Assessment of SARS-CoV-2 serological tests for the diagnosis of COVID-19 through the evaluation of three immunoassays: Two automated immunoassays (Euroimmun and Abbott) and one rapid lateral flow immunoassay (NG Biotech)

J Clin Virol. 2020 Aug;129:104511. doi: 10.1016/j.jcv.2020.104511. Epub 2020 Jun 15.


Background: The emergence of new SARS-CoV-2 has promoted the development of new serological tests that could be complementary to RT-PCR. Nevertheless, the assessment of clinical performances of available tests is urgently required as their use has just been initiated for diagnose.

Objectives: The aim of this study was to assess the performance of three immunoassays for the detection of SARS-CoV-2 antibodies.

Methods: Two automated immunoassays (Abbott SARS-CoV-2 CLIA IgG and Euroimmun Anti-SARS-CoV-2 ELISA IgG/IgA assays) and one lateral flow immunoassay (LFIA NG-Test® IgG-IgM COVID-19) were tested. 293 specimens were analyzed from patients with a positive RT-PCR response, from patients with symptoms consistent with COVID-19 but exhibiting a negative response to the RT-PCR detection test, and from control group specimens. Days since symptoms onset were collected from clinical information sheet associated with respiratory tract samples.

Results: Overall sensitivity for IgG was equivalent (around 80 %) for CLIA, ELISA and LFIA. Sensitivity for IgG detection, >14 days after onset of symptoms, was 100.0 % for all assays. Overall specificity for IgG was greater for CLIA and LFIA (more than 98 %) compared to ELISA (95.8 %). Specificity was significantly different between IgA ELISA (78.9 %) and IgM LFIA (95.8 %) (p < 0.05). The best agreement was observed between CLIA and LFIA assays (97 %; k = 0.936).

Conclusion: Excellent sensitivity for IgG detection was obtained >14 days after onset of symptoms for all immunoassays. Specificity was also excellent for IgG CLIA and IgG LFIA. Our study shows that NG-Test® is reliable and accurate for routine use in clinical laboratories.

Keywords: Automated immunoassays; COVID-19; Lateral flow immunoassay; Performance; SARS-CoV-2.

Publication types

  • Comparative Study
  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Antibodies, Viral / blood*
  • Automation, Laboratory / methods
  • Betacoronavirus / immunology*
  • COVID-19
  • COVID-19 Testing
  • Clinical Laboratory Techniques / methods*
  • Coronavirus Infections / diagnosis*
  • Female
  • Humans
  • Immunoassay / methods*
  • Immunoglobulin A / blood
  • Immunoglobulin G / blood
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / diagnosis*
  • Retrospective Studies
  • SARS-CoV-2
  • Sensitivity and Specificity
  • Serologic Tests / methods*
  • Time Factors


  • Antibodies, Viral
  • Immunoglobulin A
  • Immunoglobulin G