SERPINE1 and COVID-19: In the present study, PAI-1 levels were lower in the mice with SARS-CoV-2 infection than with LPS-induced sepsis, although increase in PAI-1 levels in both models was statistically significant and was more than equivalent to that seen in severe COVID-19 patients requiring hospitalization compared to healthy controls30; the peak PAI-1 levels were 258.2 ng/mL after LPS injection (0.5 × LD50) and 10.8 ng/mL after mouse-adapted SARS-CoV-2 infection (almost 1.0 × LD50).