THROMBOSIS; THROMBOCYTOPENIA; This spontaneous report was received from literature. This report concerned a female in her fourth decade,  race and ethnic origin not provided.  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, intramuscular, batch number was not reported) dose, start therapy date were not reported for prophylactic vaccination  The batch number was not reported, and has been requested. No concomitant medications were reported.  Ten days after receiving Ad26.COV2.S Janssen vaccine, the patient developed headaches followed by thrombocytopenia (platelet 80 10*3/uL) and worsening head and neck pain 15 days after vaccination. Head CT was negative for acute infarct or hemorrhage but demonstrated subtle increased density of the right transverse and sigmoid sinuses suspicious for dural venous sinus thrombosis. A week later, she developed left lower extremity pain and weakness. Duplex ultrasound demonstrated acute deep venous thrombosis involving posterior tibialis and popliteal veins. Magnetic resonance venography and CT venography was performed and demonstrated a large near occlusive thrombus in the right transverse sinus extending to the right sigmoid sinus and jugular bulb (empty delta sign'). A direct thrombin inhibitor (argatroban) was initiated and the patient was transferred to a tertiary care center with the clinical diagnosis of vaccine-induced thrombotic thrombocytopenia (VITT) (coded as thrombosis and thrombocytopenia). On admission, the platelet count had improved to 143 10*3/uL.  Heparin PF4- IgG (immunoglobulin G) antibody was positive. The patient received bivalirudin with a rise of the platelet count to 180 10*3/uL and improvement in headache.  Intravenous immunoglobulin was not given due to the improvement in platelet count. The patient was discharged home on apixaban. One week later, she developed chest pain and CT angiography of the chest demonstrated subsegmental pulmonary emboli with no heart strain. Duplex ultrasound showed resolution of left popliteal vein thrombosis suggestive of clot embolization. Repeat CT venogram demonstrated improvement in dural venous sinus thrombosis with a decrease in clot burden.  The patient was instructed to continue apixaban. The action taken with covid-19 vaccine ad26.cov2.s was not applicable. The outcome of the vaccine-induced thrombotic thrombocytopenia (coded as thrombosis and thrombocytopenia) was not reported. This report was serious (Hospitalization Caused / Prolonged).; Sender's Comments: V0: This spontaneous report received from literature concerned a female in her 30's, unknown ethnicity, who had thrombocytopenia and thrombosis 15 days and around 22 days, respectively, after receiving the Janssen COVID-19 vaccine. Patient's height and weight were not reported. Medical history and concomitant medications were not reported. Condition started with headaches 10 days post vaccine. Headaches were worsening and, until 15 days post vaccine, the patient also felt neck pain and was noted to have thrombocytopenia (platelet count 80 x 10*3/uL). Head CT was suggestive of dural venous sinus thrombosis.  One week later (around 22 days post vaccine), she felt pain and weakness on her left lower extremity. Duplex ultrasound showed deep venous thrombosis involving posterior tibialis and popliteal veins. Magnetic resonance venography and CT venography showed thrombus in the right transverse sinus extending to the right sigmoid sinus and jugular bulb. The patient was diagnosed with vaccine-induced thrombotic thrombocytopenia (VITT); argatroban was initiated. She was transferred to a tertiary care center. Upon admission, the platelet count was 143 10*3/uL and heparin PF4- IgG antibody was positive. The patient's platelet count further increased to 180 10*3/uL and headache improved. Medication was shifted to bivalirudin. Improvement continued and patient was discharged on apixaban. One week from discharge, patient experienced chest pain. CT angiography of the chest showed subsegmental pulmonary emboli with no heart strain. Repeat duplex ultrasound showed resolution of left popliteal vein thrombosis and repeat CT venogram showed improvement in dural venous sinus thrombosis. The patient continued on apixaban. Based on evolving knowledge of Thrombosis with Thrombocytopenia Syndrome (TTS, per definition), the low platelet count and temporal relationship to vaccination, the events are assessed to have a plausible relationship with vaccination.