CD40LG and COVID-19: Previous studies have demonstrated positive associations between the clinical severity of COVID-19 and variously measured antibody responses, including the neutralizing antibody titers (8, 10, 17, 20, 21, 26, 28, 31, 34–37), total antibody titers (9, 27, 36), IgG titers (10, 12–14, 16, 18, 22, 28–30, 32, 33), IgM titers (10, 11, 22–24, 32), and/or IgA titers (10, 13, 18, 19, 22, 29, 32).