Semin Thromb Hemost 2022; 48(01): 015-018
DOI: 10.1055/s-0041-1735453

COVID-19 Vaccine-Induced Immune Thrombosis with Thrombocytopenia (VITT) and the Shades of Grey in Thrombus Formation

Jecko Thachil
1   Department of Haematology, Manchester University Hospitals, Oxford road, Manchester, United Kingdom
› Author Affiliations

Historically, two types of clots have been described in the medical literature—the so called “white clot,” where the platelets appear to dominate, and the so called “red clot,” where fibrin network with trapped red cells represents the main elements of the thrombi. A vessel-based distinction has also been chronicled where platelet-rich clots occur in arterial thrombosis while activation of coagulation factors is proposed to cause venous thrombosis.[1] Accordingly, antiplatelet drugs are the treatment of choice where arterial thrombosis occurs, whereas anticoagulants are the typical drug therapy in venous thrombosis. In 2021, vaccine-induced immune thrombocytopenia and thrombosis (VITT) has been proposed to occur as a result of vaccination against COVID-19 (coronavirus disease 2019) with adenovirus-based vaccines. This represents a serious thrombotic disorder where both platelets (evident in thrombocytopenia) and coagulation factors (associated decreased fibrinogen and raised D-dimers) are likely to play a significant role.[2] [3] [4] With both platelets and the clotting system involved, can VITT provide clues to the observed shades of gray (rather than a clear red and white distinction) often seen in thrombus formation? Should we consider more than just antiplatelets or anticoagulants in treating or preventing extension of thrombus formation in the future?

Publication History

Article published online:
08 October 2021

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