Finally, two members of the protein disulfide isomerase (PDI) family, PDIA6 and P4HB, which are critically responsible for thrombus formation (52), were significantly increased in COVID-19 patients compared to healthy controls (PDIA6 spot 1602: FC = 1.40; p = 0.002 and P4HB spot 1351: FC = 1.37; p = 0.0006). Here, P4HB is linked to COVID-19.