| Objective:1.The performance of two SARS-Cov-2 neutralizing antibody detection kits was validated using a magnetic particle chemiluminescence immunoassay.2.A complete population of second and third doses of inactivated SARS-Cov-2 vaccine was tested for serum IgM,IgG antibody and neutralizing antibody to assess the antibody production level and antibody positive rate of the vaccine after vaccination.3.The objective of this study was to investigate whether there was a significant correlation between serum IgM,IgG antibody and neutralizing antibody levels after inactivated SARS-Cov-2 vaccine in populations of different gender,age and BMI.Methods:1.A population of people(n=187)vaccinated with inactivated SARS-Cov-2vaccine in Chengdu,Sichuan Province from January to February 2021 was collected.Reference was made to the series of documents issued by CLSI and CNAS as well as the requirements of national health industry standards.The performance of the SARS-Cov-2 neutralizing antibody test kits for maccura i3000 and Auto Lumo A2000 Plus was validated for precision,accuracy,linear range,detection limit and reference interval to verify that their performance met the requirements of the manufacturer’s instructions.2.The population(n=375)vaccinated with inactivated SARS-Cov-2vaccine in Chengdu,Sichuan Province from January to December 2021 was collected.Grouped according to different doses and duration of vaccination.The second 28-day vaccination group(S2D28)was formed 28 days after second doses of inactivated SARS-Cov-2 vaccine(n=194).The second 180-day dose group(S2D180),was formed 180 days after second doses of inactivated SARS-Cov-2 vaccine(n=68).The third 28-day vaccination group(S3D28)was formed 28 days after third doses of inactivated SARS-Cov-2 vaccine(n=65).The third 150-day vaccination group(S3D150)was formed 150 days after third doses of inactivated SARS-Cov-2 vaccine(n=48).The serum IgM,IgG antibody and neutralizing antibody levels were quantified using a maccura i3000chemiluminescent analyser.Results:1.Results of performance evaluation of two kinds of kitThe maccura i3000 kind of kit met the requirements for precision,accuracy and reference interval with a linear range of 7.266 to 91.695AU/m L.Accuracy,precision and minimum detection line of the Auto Lumo A2000 Plus kind of kit were achieved with a linear range of 72.77 to 2615.83AU/m L.Both maccura i3000 kind of kit and Auto Lumo A2000Plus kind of kit are correlated in the detection of SARS-Cov-2 neutralizing antibody,and both can detect serum neutralizing antibody in post-vaccination population.2.Study of antibody levels in inactivated SARS-Cov-2 vaccine recipientsA total of 375 study cases were included,122 males and 253 females,aged23 to 65 years,with a mean age of 38.18 years.The positive IgM antibody rates for S2D28,S2D180,S3D28 and S3D150 were 17.0%,2.9%,6.2%and 2.1%respectively.There was a statistically significant overall difference in the comparison of IgM antibody positive rates(P<0.001).IgM antibody levels were 0.21(0.08,0.63),0.06(0.04,0.10),0.07(0.04,0.13)and 0.04(0.03,0.06),respectively.There was a statistically significant overall difference in the comparison of IgM antibody levels(P<0.001).The positive IgG antibody rates for S2D28,S2D180,S3D28 and S3D150were 76.3%,18.8%,90.8%and 70.8%,respectively.There was a statistically significant overall difference in the comparison of IgG antibody positive rates(P<0.001).The levels of IgG antibodies were 2.58(1.02,4.76),0.34(0.07,0.80),4.56(3.40,7.15)and 1.72(0.81,3.24)respectively.There was a statistically significant overall difference in the comparison of IgG antibody levels(P<0.001).The positive neutralizing antibody antibody rates for 71.1%,26.1%,100%and 100%for S2D28,S2D180,S3D28 and S3D150 respectively.There was a statistically significant overall difference in the comparison of neutralizing antibody positive rates(P<0.001).Neutralizing antibody levels were 10.20(5.43,26.34),4.18(3.00,6.54),36.92(22.44,101.60)and 33.89(20.29,70.51)respectively.The overall difference was statistically significant in the comparison of neutralizing antibody levels(P<0.001).IgM antibody for S2D28,IgG antibody for S2D180 and S3D28,and neutralizing antibody for S3D28 all had significantly higher antibody levels in men than in women(P<0.05).The IgG antibody to S2D28 and the neutralizing antibody to S2D180 were significantly higher in the young and middle-aged population(<45 years)than in the middle-aged and older population(≥45 years)(P<0.05).Antibody levels of IgG antibody and neutralizing antibody to S2D28were significantly higher in the normal weight population(<23 kg/m~2)than in the overweight and obese population(≥23 kg/m~2)(P<0.05).Conclusion:1.All performance validations of the SARS-Cov-2 neutralizing antibody assay kits provided by Maccura Biotechnology and Auto Lumo Diagnostics passed and were able to achieve the performance claimed in the manufacturer’s instructions.Both of them have some correlation in the detection of neutralizing antibody levels,and both can detect serum neutralizing antibody levels in the post-vaccination population.2.All healthy people vaccinated with the inactivated SARS-Cov-2 vaccine can produce IgM and IgG antibody and neutralizing antibody.The levels of IgM,IgG antibody and neutralizing antibody decreased after 180 days of the second dose of vaccine.High levels of IgG antibody and neutralizing antibody remained after 150 days of the third dose of vaccine.3.Significantly higher levels of IgG antibody and neutralizing antibody and higher levels of immune protection were induced after the third dose of inactivated SARS-Cov-2 vaccine compared to second doses of inactivated SARS-Cov-2 vaccine.4.Gender,age and BMI had an impact on the production of IgM,IgG and neutralizing antibody levels,with males,young people and those of normal weight producing higher levels of antibody.However,we still need further studies to determine whether it is their common factors or different factors that lead to these associations. |
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