Diagnostic performance of seven rapid IgG/IgM antibody tests and the Euroimmun IgA/IgG ELISA in COVID-19 patients

Clin Microbiol Infect. 2020 Aug;26(8):1082-1087. doi: 10.1016/j.cmi.2020.05.023. Epub 2020 May 28.


Objectives: To evaluate the diagnostic performance of seven rapid IgG/IgM tests and the Euroimmun IgA/IgG ELISA for antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in COVID-19 patients.

Methods: Specificity was evaluated in 103 samples collected before January 2020. Sensitivity and time to seropositivity was evaluated in 167 samples from 94 patients with COVID-19 confirmed with RT-PCR on nasopharyngeal swab.

Results: Specificity (confidence interval) of lateral flow assays (LFAs) was ≥91.3% (84.0-95.5) for IgM, ≥90.3% (82.9-94.8) for IgG, and ≥85.4% (77.2-91.1) for the combination IgM OR IgG. Specificity of the ELISA was 96.1% (90.1-98.8) for IgG and only 73.8% (64.5-81.4) for IgA. Sensitivity 14-25 days after the onset of symptoms was between ≥92.1% (78.5-98.0) and 100% (95.7-100) for IgG LFA compared to 89.5% (75.3-96.4) for IgG ELISA. Positivity of IgM OR IgG for LFA resulted in a decrease in specificity compared to IgG alone without a gain in diagnostic performance, except for VivaDiag. The results for IgM varied significantly between the LFAs with an average overall agreement of only 70% compared to 89% for IgG. The average dynamic trend to seropositivity for IgM was not shorter than for IgG. At the time of hospital admission the sensitivity of LFA was <60%.

Conclusions: Sensitivity for the detection of IgG antibodies 14-25 days after the onset of symptoms was ≥92.1% for all seven LFAs compared to 89.5% for the IgG ELISA. The results for IgM varied significantly, and including IgM antibodies in addition to IgG for the interpretation of LFAs did not improve the diagnostic performance.

Keywords: COVID-19; Diagnosis; ELISA; Immunoassay; Lateral flow assay; Point-of-care testing; SARS-CoV-2; Sensitivity and specificity; Seroconversion.

Publication types

  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Antibodies, Viral / analysis*
  • Antigens, Viral / immunology*
  • Betacoronavirus / immunology*
  • COVID-19
  • Coronavirus Infections / diagnosis*
  • Coronavirus Infections / immunology
  • Diagnostic Tests, Routine
  • Female
  • Humans
  • Immunoglobulin A / metabolism
  • Immunoglobulin G / metabolism
  • Immunoglobulin M / metabolism
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / diagnosis*
  • Pneumonia, Viral / immunology
  • SARS-CoV-2
  • Sensitivity and Specificity
  • Time Factors
  • Young Adult


  • Antibodies, Viral
  • Antigens, Viral
  • Immunoglobulin A
  • Immunoglobulin G
  • Immunoglobulin M