First, it is a real-world approach and included the largest cohort of serum anti-SARS-CoV-2 IgM/IgG antibodies levels and the relationship with vaccination in non-COVID-19-infected population ever evaluated in the literature, which reflected objectively the real status of the serum anti-SARS-CoV-2 IgM/IgG antibody. Here, CD40LG is linked to COVID-19.