We further sought to determine if the levels of activin A, its pathway marker FLRG as it is activin A activation of Smad2/3 (10) activin B, FLRG, and PAI-1 correlated with important disease markers of COVID-19, such as disease severity, the requirement for supplemental oxygen, other signs of ARDS, and mortality. The gene discussed is SERPINE1; the disease is COVID-19.