Importantly, there were no differences between VITT-CVT non-ChAdOx1-S vaccine group and unvaccinated pre-COVID-19 CVT group for well-established risk factors for CVT including lupus anticoagulant, antiphospholipid antibodies, Protein-C deficiency, Protein-S deficiency, antithrombin deficiency, factor VIII (FVIII), Factor-V Leiden and prothrombin G20210A. Here, F2 is linked to protein S deficiency.