Short of breath; Blood clots; Rapid Heartbeat; This spontaneous case was reported by a patient family member or friend and describes the occurrence of DYSPNOEA (Short of breath), THROMBOSIS (Blood clots) and HEART RATE INCREASED (Rapid Heartbeat) in a 52-year-old male patient who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) for COVID-19 prophylaxis.     The patient's past medical history included COVID-19. Previously administered products included for Product used for unknown indication: Flu shot. Past adverse reactions to the above products included No adverse event with Flu shot. Concurrent medical conditions included Blood pressure high (Blood Pressure Medication).    On 14-Dec-2022, the patient received dose of mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (unknown route) 1 dosage form. In January 2023, the patient experienced DYSPNOEA (Short of breath) (seriousness criterion death), THROMBOSIS (Blood clots) (seriousness criteria death and medically significant) and HEART RATE INCREASED (Rapid Heartbeat) (seriousness criterion death). The patient died in January 2023. The reported cause of death was blood clots to his lungs and brain and blood clots to his lungs and brain. It is unknown if an autopsy was performed.        For mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (Unknown), the reporter did not provide any causality assessments.   The patient received Concomitant medications of Antihypertensives. It was reported that the patient was extremely healthy. The patient received other vaccines in the 4 weeks prior to COVID-19 vaccine. The patient went for physical exam on 14-Dec-2022 and his Medical Provider encouraged him to receive a Moderna Bivalent booster Covid-19 dose. The blood clots went to the patient's heart and brain and he died on 28-Jan-2023 or 29-Jan-2023 from blood clots to his lungs and brain. The patient received the Moderna Covid-19 vaccine for his Primary Series and booster shots. The patient received his flu shot around the same time as his Moderna Covid-19 booster shot. Treatment information was not provided.  Company Comment:  This fatal spontaneous case concerns a 52-year-old male patient with medical history  of Covid-19, concurrent medical conditions included Blood pressure high taking medication and flu shot who experienced the unexpected seriousness criteria death and medically significant AESI of thrombosis; the unexpected seriousness criteria death events of dyspnoea and heart rate increased 45 days after a dose of mRNA-1273 bivalent vaccine. The primary schedule of Covid-19 vaccination was with moderna vaccine and the patient felt sick after 1st. dose. Death occurred on January 29, 2023. The cause of death was blood clots to his lungs and brain. It is unknown if an autopsy was performed  The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report. Events seriousness was assessed based on medical judgement.   This case was linked to MOD-2023-710755 (Patient Link).; Reported Cause(s) of Death: blood clots to his lungs and brain; blood clots to his lungs and brain