CD40LG and infection: In a study [71], on the humoral memory response of SARS-CoV-2 in patients at 1.3 months and 6.2 months after infection, IgM showed the greatest reduction in anti-RBD reactivity (53%), followed by anti-RBD IgG (32%), anti-RBD IgA (15%), and anti-N IgG (22%).