CD40LG and COVID-19: At the peak of the antibody response, 15–28 days after symptoms onset, anti-RBD IgM and IgA were increased in 77% (40/52) and 85% (44/52) of convalescent patients, respectively, but rapidly decreased between 1 and 3 months and were detected in less than 4.5% (2/44) and 11% (5/44) of patients tested between 6 and 15 months when assessing all COVID-19 subjects by cross-sectional analysis (Figures 2A, 2B, 2D, and 2E).