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Saliva is a reliable, non-invasive specimen for SARS-CoV-2 detection.

Author(s): Vaz SN, Santana DS, Netto EM, Pedroso C, Wang WK, Santos FDA, Brites C

Publication: Braz J Infect Dis, 2020, Vol. 24, Page 422-427

PubMed ID: 32888905 PubMed Review Paper? No

Purpose of Paper

Conclusion of Paper

Studies

1. Study Purpose

   This study compared the detection of SARS-CoV-2, the virus that causes the novel 2019 coronavirus disease (COVID, COVID-19, COVID19), in self-collected saliva specimens with healthcare worker–collected nasopharyngeal and/or oropharyngeal swab specimens. Specimens were collected from 149 participants presenting with signs/symptoms suggesting SARS-CoV-2 infection aged 33-48 y (46 males, 103 females; mean age=40 y). Saliva was self-collected by patients by repeatedly spitting into a sterile urine cup until approximately 2 mL were obtained. Nasopharyngeal and/or oropharyngeal swab specimens were collected by healthcare-workers (details not provided). Specimens were transported in a thermal box (2-8°C) to the lab and then stored at -80°C until analysis. Viral RNA was extracted using the QIAamp RNA Mini Kit and quantified by real-time qRT-PCR using primer/probe sets for SARS-CoV-2 E and RdRp genes. Results were classified as positive when both genes were detected with a cycle threshold (CT) ≤40. Twenty days after onset of symptoms, blood was collected by an unspecified method from participants that tested positive in the nasopharyngeal/oropharyngeal swab specimen but negative in the saliva specimen (n=4) and analyzed for anti-SARS-CoV-2 antibodies.

   Summary of Findings:

   The detection rate of SARS-CoV-2 RNA was slightly lower in saliva than nasopharyngeal/oropharyngeal swab specimens (43.22% versus 45.8%, overall agreement of 96.1%) but differences did not reach statistical significance. Of the six participants with discordant results, virus was detected only in the saliva of two participants and detected only in the nasopharyngeal/oropharyngeal swab in the remaining four participants. Using the swab specimens as the standard, the sensitivity, specificity, positive predictive value, and negative predictive value of real-time qRT-PCR using saliva were 94.4%, 97.62%, 97.1%, and 95.35%; respectively. Of the four participants with negative saliva results but positive results from the nasopharyngeal/oropharyngeal swab, one was negative for SARS-CoV-2 IgG in the blood 20 days after symptom onset.

   Biospecimens

   • Bodily Fluid - Saliva
   • Cell - Nasopharynx
   • Cell - Oral Cavity

   Preservative Types

   • Frozen

   Diagnoses:

   • Pneumonia/Respiratory Infection

   Platform:

   Analyte	Technology Platform
   Protein	ELISA
   RNA	Real-time qRT-PCR

   Pre-analytical Factors:

   Classification	Pre-analytical Factor	Value(s)
   Real-time qRT-PCR Specific	Targeted nucleic acid	SARS-CoV-2 E gene SARS-CoV-2 RdRp gene
   Biospecimen Acquisition	Biospecimen location	Saliva Nasopharynx Oropharynx

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