Lab Med Qual Assur.  2021 Dec;43(4):199-207. 10.15263/jlmqa.2021.43.4.199.

Clinical Evaluation of Five Commercial Serological SARS-CoV-2 Immunoassays for COVID-19

• Shin W
• Bang HI
• Yu GY
• Kim MY
• Jang EY
• Kim JA
• Kim J
• Park R
• Shin JW
• Choi TY

• KMID: 2524188
• DOI: http://doi.org/10.15263/jlmqa.2021.43.4.199

Abstract

Background
Coronavirus disease 2019 (COVID-19) is a serious infectious disease caused by the highly contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, three types of kits for the lateral flow assay (LFA) and two types of reagents used in the chemiluminescent immunoassay (CLIA) for serological testing of COVID-19 were evaluated and compared to investigate the current status of antibody testing.
Methods
From January 2020 to February 2021, 193 positive and 94 negative samples were tested. For these samples, WonMed COVID-19 immunoglobulin M (IgM)/immunoglobulin G (IgG) (Wonmed, Korea), careUS COVID-19 IgM/IgG (WELLS BIO, Korea), and STANDARD Q COVID-19 IgM/IgG Plus test (SD Biosensors, Korea) kits were used for the LFA, and Anti-SARS-CoV2 Elecsys nucleocapsid (N) and spike (S) (Roche, Switzerland) and ACCESS SARSCoV-2 IgM and IgG (Beckman Coulter, USA) for the CLIA were compared and evaluated.
Results
All kits and reagents except Elecsys showed variable sensitivities of 46.1%–72.0% for IgM, and 85.0%–88.1% for IgG. Elecsys showed a sensitivity of 86.0% for the N antibody and 85.5% for the S antibody. All reagents showed higher sensitivity in samples 14 days after symptom onset than within 14 days (P=0.007). The specificity of LFA and CLIA was 97.9%–100.0%.
Conclusions
Most kits and reagents showed low clinical sensitivity at 7–14 days, that is before the antibody was sufficiently produced. When performing a serological test, IgM and IgG should be checked together to obtain sufficient clinical sensitivity, and the test timing should also be applied carefully.

Keyword

COVID-19; SARS-COV-2; COVID-19 serological testing; Immuno assay; Antibodies