We first analyzed the major PB populations (i.e., lymphocytes, monocytes, and granulocytes) and noticed that mean percentages of lymphocytes and granulocytes differed significantly (ranging in statistical significance from p < 0.05 to p < 0.001) between active COVID-19 patients and the three groups of recovered CP donors and controls (Figure 1A). Here, CP is linked to COVID-19.