Although most of the participants (58.5%; n = 234/400) did not previously experience COVID-19-like symptoms, 49.1% (n = 115/234) and 25.6% (n = 60/234) of them were anti-SARS-CoV-2 IgM-positive and anti-SARS-CoV-2 IgG-positive, respectively. Here, CD40LG is linked to COVID-19.