THROMBOTIC THROMBOCYTOPENIA; CEREBRAL VENOUS SINUS THROMBOSIS; SPLANCHNIC VEIN THROMBOSIS; PORTAL VEIN THROMBOSIS; INTRAPARENCHYMAL BRAIN HAEMORRHAGE; ABDOMINAL PAIN; BACK PAIN; NAUSEA; VOMITING; DEATH; This spontaneous report received from a consumer concerned multiple patients (6) of unspecified age and sex. The patients' height, and weight were not reported. No past medical histories or concurrent conditions were reported. The patients received covid-19 vaccine ad26.cov2.s (suspension for injection, route of admin not reported, batch number: Unk) dose, start therapy date were not reported for prophylactic vaccination. The batch numbers were not reported. The Company is unable to perform follow-up to request batch/lot numbers. No concomitant medications were reported. On an unspecified date, five patients presented with initial symptoms of headache and back pain in the sixth patient who subsequently developed headache (subsumed under CVST). It was reported that one patient also had abdominal pain, nausea, and vomiting. The four patients developed focal neurological symptoms focal weakness, aphasia, visual disturbance (subsumed under CVST) prompting presentation for emergency care. The median days from vaccination to hospital admission was 15 days (range 10 to 17 days). All were eventually diagnosed with cerebral venous sinus thrombosis (CVST) by intracranial imaging. The two patients were also diagnosed with splanchnic and portal vein thrombosis. It was unusual for patients presenting with thrombotic events, all six patients showed evidence of thrombocytopenia (less than 150,000 platelets per microliter of blood), consistent with a condition known as thrombotic thrombocytopenia, with platelet nadir counts ranging from 10,000 to 127,000 during their hospitalizations. It was reported that four patients developed intraparenchymal brain hemorrhage and one subsequently died. Laboratory data (dates unspecified) included: Imaging procedure (NR: not provided) Cerebral Venous Sinus Thrombosis, and Platelet count (NR: not provided) ranging from 10000 to 127000. On an unspecified date, one patient died from unknown cause of death. It was unspecified if an autopsy was performed.  The outcomes for the multiple patients with cerebral venous sinus thrombosis, thrombotic thrombocytopenia, back pain, abdominal pain, nausea, vomiting, splanchnic vein thrombosis, portal vein thrombosis and intraparenchymal brain haemorrhage was not reported. This report was serious (Death, and Hospitalization Caused / Prolonged). This case, from the same reporter is linked to 20210340967.; Sender's Comments: V0: 20211138044- covid-19 vaccine ad26.cov2.s-thrombotic thrombocytopenia, Cerebral venous sinus thrombosis, splanchnic vein thrombosis, portal vein thrombosis. This event(s) is labeled per RSI and is therefore considered potentially related. 20211138044- covid-19 vaccine ad26.cov2.s-Death, intraparenchymal brain haemorrhage. This event(s) is considered unassessable. The event(s) has a compatible/suggestive temporal relationship, is unlabeled, and has unknown scientific plausibility. There is no information on any other factors potentially associated with the event(s).; Reported Cause(s) of Death: UNKNOWN CAUSE OF DEATH