ACE2 and infection: Class 1 and 2 antibodies develop early after infection or mRNA immunization and are generally more potent than classes 3 and 4, because they interfere directly with the interaction between the SARS-CoV-2 RBD and its cellular receptor ACE2 (Barnes et al., 2020a; Muecksch et al., 2021; Wang et al., 2021b).