The scatter plot distribution of individual values showed that decreased levels of PDGF (cut-off = 94 pg/mL; Se=89%; Sp=93%) and increased levels of IFN-γ (cut-off=4.2 pg/mL; Se=94%; Sp=86%) and IL-6 (cut-off=0.3 pg/mL; Se=84%; Sp=93%) on hospital admission (D0) were able to correctly differentiate the COVID-19 patients from the healthy control patients (Figure 7A). Here, IL6 is linked to COVID-19.