PF4 and Thrombocytopenia: Following the UK Haematology Expert Group consensus [7] and World Health Organization (WHO) recommendations [6], VITT typically occurs five to thirty days post-vaccination and is clinically characterized by thrombocytopenia, strongly elevated D-dimer levels, the ability of anti-PF4 antibodies to activate platelets and the occurrence of thrombosis in atypical sites such as cerebral venous sinus and/or splanchnic veins [8].