Other reported hACE2 humanized mice express the transgene under: (i) murine ACE2 promoter, without reported hACE2 mRNA expression in the brain (Yang et al, 2007), (ii) “hepatocyte nuclear factor‐3/forkhead homologue 4” (HFH4) promoter, i.e., “HFH4‐hACE2” C3B6 mice, in which lung is the principal site of infection and pathology (Menachery et al, 2016; Jiang et al, 2020), and (iii) “CAG” mixed promoter, i.e. “AC70” C3H × C57BL/6 mice, in which hACE2 mRNA is expressed in various organs including lungs and brain (Tseng et al, 2007). The gene discussed is ACE2; the disease is infection.