High avidity of vaccine-induced immunoglobulin G against SARS-CoV-2: potential relevance for protective humoral immunity

Avidity of immunoglobulin G (IgG) is defined as its binding strength to target antigen. As a consequence affinity maturation the IgG response, avidity maturing well. Therefore, acute infections are characterized by low-avidity IgG, whereas past usually associated with high-avidity IgG. also observed optimal vaccination. has been shown play significant role in protective humoral immunity many microbial systems. After severe respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, situation different compared other viral infections, moderate degree reached most cases infection similar that after only one vaccination step. In contrast, two steps lead much higher directed towards spike protein S1 (S1) majority vaccinated individuals. it seems allow for more extended affinity/avidity than natural infection. The heterogeneous. It can be further enhanced third Complete depend on sustained availability antigen during process. Variants concern seem increase their receptor-binding domain (RBD) angiotensin-converting enzyme-2 (ACE2) and/or decrease susceptibility neutralizing antibodies. Classical neutralization tests do not necessarily reflect they operationally dissect reaction between and from ACE2. This approach fades out critical competition reactions ACE RBD S1. Quantitative determination might an essential tool define individuals possess suboptimal therefore benefit additional booster immunization.