ACE2 and COVID-19: In this analysis as well, plasma ACE2 in COVID-19 patients was significantly elevated in patients with outcome category A2 (intubated and survived) compared with outcome categories A3-A4 (not intubated) at the time of blood sampling at day 0, day 3, and day 7 (P = 0.0016, P < 0.0001, and P < 0.0001, respectively) (S1 Fig).