Assessment of S-Specific IgG and IgM Positive Rates in Healthy Hospital Staff Members Vaccinated with the Inactivated SARS-CoV-2 Vaccine

Widespread vaccination of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine makes the assessment of antibodies' positive rates essential. In this study, a total of 378 hospital staff members vaccinated with the vaccine were selected as research subjects. Serum-specific IgG and IgM against the SARS-CoV-2 spike protein (S) were detected, and S-specific IgG and IgM positive rates were analyzed in different age and sex groups, as was the serological pattern of IgG/IgM. The positive rates of IgG and IgM were 92.06% and 44.44%, respectively. The percentage of both IgG and IgM positive (IgG(+)IgM(+)) was 43.92%. A total of 182 vaccinees (46.90%) were IgG positive and IgM negative (IgG(+)IgM(-)), and 28 vaccinees (7.41%) were negative for both IgG and IgM (IgG(-)IgM(-)); 2 participants were positive for IgM alone (IgG(-)IgM(+)). In sex subgroups, the rate of IgM positivity was significantly higher in the male group than in the female group (p = 0.027). In different age subgroups, positive rates for IgG in the young group were significantly higher than those in the other group (p = 0.035). Furthermore, ratios of sample values to cutoff values (S/CO values) for IgG in vaccinees who were S-specific IgG positive were compared, and the S/CO values of IgG were significantly higher in the younger group than in the other group (p < 0.001). When comparing the influence of sex on two specific serological patterns (IgG(+)IgM(-) and IgG(+)IgM(+)), a significant difference in positivity rates was detected (p = 0.011). Male vaccinees were more likely than females to have an IgG(+)IgM(+) pattern.