In the control group, CPA3+ cells were found throughout the alveolar–capillary interstitial tissue (Figure 3a,b), whereas in COVID-19 patients, these cells were in areas with abundant leukocyte infiltration (Figure 3c), in the wall of thrombotic vessels (Figure 3d), and in areas with fibrosis (Figure 3e). The gene discussed is CPA3; the disease is COVID-19.