For example, a complete blocking of ACE2 receptor could not inhibit infection in certain cell types owing to the reported ACE2-independent receptor.115 Moreover, some extracellular proteases or cell type-specific lysosomal proteases could compensate for the lack of furin or TMPRSS2.21 Therefore, effective treatment options will need extensive clinical trials and post-approval monitoring. Here, ACE2 is linked to infection.