IP-10 was upregulated in severe COVID-19 patients (199.2 pg/mL ± 82.6 pg/mL), but we found no difference between mild patients (51.7 pg/mL ± 39.4 pg/mL) and healthy controls (37.1 pg/mL ± 3.1 pg/mL) (Fig. 1b). Here, CXCL10 is linked to COVID-19.