ABSTRACT
Coronavirus disease 2019 (COVID-19) encompasses a broad spectrum of clinical manifestations caused by infection with severe acute respiratory syndrome coronavirus 2.Patients with severe disease present with hyperinflammation which can affect multiple organs which often include observations of microvascular and macrovascular thrombi. COVID-19 is increasingly recognized as a thromboinflammatory disease where alterations of both coagulation and platelets are closely linked to mortality and clinical outcomes. Although platelets are most well known as central mediators of hemostasis, they possess chemotactic molecules, cytokines, and adhesion molecules that are now appreciated as playing an important role in the regulation of immune response. This review summarizes the current knowledge of platelet alterations observed in the context of COVID-19 and their impact upon disease pathobiology.