PF4 and Venous thrombosis: The diagnosis of VITT is multimodal and typically confirmed if the following criteria are met: onset of symptoms 5–30 days after vaccination against SARS-CoV-2; presence of thrombosis; thrombocytopenia (platelet count < 150,000 per cubic millimeter); d-dimer level > 4000 FEU; positive anti-PF4 antibodies on ELISA [18].