Although most blood neutrophils stained positive for CXCR1 and CXCR2, the relative expression levels of these chemoattractant receptors were significantly lower on blood neutrophils from patients with COVID-19 compared with blood neutrophils from healthy controls (Figure 3, A and B; and Supplemental Figure 1, C and D). Here, CXCR1 is linked to COVID-19.