An interesting observation was a significant, moderate negative correlation between cystatin C and total cholesterol in each of the time-points in the COVID-19 group (C1: Rs = −0.51, p < 0.01; C7: Rs = −0.52, p < 0.01; C14: Rs = −0.65, p < 0.01; C28: Rs = −0.66, p < 0.01). This evidence concerns the gene CST3 and COVID-19.