There is no significant difference in IgG levels between male and female groups, which reach the peak in the second week and then gradually decreases without a significant difference about the magnitude of the decrease. for titre of IgM during the prior 2 weeks and among three age groups for titre of IgG during the 2ndC3rd week after vaccination. The GMT level of IgG in the population vaccinated with the COVID-19 vaccine remained at a high level within 25 weeks and peaked on the 13th day, indicating that IgG could exist for a longer period and exhibiting positive SARS-CoV-2- defending effect. (%)((test, and the threshold of significance was 0.05. The factors for false-positive results were analysed with a multiple Logistic regression model. The difference was statistically significant at value less than 0.05. Results Characteristics of subjects Among the 1218 antibody-positive samples, 59 (data excluded) cases were not vaccinated with the COVID-19 vaccine, and 66 (data excluded) were not vaccinated with complete doses of the COVID-19 vaccine. The age of 1093 people who were vaccinated with complete doses of COVID-19 vaccine ranged from 18 to 86 years old, with a median of 51 years old. There were 1062 samples from people who were vaccinated with inactivated Vero cells based vaccines, 24 inactivated CHO cells based vaccines and 7 adenovial-vector-based vaccines. The other characteristics of the subjects are shown in Table 1. Dynamic changes of antibody titre GMT (S/CO) of IgM from people who were administrated with complete doses of COVID-19 vaccine reached at peak value at the second week, and then the IgM level gradually decreased over time, turning negative (GMT? ?1 S/CO) at the third week (1.001C1.028) maybe a factor causing the false-positive result of the SARS-Cov-2 IgG antibody ( em P /em ?=?0.035), as shown in Table 5. Table 5. Analyses of factors about false positive result thead th align=”left” rowspan=”2″ colspan=”1″ Variables /th th align=”center” rowspan=”2″ colspan=”1″ False positive group /th th align=”center” rowspan=”2″ colspan=”1″ Control group /th th align=”center” colspan=”2″ rowspan=”1″ Univariate analyse /th th align=”center” colspan=”2″ rowspan=”1″ Multivariate analyses /th th align=”left” colspan=”1″ rowspan=”1″ em X /em 2/ em t /em /th th align=”center” colspan=”1″ rowspan=”1″ em P /em /th th align=”center” colspan=”1″ rowspan=”1″ OR ( em 95%CI /em ) /th th align=”center” colspan=”1″ rowspan=”1″ em P /em /th /thead GenderMale (36, 61.017%)Male (75, 55.970%)0.1450.704CCAge47.356??17.19150.164??25.1270.9030.368CCHepatitis B surface antibody (HBsAb)6.560 (3.460, 95.540)7.190 (2.570, 75.623)1.0260.309CCHepatitis B e antibody (HBeAb)1.410 (1.245, 4.455)1.260 (1.150, 1.478)2.890.0051.015 (1.001,1.028)0.035Hepatitis B core antibody (HBcAb)10.860 (4.250, 74.065)4.835 (4.245, 11.800)2.7110.0081.004 (0.995,1.013)0.386Thyroid peroxidase antibody (TPOAb)4.300 (2.250, 13.350)4.900 (2.600, 19.900)0.620.538CCThyroglobulin antibody (TGAb)7.035 (5.290, 11.585)7.610 (5.660, 9.625)1.2020.26CCThyrotropin receptor antibody (TRAb)14.650 (10.380, 23.868)11.420 (10.633, 13.380)0.9480.347CCC-reactive protein (CRP)0.800??0.0010.813??0.0820.6340.527CCRheumatoid factor (RF)9.400 (8.350, 11.700)9.800 (8.350, 16.100)0.0670.947CCAnti-streptococcal lysozyme O (ASO)33.000 (15.000, 44.000)14.000 (4.000, 49.000)0.3890.699CC Open in a separate window Discussion Previous studies have revealed that those who could generate the immune response after vaccination (IgM/IgG can be detected in vivo) may still be infected with SARS-Cov-2. Nevertheless, they can rapidly produce a large number of IgG R18 that perform a protective function after infection in comparison to those who had not been vaccinated [7]. The National Health Committee of Mouse monoclonal to OCT4 China R18 had issued the COVID-19 survivors recovery plasma treatment (trial edition) to utilise the plasma of COVID-19 survivors as a therapeutic regimen, which indicates that it exerts important effects for COVID-19 patients with the plasma antibody at a high titre. Generally, the serum antibody level R18 is one of the important indicators to evaluate the risk of epidemic disease, but the protective concentration of COVID-19 antibody is unknown at present. One of the possible reasons that those vaccinated and having antibodies against the COVID-19 vaccine were infected by SARS-Cov-2 is that some IgG are not neutralising antibodies and play a limited R18 protective role [8]. Second, there may be R18 an immune escape reaction because of.