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. 2021 May;93(5):3268-3272.
doi: 10.1002/jmv.26839. Epub 2021 Feb 23.

Self-collected saliva for SARS-CoV-2 detection: A prospective study in the emergency room

Marcela Echavarria  1   2 , Noelia S Reyes  1 , Pamela E Rodriguez  1 , Martin Ypas  3 , Carmen Ricarte  1 , María P Rodriguez  3 , Matias G Perez  3 , Alejandro Seoane  3 , Alfredo Martinez  2 , Cristina Videla  2 , Martin E Stryjewski  4 , Guadalupe Carballal  1
Affiliations

Self-collected saliva for SARS-CoV-2 detection: A prospective study in the emergency room

Marcela Echavarria et al. J Med Virol. 2021 May.

Abstract

Current diagnostic standards involve severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection in nasopharyngeal swabs (NPS), but saliva is an attractive and noninvasive option for diagnosis. The objectives were to determine the performance of saliva in comparison with NPS for detecting SARS-CoV-2 and to compare the optimized home brew reverse-transcription polymerase chain reaction (RT-PCR) with a commercial RT-PCR. Paired NPS and saliva specimens were prospectively collected and tested by RT-PCR from patients presenting at an emergency room with signs and symptoms compatible with coronavirus disease-2019. A total of 348 samples from 174 patients were tested by RT-PCR assays. Among 174 patients with symptoms, 63 (36%) were SARS-CoV-2 positive in NPS using the optimized home-brew PCR. Of these 63 patients, 61 (98%) were also positive in saliva. An additional positive SARS-CoV-2 saliva was detected in a patient with pneumonia. Kappa Cohen's coefficient agreement between NPS and saliva was 0.96 (95% confidence interval [CI], 0.90-0.99). Median Ct values in NPS versus saliva were 18.88 (interquartile range [IQR], 15.60-23.58; range, 11.97-38.10) versus 26.10 (IQR, 22.75-30.06; range, 13.78-39.22), respectively (p < .0001). The optimized home-brew RT-PCR demonstrated higher analytical and clinical sensitivity compared with the commercial RT-PCR assay. A high sensitivity (98%) and agreement (kappa 0.96) in saliva samples compared to NPS was demonstrated when using an optimized home-brew PCR even when the viral load in saliva was lower than in NPS. This noninvasive sample is easy to collect, requires less consumable and avoids discomfort to patients. Importantly, self-collection of saliva can diminish exposure to healthcare personnel.

Keywords: COVID 19; PCR; SARS-CoV-2; nasopharyngeal swab; saliva.

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Conflict of interest statement

Martin Stryjewski is a consultant to Basilea, a speaker for Pfizer and principal investigator in Argentina for NIH grant UM1AI104681. The rest of the authors have no conflict of interest.

Figures

Figure 1
Figure 1
SARS‐CoV‐2 Ct in saliva and nasopharyngeal swabs (NPS). (A) Ct median from positive nasopharyngeal swabs (n = 63) and saliva samples (n = 62) were compared (p < .0001). (B) Patients matched positive and discrepant samples (n = 64) represented by the connecting lines were compared by a Wilcoxon rank sum test (p < .0001). SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2
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