Evaluation of serological assays for SARS-CoV-2 antibody testing from dried blood spots collected from cohorts with prior SARS-CoV-2 infection

Beth Catlett; Mitchell Starr; Dorothy A Machalek; Thidarat Danwilai; Michael Palmer; Andrew Kelly; John Kaldor; Gregory J Dore; David Darley; Gail Matthews; Philip H Cunningham

doi:10.1016/j.jcvp.2022.100093

Evaluation of serological assays for SARS-CoV-2 antibody testing from dried blood spots collected from cohorts with prior SARS-CoV-2 infection

J Clin Virol Plus. 2022 Aug;2(3):100093. doi: 10.1016/j.jcvp.2022.100093. Epub 2022 Jun 24.

Authors

Beth Catlett^{1

2

3}, Mitchell Starr^{1

3}, Dorothy A Machalek^{2

4}, Thidarat Danwilai^{1

3}, Michael Palmer^{1

3}, Andrew Kelly^{1

3}, John Kaldor², Gregory J Dore^{2

3}, David Darley^{3

5

6}, Gail Matthews^{2

3}, Philip H Cunningham^{1

2

3}

Affiliations

¹ NSW State Reference Laboratory for HIV, St Vincent's Centre for Applied Medical Research, Darlinghurst, Sydney, New South Wales, Australia.
² The Kirby Institute, UNSW Sydney, Sydney, New South Wales, Australia.
³ St Vincent's Hospital, Sydney, New South Wales, Australia.
⁴ Centre for Women's Infectious Diseases, The Royal Women's Hospital, Melbourne, Australia.
⁵ Department of Thoracic Medicine, St Vincent's Hospital, Sydney, New South Wales, Australia.
⁶ UNSW Medicine, St Vincent's Clinical School, University of New South Wales, Australia.

Abstract

Background: Dried blood spot (DBS) specimens are a useful serosurveillance tool particularly in hard-to-reach populations but their application for detecting SARS-CoV-2 infection is poorly characterised.

Objectives: To compare detection of naturally acquired SARS-CoV-2 antibodies in paired DBS and serum specimens using commercially available serological immunoassays.

Study design: Specimens were collected through St Vincent's Hospital observational post COVID-19 cohort study (ADAPT). Laboratory spotted DBS from venepuncture were initially tested on seven assays, a DBS validation completed on three with clinically collected fingerstick DBSs tested on one.

Results: Sensitivity for Euroimmun nucleocapsid (NCP) IgG ELISA from laboratory spotted DBS (n=145), Euroimmun spike, IgG ELISA from laboratory spotted DBS (n=161), and Binding Site total antibody ELISA from clinically collected fingerstick DBS (n=391) was 100% (95% CI: 95.8-100%), 100% (95% CI: 95.8-100%) and 92.9% (95% CI: 89.5-95.5%), respectively. Specificity was 66.2% (95% CI: 53.6-77.0%), 96% (95% CI: 88.7-99.1%) and 98.8% (95% CI: 93.3-99.9%), respectively. All three assays' results displayed a strong positive correlation between DBS compared to paired serum.

Conclusions: The Binding Site™ spike total antibody and Euroimmun™ spike IgG ELISAs provided good analytical performance, demonstrating that DBS specimens could facilitate specimen collection in the epidemiological surveillance of SARS-CoV-2 infection. This is highly applicable in populations and settings where venepuncture is problematic (including community based regional/remote settings, nursing homes, prisons, and schools).

Keywords: COVID-19; DBS; Diagnostics; Dried blood spots; SARS-CoV-2; Surveillance.