Recurrence of Thrombotic Thrombocytopenic Purpura; Transient right-sided weakness; Slurred speech; Paresthesia; This literature-study case was reported in a literature article and describes the occurrence of THROMBOTIC THROMBOCYTOPENIC PURPURA (Recurrence of Thrombotic Thrombocytopenic Purpura) and HEMIPARESIS (Transient right-sided weakness) in a 48-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 vaccination. The occurrence of additional non-serious events is detailed below.   The patient's past medical history included Thrombotic thrombocytopenic purpura (Refractory), COVID-19 (COVID-19 2 months before his presentation, which did not require hospitalization.) and Idiopathic thrombocytopenic purpura (diagnosed with ITP 5 years ago, which was treated with steroids and rituximab). Concurrent medical conditions included Type 2 diabetes mellitus. Concomitant products included INSULIN for Type 2 diabetes mellitus.    On an unknown date, the patient received first dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On an unknown date, the patient experienced THROMBOTIC THROMBOCYTOPENIC PURPURA (Recurrence of Thrombotic Thrombocytopenic Purpura) (seriousness criterion medically significant), HEMIPARESIS (Transient right-sided weakness) (seriousness criterion medically significant), DYSARTHRIA (Slurred speech) and PARAESTHESIA (Paresthesia). The patient was treated with RITUXIMAB for Thrombotic thrombocytopenic purpura, at an unspecified dose and frequency. At the time of the report, THROMBOTIC THROMBOCYTOPENIC PURPURA (Recurrence of Thrombotic Thrombocytopenic Purpura), HEMIPARESIS (Transient right-sided weakness), DYSARTHRIA (Slurred speech) and PARAESTHESIA (Paresthesia) had resolved.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): On an unknown date, ADAMTS13 activity assay: <3% (abnormal) The PLASMIC score used to predict ADAMTS13 deficiency in suspected TTP patients was 7 points showing that the patient is at high risk of having severe ADAMTS13 deficiency, thus requiring emergent plasmapheresis. ADAMTS13 activity later resulted as <3%. On an unknown date, ADAMTS13 inhibitor screen assay: 6.6 beu (High) ADAMTS13 inhibitor was 6.6 BEU (normal <0.4).. On an unknown date, Blood bilirubin: 5.0 (abnormal) total bilirubin 5.0 with indirect bilirubin predominance. On an unknown date, Blood fibrinogen: 417?mg/dl (abnormal) fibrinogen 417?mg/dL. On an unknown date, Blood lactate dehydrogenase: 884?u/l (abnormal) lactate dehydrogenase (LDH) 884?U/L. On an unknown date, Cardiopulmonary exercise test: normal (normal) The patient had a normal cardiopulmonary exam, and his neurological exam was intact with complete recovery of transient symptoms. Examination of the skin and mucosa did not show any petechiae, purpura, or active bleeding.. On an unknown date, Haemoglobin: 8.8?g/dl (Low) hemolytic anemia. On an unknown date, Haptoglobin: <10?mg/dl (abnormal) haptoglobin<10?mg/dL. On an unknown date, Platelet count: 130.000/ul (normal) patient was reported to have normal platelet counts (130.000/uL) approximately three months before the presentation. and 10x103/dl (abnormal) platelet count 10?×?103/dL (baseline platelet count of 130?×?103/dL).. On an unknown date, SARS-CoV-2 test: negative (Negative) patient's COVID-19 PCR test was negative..     mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown) was temporarily withheld on an unknown date.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter considered THROMBOTIC THROMBOCYTOPENIC PURPURA (Recurrence of Thrombotic Thrombocytopenic Purpura), HEMIPARESIS (Transient right-sided weakness), DYSARTHRIA (Slurred speech) and PARAESTHESIA (Paresthesia) to be possibly related.    Patient medical records elucidated that he had a diagnosis of TTP for eight years, a total of 4 episodes in the past for which he was treated with plasmapheresis, steroids, and rituximab. Further treatment options were not initiated since the patient was lost to follow-up in between his relapses. He was also diagnosed with ITP 5 years ago, which was treated with steroids and rituximab.  Patient had a full recovery after a 10-day course of plasmapheresis in addition to glucocorticoids and rituximab. The patient was to complete outpatient rituximab therapy and steroid tapering with hematology follow-up on discharge. His platelet and hemoglobin count was normalized on the day of discharge. The second dose of the COVID-19 vaccine was deferred.  Treatment information was also included Steroid.  This case concerns a 48 year-old, male with a history of diabetes mellitus, Thrombotic thrombocytopenic purpura (Refractory), COVID-19 (COVID-19 2 months before his presentation, which did not require hospitalization.) and Idiopathic thrombocytopenic purpura  , who experienced the unexpected events THROMBOTIC THROMBOCYTOPENIC PURPURA (seriousness criterion medically significant), CONDITION AGGRAVATED, HEMIPARESIS, DYSARTHRIA and PARAESTHESIA, all resolved . The event is consistent with the current understanding of the mechanism of action of the study medication. The benefit-risk relationship of mRNA-1273 Moderna vaccine in not affected by this report   Most recent FOLLOW-UP information incorporated above includes: On 17-Sep-2021: Follow up received by safety 17-Sep-2021 included an Email received contains no new information.; Sender's Comments: This case concerns a 48 year-old, male with a history of diabetes mellitus, Thrombotic thrombocytopenic purpura (Refractory), COVID-19 (COVID-19 2 months before his presentation, which did not require hospitalization.) and Idiopathic thrombocytopenic purpura  , who experienced the unexpected events THROMBOTIC THROMBOCYTOPENIC PURPURA (seriousness criterion medically significant), CONDITION AGGRAVATED, HEMIPARESIS, DYSARTHRIA and PARAESTHESIA, all resolved . The event is consistent with the current understanding of the mechanism of action of the study medication. The benefit-risk relationship of mRNA-1273 Moderna vaccine in not affected by this report