Meanwhile, we analyzed the serum antibody results of 105 patients with COVID‐19 confirmed by nucleic acid test, and found it was great possibe that antibody detection was negative within 0–5 days for patients infected with SARS‐CoV‐2 virus, IgM liter would increase significantly after 1 week, and IgG liter reached a peak within 15‐21 days. This evidence concerns the gene CD40LG and COVID-19.