In this study, three measurements were used to investigate the antibody responses of SARS-CoV-2 generated by two doses of inactivated COVID-19 vaccine: the titers of neutralizing antibodies to live SARS-CoV-2, the titers of neutralizing antibodies to pseudovirus, and the titers of IgG and IgM specific for the S protein and N protein of SARS-CoV-2. This evidence concerns the gene CD40LG and COVID-19.