Cardiac arrest; This spontaneous case was reported by a consumer and describes the occurrence of CARDIAC ARREST (Cardiac arrest) in a female patient of an unknown age who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis.     Concurrent medical conditions included Diabetic since 2012, Glaucoma and Diabetic retinopathy.   On an unknown date, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, received dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) dosage was changed to at an unspecified dose. On an unknown date, the patient experienced CARDIAC ARREST (Cardiac arrest) (seriousness criteria death and medically significant). The patient died on 05-Apr-2021. The reported cause of death was Cardiac arrest and probable atherosclerotic cardiovascular disease. An autopsy was not performed.            No concomitant medication was reported.  No treatment information was provided.  This case was identified as part of a retrospective clean-up activity where certain emails received in the Moderna mailbox were missed to be booked-in.  The reporter stated the patient was an uncontrolled diabetic and didn´t take care of herself.   Company comment.  This fatal spontaneous case concerns a female of unknown age, with current condition of diabetes mellitus (with uncontrolled diabetes), who received the second dose of her COVID  19 immunization schedule with mRNA-1273 vaccine (unknown schedule) and experienced the serious unexpected event of cardiac arrest. Vaccination date was not reported; hence latency and temporal association cannot be properly assessed; however, it would be within hours from the vaccine: "she went into cardiac arrest and died several hours later". The reported cause of death was probable atherosclerotic cardiovascular disease. No further information regarding the event have been provided for medical review. An autopsy was not performed. Patient's medical history of diabetes with previous uncontrolled diabetes remains a confounder for the reported adverse event. The benefit risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This fatal spontaneous case concerns a female of unknown age, with current condition of diabetes mellitus (with uncontrolled diabetes), who received the second dose of her COVID  19 immunization schedule with mRNA-1273 vaccine (unknown schedule) and experienced the serious unexpected event of cardiac arrest. Vaccination date was not reported; hence latency and temporal association cannot be properly assessed; however, it would be within hours from the vaccine: "she went into cardiac arrest and died several hours later". The reported cause of death was probable atherosclerotic cardiovascular disease. No further information regarding the event have been provided for medical review. An autopsy was not performed. Patient's medical history of diabetes with previous uncontrolled diabetes remains a confounder for the reported adverse event. The benefit risk relationship of mRNA-1273 is not affected by this report.; Reported Cause(s) of Death: Cardiac arrest; probable atherosclerotic cardiovascular disease