DCN and COVID-19: decorin levels in the control group were 43.36 ± 1.14 ng/mL, which significantly decreased in patients with moderate COVID-19 (40.24 ± 0.64 ng/mL) and further decreased in severe COVID-19 patients (35.49 ± 1.00 ng/mL), with an ANOVA p value of 0.0059.