two cases of vaccine induced TTP; This is a literature report.  A 19-year-old female patient received BNT162b2 (BNT162B2), as dose 1, single (Batch/Lot number: unknown) for covid-19 immunisation. The patient's relevant medical history included: "acquired TTP" (unspecified if ongoing), notes: at age 14 years; "systemic lupus erythematosus (SLE)-specific autoantibodies" (unspecified if ongoing), notes: specific autoantibodies without evidence of organ dysfunction; "TTP relapse" (unspecified if ongoing), notes: at age 18. The patient took concomitant medications. The following information was reported: THROMBOTIC THROMBOCYTOPENIC PURPURA (hospitalization, medically significant), 2 days after the suspect product(s) administration, outcome "unknown", described as "two cases of vaccine induced TTP". The patient underwent the following laboratory tests and procedures: ADAMTS13 activity assay: less than 5, notes: confirming a relapse of TTP; Autoantibody test: specific autoantibodies, notes: without evidence of organ dysfunction; Blood bilirubin unconjugated: 5.3 mg/dl; Blood lactate dehydrogenase: 836, notes: Units: U/L; Complement factor C3: 129 mg/dl; Complement factor C4: 30 mg/dl; Haemoglobin: 12.4 g/dl; Admission labs: were significant for thrombocytopenia, notes: and signs of intravascular hemolysis; physical examination: bilateral suborbital and lower extremity petechiae, notes: and bruising at IV insertion sites; Platelet count: 7000 cells/uL; Red blood cell schistocytes: yes; Reticulocyte count: 0.103 x10 6/mm3; SARS-CoV-2 test: not detected at time of relapse. Therapeutic measures were taken as a result of thrombotic thrombocytopenic purpura. Clinical course: Patient experienced fever, ecchymoses, and hemoglobinuria 2 days after receiving the initial dose of the Pfizer-BioNTech COVID-19 vaccine. Her physical examination was notable for bilateral suborbital and lower extremity petechiae and bruising at IV insertion sites. Of note, her prior disease course had been complicated by the development of systemic lupus erythematosus (SLE)-specific autoantibodies without evidence of organ dysfunction, and a prior TTP relapse at age 18. Treatment included daily therapeutic plasma exchange (TPE) for 4 days, methylprednisolone 1 g daily for 3 days followed by a taper, rituximab 375 mg/m2 weekly for four doses, and caplacizumab 11 mg daily for 28 days. Treatment side effects were none to date. Current status of TTP was reported as "In remission".  No follow-up attempts are possible; information about lot/batch number cannot be obtained. No further information is expected.; Sender's Comments: Based on the available information and the close drug event temporal association, a possible contributory role of suspect product BNT162B2 to the development of events thrombotic thrombocytopenic purpura cannot be totally excluded. The impact of this report on the benefit/risk profile of the Pfizer product is evaluated as part of Pfizer procedures for safety evaluation, including the review and analysis of aggregate data for adverse events. Any safety concern identified as part of this review, as well as any appropriate action in response, will be promptly notified to RAs, Ethics Committees, and Investigators, as appropriate.,Linked Report(s) : US-PFIZER_INC-202200544326 Same article/drug/event and different patient.;US-PFIZER INC-202200555943 Same article and different drug, event, patient