A higher titer of total antibodies was independently associated with a worse clinical outcome of patients with COVID-19, and was significantly quicker than that of IgM and IgG.38 In another study, within 19 days after symptom onset, 100% of patients tested positive for antiviral IgG.39 Nicol et al.40 reported that the sensitivity for IgG detection, >14 days after onset of symptoms, was 100%, and the specificity was also excellent for IgG; however, the specificity was significantly different between IgA (78.9%) and IgM (95.8%). This evidence concerns the gene CD40LG and COVID-19.