Although the proportion of SARS-CoV-2-positive cells in BALF was relatively similar (Figure 1E and Supplementary Figure 1D), we found only two consensus genes from different cell types—one for the N gene of the virus and the other for the CTSL gene (Figure 1F)—when we compared the differential gene expression in COVID-19-positive to -negative cells. The gene discussed is CTSL; the disease is COVID-19.