Multifaceted roles of Fcγ receptors in COVID-19 and vaccine responses.

Recent data have revealed various effector functions of FcγRs in immune responses against challenges with SARS-CoV-2 virus. FcγRs act as a bridge between antibody specificity and effector cells. In many cases, IgG/FcγR interactions generate cell-mediated immune protection from infection via ADCP or ADCC. These responses are beneficial, as they may participate in virus elimination and persist longer than neutralizing anti-Spike antibodies. In contrast, these interactions may sometimes prove beneficial to the virus by enhancing viral uptake into phagocytic cells via ADE and causing excessive inflammation. Here, we summarize key features of FcγRs, discuss effector functions, clinical relevance, and factors influencing FcγR-mediated immune responses in COVID-19 and vaccine responses, and consider IVIg and kinase inhibitors for targeting FcγRs signaling in COVID-19.