Dried blood spot specimens for SARS-CoV-2 antibody testing: A multi-site, multi-assay comparison

PLoS One. 2021 Dec 7;16(12):e0261003. doi: 10.1371/journal.pone.0261003. eCollection 2021.


The true severity of infection due to COVID-19 is under-represented because it is based on only those who are tested. Although nucleic acid amplifications tests (NAAT) are the gold standard for COVID-19 diagnostic testing, serological assays provide better population-level SARS-CoV-2 prevalence estimates. Implementing large sero-surveys present several logistical challenges within Canada due its unique geography including rural and remote communities. Dried blood spot (DBS) sampling is a practical solution but comparative performance data on SARS-CoV-2 serological tests using DBS is currently lacking. Here we present test performance data from a well-characterized SARS-CoV-2 DBS panel sent to laboratories across Canada representing 10 commercial and 2 in-house developed tests for SARS-CoV-2 antibodies. Three commercial assays identified all positive and negative DBS correctly corresponding to a sensitivity, specificity, positive predictive value, and negative predictive value of 100% (95% CI = 72.2, 100). Two in-house assays also performed equally well. In contrast, several commercial assays could not achieve a sensitivity greater than 40% or a negative predictive value greater than 60%. Our findings represent the foundation for future validation studies on DBS specimens that will play a central role in strengthening Canada's public health policy in response to COVID-19.

Publication types

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

MeSH terms

  • Antibodies, Viral / blood*
  • Area Under Curve
  • COVID-19 / diagnosis*
  • COVID-19 / virology
  • COVID-19 Testing / methods*
  • Dried Blood Spot Testing*
  • Humans
  • ROC Curve
  • Reagent Kits, Diagnostic
  • SARS-CoV-2 / isolation & purification
  • Sensitivity and Specificity


  • Antibodies, Viral
  • Reagent Kits, Diagnostic

Grants and funding

Marc-André Langlois (M.-A.L.) holds a Canada Research Chair in Molecular Virology and Intrinsic Immunity. This study was supported in part by a COVID-19 Rapid Response grant to M.-A.L. by the Canadian Institute of Health Research (CIHR; OV1-170355) and by a grant supplement by the COVID-19 Immunity Task Force (CITF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. The authors did not receive a salary from any of the funders.