Evaluation of the EDI enzyme linked immunosorbent assays for the detection of SARS-CoV-2 IgM and IgG antibodies in human plasma

Clin Chim Acta. 2020 Oct;509:79-82. doi: 10.1016/j.cca.2020.05.047. Epub 2020 Jun 8.


Background: Besides SARS-CoV-2 RT-PCR testing, serological testing is emerging as additional option in COVID-19 diagnostics. Aim of this study was to evaluate novel immunoassays for detection of SARS-CoV-2 antibodies in human plasma.

Methods: Using EDITM Novel Coronavirus COVID-19 Enzyme Linked Immunosorbent Assays (ELISAs), we measured SARS-CoV-2 IgM and IgG antibodies in 64 SARS-CoV-2 RT-PCR confirmed COVID-19 patients with serial blood samples (n = 104) collected at different time points from symptom onset. Blood samples from 200 healthy blood donors and 256 intensive care unit (ICU) patients collected before the COVID-19 outbreak were also used.

Results: The positivity rates in the COVID-19 patients were 5.9% for IgM and 2.9% for IgG ≤ 5 days after symptom onset; Between day 5 and day 10 the positivity rates were 37.1% for IgM and 37.1% for IgG and rose to 76.4% for IgM and 82.4% for IgG after > 10-15 days. After 15-22 days the "true" positivity rates were 94.4% for IgM and 100% for IgG. The "false" positivity rates were 0.5% for IgM and 1.0% for IgG in the healthy blood donors, 1.6% for IgM and 1.2% for IgG in ICU patients.

Conclusions: This study shows high "true" vs. low "false" positivity rates for the EDITM SARS-CoV-2 IgM and IgG ELISAs.

Keywords: Antibody testing; COVID-19; ELISA; SARS-CoV-2; Serological test.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antibodies, Viral / blood*
  • Betacoronavirus* / isolation & purification
  • COVID-19
  • Coronavirus Infections / blood*
  • Coronavirus Infections / diagnosis
  • Enzyme-Linked Immunosorbent Assay / methods
  • Enzyme-Linked Immunosorbent Assay / standards
  • Female
  • Humans
  • Immunoglobulin G / blood*
  • Immunoglobulin M / blood*
  • Male
  • Middle Aged
  • Pandemics
  • Pneumonia, Viral / blood*
  • Pneumonia, Viral / diagnosis
  • SARS-CoV-2
  • Serologic Tests / methods
  • Serologic Tests / standards*


  • Antibodies, Viral
  • Immunoglobulin G
  • Immunoglobulin M