PF4 and Thrombocytopenia: After two studies demonstrated that, in Vaxzevria recipients, venous thrombotic events [cerebral venous thrombosis (CVT), splanchnic venous thrombosis, and/or other thromboses] are observed in association with platelet aggregation, thrombocytopenia and antibodies to platelet factor 4 (PF4) (27, 28), such event was called vaccine-induced immune thrombotic thrombocytopenia (VITT).