A sample seropositive for both IgM and IgG indicates that the subject’s immune system is actively producing antibodies against an ongoing infection that likely began more than 14 days ago, whereas a sample negative for both IgM and IgG indicates that the subject is not suspected of having COVID-19, since the immune system has not produced any antibodies to target the viral antigen [14]. This evidence concerns the gene CD40LG and COVID-19.