J Korean Med Sci.  2021 Mar;36(9):e64. 10.3346/jkms.2021.36.e64.

Comparison of Serologic Response of Hospitalized COVID-19 Patients Using 8 Immunoassays

• Lee SM
• Kim IS
• Lim S
• Lee SJ
• Kim WJ
• Shin KH
• Moon SY
• Chang CL

• KMID: 2513585
• DOI: http://doi.org/10.3346/jkms.2021.36.e64

Abstract

Background
In Korea, there were issues regarding the use of immunoassays for anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies to detect infection. So, we compared antibody results of eight kinds of commercial immunoassays using clinical remnant specimens.
Methods
We compared the results of several immunoassay kits tested on 40 serum samples from 15 confirmed patients and 86 remnant serum samples from clinical laboratory. Eight kinds of IVD kits—four enzyme-linked immunosorbent assay, two lateral flow rapid immunochromatographic assays, and two chemiluminescent immunoassays with one RUO kit were tested.
Results
Among 40 serum samples from 15 coronavirus disease 2019 (COVID-19) patients, 35 yielded at least one positive result for detecting antibodies in the combined assessment. There were inconsistent results in 12 (28%) samples by single immunoassay. Forty samples collected in 2019 before the first COVID-19 Korean case showed negative results except for one equivocal result.
Conclusion
The discrepant results obtained with different immunoassay kits in this study show that serological assessment of SARS-CoV-2 by a single immunoassay requires caution not only in detecting infection but also in assessing immunologic status.

Keyword

SARS-CoV-2; COVID-19; ELISA; Immunoassay; Korea; Antibodies

Figure

• 

  Fig. 1 Serologic response by reaction values of six immunoassays for anti-SARS-CoV-2 antibody. (A) Euroimmun NCP, (B) S1 IgG EIA, (C) PCL total Ab EIA, (D) SD biosensor standard E total Ab, (E) Ortho VITROS IgG, and (F) Ortho VITROS totala—by duration after symptom onsetb.SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2, NCP = nucleocapsid protein, S1 = spike, IgG= immunoglobulin G, Ab = antibody, OD = optical density.aCutoff value (1.0) not displayed due to overlapping of data; bDate after confirmation test for two asymptomatic patients (4 and 11).

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