Performance of SARS-CoV-2 serology tests: Are they good enough?

PLoS One. 2021 Feb 17;16(2):e0245914. doi: 10.1371/journal.pone.0245914. eCollection 2021.

Abstract

In the emergency of the SARS-CoV-2 pandemic, great efforts were made to quickly provide serology testing to the medical community however, these methods have been introduced into clinical practice without the complete validation usually required by the regulatory organizations. SARS-CoV-2 patient samples (n = 43) were analyzed alongside pre-pandemic control specimen (n = 50), confirmed respiratory infections (n = 50), inflammatory polyarthritis (n = 22) and positive for thyroid stimulating immunoglobulin (n = 30). Imprecision, diagnostic sensitivity and specificity and concordance were evaluated on IgG serologic assays from EuroImmun, Epitope Diagnostics (EDI), Abbott Diagnostics and DiaSorin and a rapid IgG/IgM test from Healgen. EDI and EuroImmun imprecision was 0.02-14.0% CV. Abbott and DiaSorin imprecision (CV) ranged from 5.2%-8.1% and 8.2%-9.6% respectively. Diagnostic sensitivity of the assays was 100% (CI: 80-100%) for Abbott, EDI and EuroImmun and 95% (CI: 73-100%) for DiaSorin at ≥14 days post PCR. Only the Abbott assay had a diagnostic specificity of 100% (CI: 91-100%). EuroImmun cross-reacted in 3 non-SARS-CoV-2 respiratory infections and 2 controls. The DiaSorin displayed more false negative results and cross-reacted in six cases across all conditions tested. EDI had one cross-reactive sample. The Healgen rapid test showed excellent sensitivity and specificity. Overall, concordance of the assays ranged from 76.1% to 97.9%. Serological tests for SARS-CoV-2 showed good analytical performance. The head-to-head analysis of samples revealed differences in results that may be linked to the use of nucleocapsid or spike proteins. The point of care device tested demonstrated adequate performance for antibody detection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Viral / blood
  • Brazil / epidemiology
  • COVID-19 / diagnosis*
  • COVID-19 / epidemiology
  • COVID-19 / immunology
  • COVID-19 / virology
  • COVID-19 Serological Testing / methods*
  • COVID-19 Serological Testing / trends
  • Clinical Laboratory Techniques / methods
  • Cross Reactions
  • Humans
  • Immunoglobulin G / blood
  • Immunoglobulin M / blood
  • Pandemics
  • Point-of-Care Systems
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / isolation & purification
  • Sensitivity and Specificity

Substances

  • Antibodies, Viral
  • Immunoglobulin G
  • Immunoglobulin M

Grants and funding

The authors received no specific financial support for this study. They acknowledge the Norfolk, Suffolk, Essex and Bedfordshire Freemasons for their generous material support in providing funding for some equipment used in this study.