LAUSR

Objectives This study aimed to explore the regularity of S-RBD domain antibody reactivity after immunization with inactivated SARS-CoV-2 vaccine and evaluate the immune response effect of this vaccine. Design or methods Venous blood samples were collected from 1156 healthcare workers who participated in the phase III clinical trial of SARS-CoV-2 inactivated vaccine. The S-RBD domain antibody levels in serum were detected by ELISA 14 days after the first and second active immunization respectively. Results The positive rate of S-RBD domain antibody against SARS-CoV-2 was 28.03% and 86.76% respectively after inoculation of the first and second vaccination. The mean inhibition rate of S-RBD domain antibody against positive samples was (57.18 ± 18.87) % after the second vaccination at 14 days. Gender and age had no effects on the positive rate. The positive rate was decreased in the high BMI group. Single-factor logistic analysis showed that there was no significant correlation between age and positive rate. BMI was negatively correlated with the positive rate. Conclusions After two times of immunization, the positive rate of SARS-CoV-2 S-RBD domain antibody was high, and the vaccine had good immunogenicity. The improvement of the immune strategy should focus on the effects of BMI and other factors.