TREM1 and COVID-19: In both COVID-19(+) TV and COVID-19(-) PU control groups a gene expression signature associated with neutrophil activation and chemotaxis was expressed; however, these signatures were characterized by unique subsets of genes in COVID-19(+) TV (TREM1, CXCR1, CXCL8, and S100A12) and COVID-19(-) PU control (CXCL1, CXCL2, and CD177) groups (Figure 4B).