CD27 and COVID-19: We found a significantly increased STAT1 protein expression in all analyzed cell subsets from whole blood analysis, including T cells (CD4+ and CD8+), B cells (IgD+CD27− (Naïve), IgD+CD27+ (PreSwitched), IgD−CD27+ (PostSwitched), and IgD−CD27− (double negative), plasmablasts (CD20lowCD27high), and monocytes (CD14+) from all patients with COVID‐19 compared to healthy controls (Fig. 1C‐E).