CD40LG and COVID-19: In a first set of experiments, we measured IgG, IgG subclasses, IgM, and IgA levels specific for folded S and RBD in the complete population of COVID‐19–convalescent patients (mild: n = 139; severe; n = 114) and in the 235 control subjects by ELISA (Figure 1A, Figure S1A‐B).