The dendograms were built based on the clustering metric “Euclidean” and the method “complete,” in which we found the following 9 neighboring factors around COVID-19 severity: D-dimer, fibrinogen, CRP, LDH, WBC count, number of neutrophils, glucose, scoring index of chest x-ray, and ferritin (Figures 4 and 5). Here, CRP is linked to COVID-19.