CD40LG and viral infectious disease: Analyzing the anti-SARS-CoV-2 antibody response in detail for eight MIS-C patients showed all eight had IgG and IgA antibodies but lacked IgM antibodies consistent with MIS-C developing weeks after virus infection occurred (Figure 1I) (Castagnoli et al., 2020; Hoang et al., 2020; Hoste et al., 2021).