One study that examined the kinetics of SARS-CoV-2 antibodies in COVID-19 infections [25] has shown that IgM does increase in the first week after symptom onset (seropositivity rate of 75%), but this elevation becomes blunted by the second week of infection (IgM seropositivity increasing to 84.2%, IgG to 94.7%) and declines thereafter. This evidence concerns the gene CD40LG and infection.