Abstract
With the availability of vaccines, commercial assays detecting anti-severe acute respiratory syndrome coronavirus-2 antibodies (Ab) evolved toward quantitative assays directed to the spike glycoprotein or its receptor binding domain (RBD). The main objective of the present study was to compare the Ab titers obtained with quantitative commercial binding Ab assays, after one dose (convalescent individuals) or two doses (naive individuals) of vaccine, in health care workers (HCW). Antibody titers were measured in 255 sera (from 150 HCW) with five quantitative immunoassays (Abbott RBD IgG II quant, bioMérieux RBD IgG, DiaSorin Trimeric spike IgG, Siemens Healthineers RBD IgG, Wantai RBD IgG). One qualitative total antibody anti-RBD detection assay (Wantai) was used to detect previous infection before vaccination. The results are presented in binding Ab units (BAU)/mL after application, when possible, of a conversion factor provided by the manufacturers and established from a World Health Organization internal standard. There was a 100% seroconversion with all assays evaluated after two doses of vaccine. With assays allowing BAU/mL correction, Ab titers were correlated (Pearson correlation coefficient, ρ, range: 0.85-0.94). The titer differences varied by a mean of 10.6% between Siemens and bioMérieux assays to 60.9% between Abbott and DiaSorin assays. These results underline the importance of BAU conversion for the comparison of Ab titer obtained with the different quantitative assays. However, significant differences persist, notably, between kits detecting Ab against the different antigens. A true standardization of the assays would be to include the International Standard in the calibration of each assay to express the results in IU/mL.
Keywords: SARS-CoV-2 antibodies; commercial assays; health care workers; immunization; quantification; standardized titers; vaccination.
【저자키워드】 vaccination, health care workers, immunization, SARS-CoV-2 antibodies, quantification, commercial assays, standardized titers, 【초록키워드】 SARS-CoV-2, Vaccine, vaccination, Health care, Vaccines, antibody, health care workers, spike glycoprotein, Infection, immunization, Receptor binding domain, immunoassay, Health, Seroconversion, SARS-CoV-2 antibodies, RBD, BAU, titer, sera, Health care worker, antigens, respiratory, Quantitative, Care, Antibody titers, spike IgG, binding, international standard, Coronavirus-2, dose, Quantitative assays, bioMérieux, Standard, Standardization, anti-RBD, Abbott, HCW, Health Organization, World Health Organization, acute respiratory syndrome, conversion factor, significant difference, significant differences, naïve individuals, calibration, DiaSorin, RBD IgG, Express, convalescent individuals, quantitative assay, Siemens, Pearson correlation coefficient, FIVE, was used, detect, include, assays, evaluated, provided, correlated, individuals, were measured, Siemen, Siemens Healthineer, 【제목키워드】 worker,