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. 2021 Feb 18:8:620222.
doi: 10.3389/fpubh.2020.620222. eCollection 2020.

Recent Advances in the Evaluation of Serological Assays for the Diagnosis of SARS-CoV-2 Infection and COVID-19

Angela Chiereghin  1 , Rocco Maurizio Zagari  2 , Silvia Galli  3 , Alessandra Moroni  3 , Liliana Gabrielli  3 , Simona Venturoli  3 , Isabella Bon  3 , Giada Rossini  3 , Ilaria Maria Saracino  1 , Matteo Pavoni  1 , Silvia Lafratta  1 , Alessandro Deni  1 , Silvia Felici  1 , Michele Borghi  1 , Luca Guerra  4 , Luigi Raumer  4 , Vittorio Lodi  5 , Pierluigi Viale  6 , Luciano Attard  6 , Tiziana Lazzarotto  1 ; IRCCS St. Orsola Polyclinic of Bologna COVID-19 Research Team
Affiliations

Recent Advances in the Evaluation of Serological Assays for the Diagnosis of SARS-CoV-2 Infection and COVID-19

Angela Chiereghin et al. Front Public Health. .

Abstract

Introduction: Few data on the diagnostic performance of serological tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are currently available. We evaluated sensitivity and specificity of five different widely used commercial serological assays for the detection of SARS-CoV-2-specific IgG, IgM, and IgA antibodies using reverse transcriptase-PCR assay in nasopharyngeal swab as reference standard test. Methods: A total of 337 plasma samples collected in the period April-June 2020 from SARS-CoV-2 RT-PCR positive (n = 207) and negative (n = 130) subjects were investigated by one point-of-care lateral flow immunochromatographic assay (LFIA IgG and IgM, Technogenetics) and four fully automated assays: two chemiluminescence immunoassays (CLIA-iFlash IgG and IgM, Shenzhen YHLO Biotech and CLIA-LIAISON® XL IgG, DiaSorin), one electrochemiluminescence immunoassay (ECLIA-Elecsys® total predominant IgG, Roche), and one enzyme-linked immunosorbent assay (ELISA IgA, Euroimmune). Results: The overall sensitivity of all IgG serological assays was >80% and the specificity was >97%. The sensitivity of IgG assays was lower within 2 weeks from the onset of symptoms ranging from 70.8 to 80%. The LFIA and CLIA-iFlash IgM showed an overall low sensitivity of 47.6 and 54.6%, while the specificity was 98.5 and 96.2%, respectively. The ELISA IgA yielded a sensitivity of 84.3% and specificity of 81.7%. However, the ELISA IgA result was indeterminate in 11.7% of cases. Conclusions: IgG serological assays seem to be a reliable tool for the retrospective diagnosis of SARS-CoV-2 infection. IgM assays seem to have a low sensitivity and IgA assay is limited by a substantial rate of indeterminate results.

Keywords: CLIA; COVID-19; ECLIA and ELISA; LFIA; SARS-CoV-2 RT-PCR; SARS-CoV-2 infection; SARS-CoV-2-specific antibodies; sensitivity and specificity.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Receiver operating characteristic (ROC) curves for the diagnosis of SARS-CoV-2 infection by IgG and IgM LFIA (A) and CLIA-iFlash (B) using RT-PCR as reference standard ROC area IgG vs. IgM LFIA, p < 0.0001; ROC area IgG vs. IgM CLIA-iFlash, p < 0.0001.
See this image and copyright information in PMC

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