The rapid spread of the Omicron variant is mainly due to its immune evasion ability, which is responsible for the infection of vaccinated and previously infected individuals.42 In addition, changes in cell entry and cellular tropism in the Omicron variant may also facilitate rapid transmission.27,28,31,43 Moreover, the Omicron variant has been shown to cause more asymptomatic infections than the other variants, which may contribute to the silent spread of the virus.44 Furthermore, the binding affinity of Omicron RBD to ACE2 contributes to transmission, but is not a major factor. This evidence concerns the gene ACE2 and infection.