KITLG and respiratory tract infectious disorder: In accordance with a general inflammatory response in respiratory infections, 7 analytes (APRIL, sIL-2R, MIF, MIP-1b, SCF, SDF-1a, sTNF-RII) showed a significant increase in serum levels in both the CoV- and CoV+ group compared to the healthy control cohort (Figure 1 and Supplementary Material 3), while remaining statistically indifferent between CoV- and CoV+.