blood clots; developed blood clots which went to his spleen and killed half of it; feels hot all the time; headaches; This spontaneous case was reported by a patient and describes the occurrence of THROMBOSIS (blood clots) and SPLENIC INJURY (developed blood clots which went to his spleen and killed half of it) in a male patient of an unknown age who received mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (batch no. ASKU) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.     Previously administered products included for COVID-19 prophylaxis: Moderna COVID-19 Vaccine (Dose 1) and Moderna COVID-19 Vaccine (Dose 2). Past adverse reactions to the above products included No adverse event with Moderna COVID-19 Vaccine and Moderna COVID-19 Vaccine.    On an unknown date, 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. On an unknown date, the patient experienced THROMBOSIS (blood clots) (seriousness criterion medically significant), SPLENIC INJURY (developed blood clots which went to his spleen and killed half of it) (seriousness criterion medically significant), FEELING HOT (feels hot all the time) and HEADACHE (headaches). At the time of the report, THROMBOSIS (blood clots), FEELING HOT (feels hot all the time) and HEADACHE (headaches) had not resolved and SPLENIC INJURY (developed blood clots which went to his spleen and killed half of it) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, Electrocardiogram ambulatory: not able to see afib on both occasions.     For mRNA-1273 BIVALENT .222 (MODERNA COVID-19 VACCINE, BIVALENT (ORIGINAL AND OMICRON BA.4/BA.5)) (Unknown), the reporter considered SPLENIC INJURY (developed blood clots which went to his spleen and killed half of it) to be not related. No further causality assessments were provided for THROMBOSIS (blood clots), FEELING HOT (feels hot all the time) and HEADACHE (headaches).    Concomitant medication was not provided.  It was reported that patient had the 2 shots of the vaccine one and a half years ago the a few months later had the booster dose. He did not have his vaccination card with him at the time of the call so he was not able to provide the vaccination details. After an unspecified period of time, he developed blood clots which went to his spleen and killed half of it. His doctor said that this could not be due to the vaccine. He had headaches towards the end of the day and felt hot all the time. He was also hooked to heart monitor twice to see where the clot is coming from but they were not able to see afib on both occasions. He had blood thinners for a long time.  Company Comment: This is a Spontaneous case reported by a patient, concerning a male patient of unknown age, with no medical history reported, who experienced the unexpected and serious (due to medically significant) events of Thrombosis (AESI) and Splenic injury, which occurred on an unknown date after a booster dose of mRNA-1273.222 vaccine. Patient reported that after an unspecified period of time after vaccination, he developed blood clots, which went to his spleen and "killed half of it". His doctor said that this could not be due to the vaccine. Heart monitor was performed twice, with no finding of atrial fibrillation. Patient has received blood thinners for a long time. At the time of the report, Thrombosis had not resolved, and Splenic injury outcome was unknown. The benefit-risk relationship of mRNA- 1273.222 vaccine is not affected by this report.     This case was linked to US-MODERNATX, INC.-MOD-2023-697477, US-MODERNATX, INC.-MOD-2023-697513, US-MODERNATX, INC.-MOD-2023-697562 (Linked Report).; Sender's Comments:  US-MODERNATX, INC.-MOD-2023-697477:brother case US-MODERNATX, INC.-MOD-2023-697513:Son's case US-MODERNATX, INC.-MOD-2023-697562:older brother case