Simpler models such as K18-hACE2 may be more useful for investigating chronic multiorgan complications since the K18 promoter allows for the expression of hACE2 in airway epithelial cells as well as epithelia of other extrapulmonary organs [117]; however, the infectious dose of SARS-CoV-2 should be considered to avoid lethal encephalitis and outcome [78,79,116]. Here, KRT18 is linked to encephalitis.