diabetes.    In April 2021, the patient received second dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. In August 2021, the patient experienced SINUS BRADYCARDIA (Sinus bradycardia) (seriousness criterion hospitalization). On an unknown date, the patient experienced FEELING ABNORMAL (Felt like it will occur again 1 week later/the patient does not feel normal). At the time of the report, SINUS BRADYCARDIA (Sinus bradycardia) was resolving and FEELING ABNORMAL (Felt like it will occur again 1 week later/the patient does not feel normal) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In August 2021, Heart rate: down in the 40's. and 70-80's. On an unknown date, Glycosylated haemoglobin: 9.3 initially and 6.6 currently. On an unknown date, Heart rate: normally in the 80's.         No concomitant and treatment medication was reported. It started about 4 month after the second shot (Apr-2021), the patient had shortness of breath, was tired easily and discovered the heart rate to be down in the 40's. Prior to this, the patient's HR was normally in the 80s. The patient was kept overnight for observations and then released. HR returned to 70-80s. It was reported that patient heart was monitored for a month. Echo and Stress test was done. But the cardiologist told that he was not concerned about HR drop. The patient then had 4 more episodes approx. 1 month. apart, kept overnight and then released. The last two episodes occurred 1 week apart and the patient felt like it will occur again.  Company Comment: This spontaneous case concerns a 58-year-old patient (gender not specified) with no relevant medical history reported, who experienced the unexpected serious (hospitalization) AESI of Sinus bradycardia which occurred approximately 4 months after the second dose of mRNA-1273 vaccine. Patient had shortness of breath, tiredness and discovered the heart rate to be down in the 40's. Prior to this, the patient's heart rate was normally in the 80s. The patient was kept overnight for observations and then released. Heart rate returned to 70-80s. The patient then had 4 more episodes approx. 1 month apart, kept overnight and then discharged. The last two episodes occurred 1 week apart and the patient sort of felt like it will occur again 1 week later. Patient heart was monitored for a month. Echo and Stress test was done, no significant changes were reported. No further details on clinical course, other lab test results and treatment received were reported. The outcome of the event was reported as resolving. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.; Sender's Comments: This spontaneous case concerns a 58-year-old patient (gender not specified) with no relevant medical history reported, who experienced the unexpected serious (hospitalization) AESI of Sinus bradycardia which occurred approximately 4 months after the second dose of mRNA-1273 vaccine. Patient had shortness of breath, tiredness and discovered the heart rate to be down in the 40's. Prior to this, the patient's heart rate was normally in the 80s. The patient was kept overnight for observations and then released. Heart rate returned to 70-80s. The patient then had 4 more episodes approx. 1 month apart, kept overnight and then discharged. The last two episodes occurred 1 week apart and the patient sort of felt like it will occur again 1 week later. Patient heart was monitored for a month. Echo and Stress test was done, no significant changes were reported. No further details on clinical course, other lab test results and treatment received were reported. The outcome of the event was reported as resolving. The benefit-risk relationship of mRNA-1273 Vaccine is not affected by this report.