IMMUNE THROMBOCYTOPENIA; This spontaneous report. This report concerned a 52 year old male of an unspecified race and ethnicity. The objective of the authors was to highlight that Immune thrombocytopenia (ITP) has been associated with immunizations with various proposed mechanisms, including overactivation of the immune system and production of antibodies against circulating platelets. ITP has also been associated with several viral infections, including HCV, HIV, and most recently, active SARS-CoV-2 infection. In this article they presented a case of a 52-year-old male with no past medical history who sought evaluation with his primary care physician for upper and lower extremity ecchymosis of one week duration. The patient's height, and weight were not reported. The patient's pre-existing medical conditions included: The patient had no past medical history. The patient denied any recent flu-like symptoms, gingival bleeding, epistaxis, headaches, visual changes, abdominal pain, shortness of breath, leg pain, or swelling. He also denied any family history of bleeding or autoimmune disorders or other symptoms, systemic lupus erythematosus was effectively ruled out. The patient was not infectious, ruling out sepsis and viral causes, such as SARS-CoV-2, HIV, and HCV were negative. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: unknown, expiry date: unknown) dose, start therapy date were not reported, 1 total administered for covid-19 prophylaxis. The batch number was not reported. Per procedure, no follow-up will be requested for this case. Concomitant medications were reported as occasional nonsteroidal anti-inflammatory drugs for chronic back pain.  On an unspecified date, 16 days after vaccination, the patient experienced immune thrombocytopenia, and was hospitalized in emergency department(date unspecified). Initial workup in the emergency department revealed Laboratory data (dates unspecified) included: ANA unremarkable, Acid base balance unremarkable, Activated partial thromboplastin time (NR: 25 - 38) 29.9 sec, Bilirubin (NR: 5.13 - 20.5) 5.13 umol/L, Bilirubin direct (NR: 0.0 - 6.8) 1.7 umol/L, Blood test HCV was unremarkable, Fibrin D dimer (NR: 0 - 499) 413 mg{FEU}/L, Fibrinogen (NR: 3420 - 6480) 4736 umol/L, Folate within normal limits, HIV test unremarkable, Helicobacter test unremarkable, Hematocrit 0.45 (normal range 0.40-0.5), Hemoglobin (NR: 130 - 170) 150 g/L, Heparin-induced platelet antibody negative and no evidence of thrombosis, effectively ruling out VITT and finalizing a diagnosis of ITP, IgG ELISA results of IgG antibodies against platelet factor-4 (PF4) were negative with 0.131 OD (optical density normal range <0.400 OD) ; International normalized ratio (INR) was 1.1, Laboratory test Peripheral smear revealed normal morphology of neutrophils and monocytes, with small and mature lymphocytes, normocytic normochromic red blood cells without significant anisopoikilocytosis, severe thrombocytopenia with normal platelet morphology, Leukocyte count (NR: 3.5 - 10.1) 6.8 10*9/L, Liver function test unremarkable, MCH (NR: 28 - 33) 31 pg/{cells}, MCHC (NR: 32 - 36) 31 g/dL, MCV (NR: 80 - 100) 92 um3, Platelet count (NR: not provided) 8 10*9/L (190 x 10*9/L in years prior to vaccine), Platelet count (NR: 150 - 400) 8 10*9/L, Prothrombin time (NR: 9.2 - 13.5) 12 sec, Red cell distribution width (NR: not provided) 12 %, Renal function test unremarkable, Reticulocyte count (NR: 21 - 100) 86 10*9/L, Reticulocyte count immature reticulocyte fraction was 0.07 (normal range 0.01-0.16), TSH unremarkable, Ultrasound abdomen revealed patent hepatic vasculature and unremarkable liver and spleen, with spleen measuring 11.4 cm in length. A normal-sized spleen and patent hepatic vasculature, ruling out hepatic vasculopathy or hypersplenism, Vitamin B12 within normal limits and Von Willebrand aposs factor antigen test was 5 at admission. Treatment medications (dates unspecified) included: prednisone, and dexamethasone. He was transfused with one unit of apheresed platelets with a minimum of 2.9 x10*11 platelets and started on dexamethasone 40 mg daily for four days in the setting of high suspicion for ITP. Heparin products were avoided during the investigations. The patient was discharged from the hospital to complete his last planned dose of dexamethasone 40 mg PO at home that evening. Based on available outpatient medical records across 48 days since hospital discharge, the patient had close follow-up with his primary care physician and hematology/oncology. Unfortunately, he had relapse of thrombocytopenia and was again started on prednisone with slow taper course, but at the time of this writing, was deemed steroid dependent and Hematology/oncology was planning to initiate a thrombopoietin receptor (TPO) agonist. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of immune thrombocytopenia was not reported. The authors concluded that this was an early case of ITP following the administration of the Janssen Ad26.CoV2.S immunization at the time of presentation. There has only been one reported case of isolated thrombocytopenia without thrombosis since. Certainly, there is no definitive evidence to argue that this was not an initial episode of primary ITP coincidentally surrounding the immunization administration. Strikingly, the timeline of events, as well as the thorough workup to exclude other secondary causes leads them to believe that the Janssen Ad26.CoV2.S immunization caused secondary ITP in this patient. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0:20220820129- covid-19 vaccine ad26.cov2.s - Immune thrombocytopenia. This event(s) is labeled per RSI and is therefore considered potentially related.