How immune, clotting factors could increase the risk for Covid-19

The complement cascade as part of the body's immune system helps antibodies clear pathogens, and a new study finds that this component of immunity may also play a role in who gets sick — and how severely — with Covid-19. Researchers looked at data from more than 11,000 patients hospitalized for Covid-19 at NewYork-Presbyterian/Columbia University Irving Medical Center and found that nearly a quarter of these patients who also had age-related macular degeneration, which is an illness known to arise when the complement system is dysfunctional, died. A separate analysis of patient data in the U.K. Biobank also found that a history of clotting disorders such as thrombosis — and mutations in genes linked to clotting — seemed to carry a higher risk for hospitalization as a result of Covid-19. The data don't show a causal link, but suggest that therapies that target the complement system and coagulation may be helpful to Covid-19 patients.