NEJM VITT review 237 suspected from 24 million Oxford-Astra Zeneca doses, incidence at least 1:100,000 >50 years, 1:50,000 <50 years, occurs 5-30 days after first dose. Extensive thrombotic sites, cerebral venous thrombosis dominant. Low platelets, increased D-dimer, reduced fibrinogen associated worse outcomes. Overall case fatality rate 23%, highest in patients with both ICH and platelet count below 30,000. No therapeutic options proven effective, although IVIG, corticosteroids, plasma exchange, and non-heparin anticoagulation are used.