Sampling site for SARS-CoV-2 RT-PCR-An intrapatient four-site comparison from Tampere, Finland

PLoS One. 2021 Nov 16;16(11):e0260184. doi: 10.1371/journal.pone.0260184. eCollection 2021.

Abstract

Background: SARS-CoV-2 diagnosis relies on the performance of nasopharyngeal swabs. Alternative sample sites have been assessed but the heterogeneity of the studies have made comparing different sites difficult.

Objectives: Our aim was to compare the performance of four different sampling sites for SARS-CoV-2 samples with nasopharynx being the benchmark.

Study design: COVID-19 positive patients were recruited prospectively, and samples were collected and analysed for SARS-CoV-2 with RT-PCR from all four anatomical sites in 43 patients, who provided written informed consent.

Results: All anterior nasal and saliva samples were positive, while two oropharyngeal samples were negative. There was no significant difference in the cycle threshold values of nasopharyngeal and anterior nasal samples while saliva and oropharynx had higher cycle threshold values.

Conclusions: Anterior nasal swab performs as good as nasopharynx swab with saliva also finding all the positives but with higher cycle threshold values. Thus, we can conclude that anterior nasal swabs can be used for SARS-CoV-2 detection instead of nasopharyngeal swabs if the situation would require so.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • COVID-19 Testing
  • COVID-19*
  • Finland
  • Reverse Transcriptase Polymerase Chain Reaction
  • SARS-CoV-2

Grants and funding

This work was supported by funding from Tampere Tuberculosis Foundation; Research Foundation of the Pulmonary Diseases; Competitive State Research Financing of the Expert Responsibility area of Tampere University Hospital; Tampere University Hospital Support Foundation. Funders did not have any role in any part of the study. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.