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

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

JOURNAL=Frontiers in Public Health

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/public-health/articles/10.3389/fpubh.2020.620222

DOI=10.3389/fpubh.2020.620222

ISSN=2296-2565

ABSTRACT=<p><bold>Introduction:</bold> 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.</p><p><bold>Methods:</bold> A total of 337 plasma samples collected in the period April–June 2020 from SARS-CoV-2 RT-PCR positive (<italic>n</italic> = 207) and negative (<italic>n</italic> = 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<sup>®</sup> XL IgG, DiaSorin), one electrochemiluminescence immunoassay (ECLIA-Elecsys<sup>®</sup> total predominant IgG, Roche), and one enzyme-linked immunosorbent assay (ELISA IgA, Euroimmune).</p><p><bold>Results:</bold> The overall sensitivity of all IgG serological assays was &gt;80% and the specificity was &gt;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.</p><p><bold>Conclusions:</bold> 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.</p>