ISTH Academy

Abstract
COVID‐19 is predicted to overwhelm healthcare capacity in the US and worldwide and as such interventions that could prevent clinical decompensation and respiratory compromise in infected patients are desperately needed. Excessive cytokine release and activation of coagulation appear to be key drivers of COVID‐19 pneumonia and associated mortality. Contact activation has been linked to pathologic upregulation of both inflammatory mediators and coagulation and accumulating preclinical and clinical data suggest it to be a rational therapeutic target in COVID‐19 patients. Pharmacological inhibition of the interaction between coagulation factors XI and XII has been shown to prevent consumptive coagulopathy, pathologic systemic inflammatory response, and mortality in at least 2 types of experimental sepsis. Importantly, inhibition of contact activation also prevented death from S. aureus‐induced lethal systemic inflammatory response syndrome in nonhuman primates. The contact system is likely dispensable for hemostasis, and may not be needed for host immunity, suggesting it to be a reasonably safe target that will not result in immunosuppression or bleeding. As a few drugs targeting contact activation are already in clinical development, immediate clinical trials for their use in COVID‐19 patients are potentially feasible for the prevention or treatment of respiratory distress.