Therefore, samples obtained from hospitalized patients were categorized as ordinary cases (n = 141, No. tested = 280) and severe cases (n = 23, No. tested = 58) (severe cases + critically ill cases) based on the Diagnosis and treatment of novel coronavirus pneumonia (Trial version 6). As shown in Figure 4(A and B), the investigators compared the IgM and IgG concentrations between the groups of ordinary and severe cases (severe cases + critically ill cases) within the first three weeks (day 0∼21) and at three weeks (>day 21) after COVID-19 onset. Here, CD40LG is linked to pneumonia.