The most notable finding is that the patient-derived signature was able to perfectly classify the EpCAM-sorted epithelial fractions from the bronchoalveolar lavage fluids of infected and healthy subjects (ROC AUC 1.00; GSE145926-Epithelium Liao et al., 2020), suggesting that the respiratory epithelium is a major site where the host immune response is detected in COVID-19. This evidence concerns the gene EPCAM and COVID-19.