Analytical and clinical validation of an ELISA for specific SARS-CoV-2 IgG, IgA and IgM antibodies

Marie Tré-Hardy, Alain Wilmet, Ingrid Beukinga, Julien Favresse, Jean-Michel Dogné, Jonathan Douxfils, Laurent Blairon

Research output: Contribution to journalArticlepeer-review

55 Downloads (Pure)


The development of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serological tests is massive. The external validation of their performance is needed before use in clinical routine practice. Our study aims at assessing the analytical and clinical performance of two enzyme-linked immunosorbent assay tests detecting antibodies directed against the virus nucleocapsid protein: The NovaLisa SARS-CoV-2 immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM) test (NovaTec) allowing a separate detection of each antibody and the Platelia SARS-CoV-2 Total Ab test (Bio-Rad) detecting total antibodies (IgM, IgA, and IgG). Two-hundred and eight coronavirus disease 2019 samples from 48 quantitative reverse transcription-polymerase chain reaction (RT-qPCR) confirmed patients were used to perform the sensitivity analysis. Non-SARS-CoV-2 sera (n = 79) with a potential cross-reaction to SARS-CoV-2 immunoassays were included in the specificity analysis. In addition, using receiver operator characteristic curves, adapted cut-off for improvement of the performances were proposed. The kinetics of these antibodies was also assessed over 8 weeks. Two weeks after the RT-qPCR positive detection, the NovaLisa test shows a sensitivity and specificity of 94.9% (95% confidence interval [CI]: 83.1%-98.6%) and 96.2% (95% CI: 89.4%-98.7%) for IgG, of 89.7% (95% CI: 76.4%-95.9%) and 98.7% (95% CI: 93.2%-98.8%) for IgA, and of 48.7% (95% CI: 33.9%-63.8%) and 98.7% (95% CI: 93.2%-99.8%) for IgM. With the Platelia system, the specificity and sensitivity were 97.4% (95% CI: 92.1%-99.7%) and 94.9% (95% CI: 87.7%-98.0%) for total antibodies using the adapted cut-offs. The NovaLisa and the Platelia tests have satisfactory analytical performances. The clinical performances are excellent for IgG, IgA, and total antibodies especially if the cut-off is optimized.

Original languageEnglish
Pages (from-to)803-811
Number of pages9
JournalJournal of medical virology
Issue number2
Early online date15 Jul 2020
Publication statusPublished - Feb 2021


  • IgA
  • IgG
  • IgM
  • SARS-CoV-2
  • antibodies
  • kinetics
  • Immunoglobulin G/blood
  • Humans
  • Middle Aged
  • Male
  • COVID-19/diagnosis
  • Sensitivity and Specificity
  • Aged, 80 and over
  • Adult
  • Female
  • Retrospective Studies
  • Enzyme-Linked Immunosorbent Assay/standards
  • Antibodies, Viral/blood
  • Immunoglobulin A/blood
  • Severity of Illness Index
  • Immunoglobulin M/blood
  • Intensive Care Units
  • Reverse Transcriptase Polymerase Chain Reaction
  • SARS-CoV-2/immunology
  • Survival Analysis
  • Aged


Dive into the research topics of 'Analytical and clinical validation of an ELISA for specific SARS-CoV-2 IgG, IgA and IgM antibodies'. Together they form a unique fingerprint.

Cite this