During dynamic monitoring of antibody for 16 patients with COVID‐19, it was found that the serological transformation of IgM and IgG antibodies in the samples could be divided into three modes: The first was the simultaneous transformation of the two; the second was that the transformation of IgM in serum was earlier than IgG; the third was that the transformation of IgG in serum was earlier than IgM. The gene discussed is CD40LG; the disease is COVID-19.