K18-hACE2 mice inoculated intranasally with SARS-CoV-2 (n = 50 [n = 28 male and n = 22 female]) began losing weight as early as 4 days post-infection (dpi) irrespective of dose (1 × 104 or 1 × 106 PFUs) and sex, with maximum weight loss occurring at 6–7 dpi (15.9 ± 1.1% in male mice, 19.7 ± 1.6% in female, and combined 17.8 ± 2.4%; Figure 1A). This evidence concerns the gene KRT18 and infection.