The phosphorylation of STAT1 after low‐dose IFN‐α or IFN‐γ stimulation for 48 h remained unchanged in healthy controls and mildly affected COVID‐19 patients, while it was enhanced in severely affected COVID‐19 patients already in unstimulated cells and without further increase after 48 h incubation with IFN‐α or IFN‐γ (Fig. 4B). Here, STAT1 is linked to COVID-19.