Diagnostic accuracy of two commercial SARS-CoV-2 antigen-detecting rapid tests at the point of care in community-based testing centers

PLoS One. 2021 Mar 31;16(3):e0248921. doi: 10.1371/journal.pone.0248921. eCollection 2021.

Abstract

Objectives: Determine the diagnostic accuracy of two antigen-detecting rapid diagnostic tests (Ag-RDT) for SARS-CoV-2 at the point of care and define individuals' characteristics providing best performance.

Methods: We performed a prospective, single-center, point of care validation of two Ag-RDT in comparison to RT-PCR on nasopharyngeal swabs.

Results: Between October 9th and 23rd, 2020, 1064 participants were enrolled. The PanbioTM Covid-19 Ag Rapid Test device (Abbott) was validated in 535 participants, with 106 positive Ag-RDT results out of 124 positive RT-PCR individuals, yielding a sensitivity of 85.5% (95% CI: 78.0-91.2). Specificity was 100.0% (95% CI: 99.1-100) in 411 RT-PCR negative individuals. The Standard Q Ag-RDT (SD Biosensor, Roche) was validated in 529 participants, with 170 positive Ag-RDT results out of 191 positive RT-PCR individuals, yielding a sensitivity of 89.0% (95%CI: 83.7-93.1). One false positive result was obtained in 338 RT-PCR negative individuals, yielding a specificity of 99.7% (95%CI: 98.4-100). For individuals presenting with fever 1-5 days post symptom onset, combined Ag-RDT sensitivity was above 95%. Lower sensitivity of 88.2% was seen on the same day of symptom development (day 0).

Conclusions: We provide an independent validation of two widely available commercial Ag-RDTs, both meeting WHO criteria of ≥80% sensitivity and ≥97% specificity. Although less sensitive than RT-PCR, these assays could be beneficial due to their rapid results, ease of use, and independence from existing laboratory structures. Testing criteria focusing on patients with typical symptoms in their early symptomatic period onset could further increase diagnostic value.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antigens, Viral / analysis*
  • COVID-19 Testing*
  • Female
  • Humans
  • Male
  • Point-of-Care Systems*
  • Residence Characteristics*
  • SARS-CoV-2 / immunology*
  • SARS-CoV-2 / isolation & purification*
  • SARS-CoV-2 / physiology
  • Sensitivity and Specificity
  • Time Factors
  • Viral Load

Substances

  • Antigens, Viral

Grant support

The study was supported by the Foundation for Innovative New Diagnostics (https://www.finddx.org/), the Fondation privée des HUG (https://www.fondationhug.org/) and Pictet Charitable Foundation (https://www.group.pictet/responsible-vision/pictet-group-foundation). M.T. Ngo Nsoga is a beneficiary of the excellence grant from the Swiss confederation (https://www.sbfi.admin.ch/sbfi/en/home/education/scholarships-and-grants/swiss-government-excellence-scholarships.html) and the grant from the humanitarian commission of the university hospitals of Geneva (https://www.hug.ch/en/external-affairs-directorate). The Foundation for Innovative New Diagnostics provided rapid tests and elements of the study protocol. The funders had no other roles in study design, data collection and analysis, decision to publish, or preparation of the manuscript.