Comprehensive analytical and clinical evaluation of a RNA extraction-free saliva-based molecular assay for SARS-CoV-2

PLoS One. 2022 May 5;17(5):e0268082. doi: 10.1371/journal.pone.0268082. eCollection 2022.

Abstract

Standard SARS-CoV-2 testing protocols using nasopharyngeal/throat (NP/T) swabs are invasive and require trained medical staff for reliable sampling. In addition, it has been shown that PCR is more sensitive as compared to antigen-based tests. Here we describe the analytical and clinical evaluation of our in-house RNA extraction-free saliva-based molecular assay for the detection of SARS-CoV-2. Analytical sensitivity of the test was equal to the sensitivity obtained in other Dutch diagnostic laboratories that process NP/T swabs. In this study, 955 individuals participated and provided NP/T swabs for routine molecular analysis (with RNA extraction) and saliva for comparison. Our RT-qPCR resulted in a sensitivity of 82,86% and a specificity of 98,94% compared to the gold standard. A false-negative ratio of 1,9% was found. The SARS-CoV-2 detection workflow described here enables easy, economical, and reliable saliva processing, useful for repeated testing of individuals.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19 Testing
  • COVID-19* / diagnosis
  • Humans
  • Nasopharynx
  • RNA
  • RNA, Viral / genetics
  • SARS-CoV-2* / genetics
  • Saliva
  • Sensitivity and Specificity
  • Specimen Handling / methods

Substances

  • RNA, Viral
  • RNA

Grants and funding

This research was funded by the Centre of Expertise High Tech Systems and Materials (Fontys University of Applied Sciences) and the Dutch ministry of Education Culture and Science. TM4 buffer was kindly provided by 2Wave Diagnostics. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.