severe incident of tachycardia that was difficult for the ambulance to control and nearly killed her.; she came home feeling depressed.; total exhaustion and tiredness/She was very tired; headache; This spontaneous case was reported by a patient family member or friend and describes the occurrence of TACHYCARDIA (severe incident of tachycardia that was difficult for the ambulance to control and nearly killed her.) in a 52-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.    Co-suspect product included non-company product ASPIRIN [ACETYLSALICYLIC ACID] chewable tablet for Headache.    No Medical History information was reported.   In 2022, the patient received dose of mRNA-1273 (Spikevax) (Intramuscular) dosage was changed to 1 dosage form. On an unknown date, the patient received dose of mRNA-1273 (Spikevax) (Intramuscular) 1 dosage form and ASPIRIN [ACETYLSALICYLIC ACID] (unknown route) Rapid 500. On an unknown date, the patient experienced TACHYCARDIA (severe incident of tachycardia that was difficult for the ambulance to control and nearly killed her.) (seriousness criterion life threatening), DEPRESSED MOOD (she came home feeling depressed.), FATIGUE (total exhaustion and tiredness/She was very tired) and HEADACHE (headache). At the time of the report, TACHYCARDIA (severe incident of tachycardia that was difficult for the ambulance to control and nearly killed her.) had resolved and DEPRESSED MOOD (she came home feeling depressed.), FATIGUE (total exhaustion and tiredness/She was very tired) and HEADACHE (headache) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Heart rate: 246.     For mRNA-1273 (Spikevax) (Intramuscular), the reporter did not provide any causality assessments.   Concomitant products were not provided. Treatment medication were not reported.  Patient had a severe incident of Tachycardia that was difficult for the emergency doctor  to control and nearly killed her. She is nowstable. Ahead was a normal day at work, where she came home dejected. She was very tired, which is not normal for her. She had a headache and therefore took an aspirin rapid 500 chewable tablet which later turned out to be counterproductive in the situation. She was vaccinated twice against Corona with Moderna, the last time in early 2022.  Company comment: This regulatory case concerns a 52-year-old female patient with no medical history reported, who experienced the unexpected, serious (life-threatening) event of tachycardia an unknown time after a dose of mRNA-1273. The patient had been feeling fatigued and with a headache for which she chewed an aspirin 500. After that, the patient experienced tachycardia of 246 bpm, and was transported by an ambulance to the emergency department. Information regarding clinical evaluation, diagnostic tests and treatment provided has not been disclosed. Outcome was reported as resolved. The benefit-risk relationship of mRNA-1273 is not affected by this report.; Sender's Comments: This regulatory case concerns a 52-year-old female patient with no medical history reported, who experienced the unexpected, serious (life-threatening) event of tachycardia an unknown time after a dose of mRNA-1273. The patient had been feeling fatigued and with a headache for which she chewed an aspirin 500. After that, the patient experienced tachycardia of 246 bpm, and was transported by an ambulance to the emergency department. Information regarding clinical evaluation, diagnostic tests and treatment provided has not been disclosed. Outcome was reported as resolved. The benefit-risk relationship of mRNA-1273 is not affected by this report.