RBD is the main target of neutralizing antibodies (NAbs) which can be isolated from plasma of COVID-19 patients, immunoglobulin libraries, or immunized laboratory animal models.1 These NAbs can be roughly divided into four main classes, of which class 1s′ and class 2s′ RBD epitopes overlap with the ACE2-binding site, suggesting a neutralization mechanism that involves direct competition with ACE2. The gene discussed is ACE2; the disease is COVID-19.