The primary manifestation of COVID-19 is diffuse alveolar injury, accompanied by numerous lung epithelial cells which are proliferating, atrophic, exfoliating, or squamous metaplasia in acute phase, which result in the destruction of the alveolar epithelial barrier, massive lung exudation and the large release of the KL-6 28, 29. The gene discussed is MUC1; the disease is COVID-19.