ObjectiveTo investigate the antibody concentration and immune status of intensive care medical staff after vaccination against COVID-19. Methods From October 1, 2021 to February 28, 2022, the serial numbers of 47 hospitals were randomly selected by cluster stratified random sampling method. Blood samples were collected from 192 medical staff in intensive care department who had received inactivated novel coronavirus vaccine in 7 hospitals. The antibody concentration was determined by chemiluminescence method to find the antibody rule. Logistic regression analysis was used to determine the related factors affecting the production of antibodies. ResultsTotal antibody concentration of 192 blood samples was 23.25 (5.09, 270.22), IgG concentration was 0.94 (0.15, 4.48), IgM concentration was 0.05 (0.03, 0.12). Logistic regression analysis showed that the total antibody concentration might be related to gender and age, and the IgG concentration was significantly related to whether the third injection was administered. One hundred and twenty-seven people received 2 doses of inactivated vaccine, and the positive rate of IgG was the highest within 1 to 2 months, and decreased significantly after 3 months. The positive rate of IgG antibody was 95.4% within 60 days after receiving 3 doses of vaccine, 70% within 1 month after receiving the third dose of vaccine, and 100.0% within 1 to 2 months (P<0.05). The total antibody positive rate was 96.3% in people aged 17 to 35 years and 73.3% in people aged 36 to 58 years, showing statistical difference (P<0.05). The total antibody production rate of those who received the third dose of vaccine was 100.0%, and no severe case of COVID-19 occurred during the sampling period. Conclusions After the first, second, and third doses of COVID-19 vaccine, the total antibody concentration of the virus gradually increases to 100.0%, indicating initial immunity. However, the antibody concentration decreased gradually after 3 months of inoculation. The concentration of IgG in women is higher than that in men, and the concentration of antibody in young people is higher than that in middle-aged and elderly people during the same period.