For 336 patients with COVID-19 infected by delta variant of SARS-CoV-2 in Yangzhou, 120 patients were unvaccinated and among them, 77.5% patients produced no SARS-CoV-2-specific antibody, 10.8% patients produced IgG only, 1.7% patients produced IgM only, and 10.0% patients produced IgG + IgM (Figure 2). This evidence concerns the gene CD40LG and COVID-19.