For example, during infection with some viruses such as Adenovirus Coxsackievirus-B and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), protease-activated receptors (PARs) such as PAR1 and PAR2 can regulate coagulation as an immune response to the infections since PAR1 positively regulates the expression of protein prothrombotic factors such as VWF and P-selectin and platelet factor 4 of endothelial cells [51,52] and the expression of tissue factor (TF) via the detection of the presence of the intracellular viral genome [66]. Here, PF4 is linked to infection.