The attenuation of the SARS-CoV-2 vaccine strain (designated as SARS-CoV-2/human/Korea/CNUHV03-CA22 °C/2020) and its efficacy as a vaccine was confirmed in hACE-2 transgenic mice (K18-hACE2 mice), to which infections by SARS-CoV and SARS-CoV-2 are lethal [28,29,30,31,32]. The gene discussed is KRT18; the disease is infection.