Furthermore, in terms of the expression and distribution of CRGs, CEACAM1, CEACAM3, CEACAM5, CEACAM6, CEACAM7, CEACAM8 and CEACAM21 were differentially expressed among moderate, severe/critical COVID-19 patients and healthy controls while CEACAM5 and CEACAM6 were significantly localized in the type II pneumocytes of COVID-19 patients (Fig. 4D–E). The gene discussed is CEACAM5; the disease is COVID-19.