KRT18 and infection: In agreement with our observations and those of Essaisi-Laziosi et al. [19], Achdout et al. reported that the sequential infection of transgenic mice expressing the human angiotensin-converting enzyme 2 (ACE2) under a cytokeratin 18 promoter (K18-hACE2) with influenza A virus and SARS-CoV-2, 48 h apart, resulted in a significant decrease in SARS-CoV-2 viral loads in the lungs and nasal turbinates [28].