VACCINE INDUCED THROMBOTIC THROMBOCYTOPENIA; PULMONARY EMBOLISM; CEREBRAL VENOUS SINUS THROMBOSIS (CVST); SPLANCHNIC VEIN THROMBOSIS; This spontaneous report was received from literature. This report concerned a 28 year old male of an unspecified race and ethnic origin. The objective of this study was to study COVID-19 vaccinated individuals develop anti-platelet factor 4 (PF4) antibodies that cause thrombocytopenia and thrombotic complications, a syndrome referred to as vaccine induced immune thrombotic thrombocytopenia (VITT). The patient's height, and weight were not reported. No past medical history or concurrent conditions were reported. The patient received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: Unknown and expiry: Unknown) dose, start therapy date were not reported, 1 total was administered for prophylactic vaccination. The batch number was not reported and has been requested. No concomitant medications were reported.  On an unspecified date, the patient experienced vaccine induced thrombotic thrombocytopenia (VITT), pulmonary embolism (PE), cerebral venous sinus thrombosis (CVST), and splanchnic vein thrombosis, and was hospitalized (date unspecified). It was also reported that the timing of symptom onset after vaccination was 10 days. Laboratory data (dates unspecified) included: Blood sample was obtained. PF4-polyanion enzyme linked immunosorbent assays (ELISA) was positive (Optical Density was greater than 1.0) (there were persistent anti-PF4 antibodies for 6 months during follow ups), Fibrin D dimer was elevated (22,546 ng/mL FEU) and reference range was less than 500 ng/mL, Platelet count (NR: 9000 - 126000) 66,000 /uL, and Serotonin release assay (SRA) (Normal Range - less than 20 percent serotonin release) result was negative. The p-selectin expression assay (PEA) was performed. The PF4-dependent p-selectin expression assay that uses platelets treated with PF4 rather than heparin consistently diagnosed Ad26.COV2.S-associated VITT. Most Ad26.COV2.S-associated VITT antibodies persisted for greater than 5 months in PF4-polyanion ELISAs, while the PEA became negative earlier. Normal Range for P-selectin expression was less than 19 percent. A new laboratory test was done for the sensitive and specific detection of VITT antibodies, using un-complexed PF4. Treatment medications (dates unspecified) included: argatroban, intravenous immunoglobulinG (IVIg) and apixaban. Patient were treated with high-dose intravenous immunoglobulinG and a direct thrombin inhibitor during the acute episode. The number of days hospitalized and discharge information was not provided. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of the pulmonary embolism, cerebral venous sinus thrombosis (CVST), splanchnic vein thrombosis and vaccine induced thrombotic thrombocytopenia (VITT) was not reported. The authors emphasized that the associated VITT antibodies persisted for greater than 5 months in platelet factor 4 (PF4) polyanion enzyme linked immunosorbent assays (ELISA) while the PEA became negative earlier. Thus, it was concluded that the patients with VITT demonstrate long term ELISA positivity, although functional assays become seronegative earlier during the course of recovery. The data suggest that the uncomplexed PF4 ELISA is sensitive and significantly more specific for the detection of VITT than currently available tests. This report was serious (Hospitalization Caused / Prolonged). This case, from Same Literature article is linked to 20220237634, 20220249398, 20220249417, 20210448310, 20210444498, 20210415297, 20220249430 and 20220249503.; Sender's Comments: V0- 20220249472-Covid-19 vaccine ad26.CoV-2.s-Vaccine induced thrombotic thrombocytopenia, Pulmonary embolism, Cerebral venous sinus thrombosis, Splanchnic vein thrombosis. This event(s) is labeled per RSI and is therefore considered potentially related.