As neutrophil-derived extracellular traps (NETs) have been reported to be induced by SARS-CoV-2 infection and associated with lung tissue damage (lung epithelial apoptosis) in COVID-19 patients (59), it would be interesting to investigate whether NETs contribute to the higher disease (Pdisease = 0.0578) and cell infiltration (Plung cell infiltration = 0.0829) in the lungs of Delta-infected K18-hACE2 mice. This evidence concerns the gene KRT18 and COVID-19.