K18-hACE2 mice are a lethal murine model for SARS-CoV-2 with infectious features in the lung that are similar to those of severe human COVID-19 (53, 54).To further evaluate the protective efficacy against SARS-CoV-2 in vivo, we routinely intranasally immunized transgenic hACE2 mice three times with 10 μg RBD-mFc protein formulated with alum adjuvant (n=8) and PBS as a control (n=8) (Figure 7A). The gene discussed is KRT18; the disease is COVID-19.