A review on suggested mechanisms in thrombocytopenia and thrombosis following ChAdOx1 nCoV-19 vaccination

ABSTRACT

Background: ChAdOx1 nCov-19 vaccine is a viral vector-based vaccine with desirable protection (about 70.4%, two weeks after the second dose). Few reports were released on thrombocytopenia associated with thrombotic events shortly after the ChAdOx1 nCov-19 vaccination. However, the exact pathophysiologic mechanism of this vaccineinduced thrombotic complication has not yet been elucidated. Vaccine-induced thrombotic thrombocytopenia syndrome (VITTS) is associated with detecting anti-platelet factor 4 (PF4) antibodies that are not yet linked to previous exposure to heparin. Materials and Methods: In the current review, based on relevantly reported cases, possible mechanisms are suggested on the relationship between the anti-platelet factor 4 (anti-PF4) antibody assays, previous exposure to heparin, and the involved mechanisms of post-vaccination thrombocytopenia and thrombotic events, which might help the experts for selecting the appropriate therapeutic measures.