Frontiers in Medicine (Feb 2021)

Performance of Saliva Samples for COVID-19 Diagnosis by Using the AllplexTM 2019-nCoV Assay Kit

  • Cecilia V. Tapia,
  • Campos Marcia,
  • Mora Ivone,
  • Pozas Nadia,
  • Morales Lesly,
  • Guzmán Camila,
  • Aguilera Valentina,
  • Ibarra Paula,
  • Magne Fabien

DOI
https://doi.org/10.3389/fmed.2021.617399
Journal volume & issue
Vol. 8

Abstract

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Background: Although the nasopharyngeal swab (NPS) is the reference sampling method for the detection of SARS-Cov-2, it is not always possible to collect NPS in some patients. Saliva represents an interesting sampling method because it is less invasive and more convenient in patients with nasal or pharyngeal lesions.Objective: To compare the RT-qPCR test performances of saliva samples with nasal mid-turbinate swab (NMTS) and NPS samples in a cohort of ambulatory patients suspected of having COVID-19.Study Design: For each of the 112 enrolled patients, NPS, NMTS, and saliva samples were collected and tested for SARS-Cov-2 detection using three different target genes (RdRP, N and E genes) by RT-qPCR.Results: Among the positive samples (56/112), saliva samples showed a lower percentage of SARS-Cov-2 detection compared to NPS samples, (85.7 vs. 96.4%), while still a lower percentage was observed for NMTS samples (78.6%). In average, saliva samples showed higher Ct values for all tested target genes, compared to those from NPS and NMTS samples.Conclusions: By using the AllplexTM 2019-nCoV Assay Kit, saliva samples showed lower sensitivity for SARS CoV-2 compared to NPS samples; however, the not detected cases had lower viral burden in NPS samples (CT values >33) representing an interesting alternative sampling method in patients in which it is not possible to take a NPS sample.

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