S100A9 and COVID-19: Within both COVID-19 cohorts, independent of the occurrence of thromboembolic outcome, inflammatory-related proteins (eg, leucine-rich α2-glycoprotein 1, S100A8, S100A9, CRP, and SAA1), von Willebrand factor (VWF) and neutrophil-related proteins (eg lactotransferrin, myeloperoxidase, and neutrophil defensin 1) were increased in abundance compared with healthy controls (Supplementary Figure S3, Supplementary Table S1G).