Thrombotic thrombocytopenic purpura; Hemolytic anemia with schistocytes were noted on testing; This literature-non-study case was reported in a literature article and describes the occurrence of THROMBOTIC THROMBOCYTOPENIC PURPURA (Thrombotic thrombocytopenic purpura) and HAEMOLYTIC ANAEMIA (Hemolytic anemia with schistocytes were noted on testing) in a 63-year-old female patient who received mRNA-1273 (Spikevax) for COVID-19 prophylaxis.   LITERATURE REFERENCE:     Concurrent medical conditions included Hypertension, Diabetes mellitus, Chronic kidney disease, HIV infection and Thrombotic thrombocytopenic purpura.    On an unknown date, the patient received second dose of mRNA-1273 (Spikevax) (unknown route) 1 dosage form. On an unknown date, the patient experienced THROMBOTIC THROMBOCYTOPENIC PURPURA (Thrombotic thrombocytopenic purpura) (seriousness criterion medically significant) and HAEMOLYTIC ANAEMIA (Hemolytic anemia with schistocytes were noted on testing) (seriousness criterion medically significant). At the time of the report, THROMBOTIC THROMBOCYTOPENIC PURPURA (Thrombotic thrombocytopenic purpura) and HAEMOLYTIC ANAEMIA (Hemolytic anemia with schistocytes were noted on testing) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, ADAMTS13 activity assay: ADAMTS13 activity was less than 5% (<5%)..     For mRNA-1273 (Spikevax) (Unknown), the reporter considered THROMBOTIC THROMBOCYTOPENIC PURPURA (Thrombotic thrombocytopenic purpura) and HAEMOLYTIC ANAEMIA (Hemolytic anemia with schistocytes were noted on testing) to be related.    No concomitant medication was reported.  Patient was presented with several days of shortness of breath on exertion, chest tightness, low-grade fever, and bruising thirty-three days after receiving the second dose of the mRNA-1273 COVID-19 vaccine.   Temporizing treatment with fresh frozen plasma was started immediately on presentation, and treatment was continued with daily therapeutic plasma exchange and corticosteroids.  Stated that TTP was considered in patients who presented with thrombocytopenia after COVID-19 vaccination, especially if there was a past history of TTP.  Author reported that thrombotic thrombocytopenic purpura (TTP) was a rare disease characterized by thrombocytopenia, microangiopathic hemolytic anemia, and ischemic organ damage. Several cases of TTP associated with administration of COVID-19 vaccines.  Company comment: This is a literature case concerning a 63-year-old female patient with relevant medical history of HIV infection and remote history of Thrombotic thrombocytopenic purpura, who experienced the unexpected serious (medically significant) events of haemolytic anemia and AESI of Thrombotic thrombocytopenic purpura. The events occurred unknown days after the second dose of mRNA-1273 vaccine. Patient presented after several days of shortness of breath on excursion, chest tightness, low-grade fever and bruising. Thrombocytopenia and hemolytic anemia with schistocytes were noted on testing and ADAMTS13 activity was <5 %. Treatment with fresh frozen plasma started immediately, continued with daily therapeutic plasma exchange and corticosteroids. No further information disclosed about diagnostic tests performed or treatments received. Underlying medical history remains as a confounder in this case. Age and gender are a risk factors for the event of Thrombotic thrombocytopenic purpura. At the time of the report, the outcome of events was unknown. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.; Sender's Comments: This is a literature case concerning a 63-year-old female patient with relevant medical history of HIV infection and remote history of Thrombotic thrombocytopenic purpura, who experienced the unexpected serious (medically significant) events of haemolytic anemia and AESI of Thrombotic thrombocytopenic purpura. The events occurred unknown days after the second dose of mRNA-1273 vaccine.  Patient presented after several days of shortness of breath on excursion, chest tightness, low-grade fever and bruising. Thrombocytopenia and hemolytic anemia with schistocytes were noted on testing and ADAMTS13 activity was <5 %. Treatment with fresh frozen plasma started immediately, continued with daily therapeutic plasma exchange and corticosteroids. No further information disclosed about diagnostic tests performed or treatments received. Underlying medical history remains as a confounder in this case. Age and gender are a risk factors for the event of Thrombotic thrombocytopenic purpura. At the time of the report, the outcome of events was unknown. The benefit-risk relationship of mRNA-1273 vaccine is not affected by this report.