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. 2021 Mar 19;59(4):e02427-20.
doi: 10.1128/JCM.02427-20. Print 2021 Mar 19.

Self-Collected Saline Gargle Samples as an Alternative to Health Care Worker-Collected Nasopharyngeal Swabs for COVID-19 Diagnosis in Outpatients

David M Goldfarb  1   2 , Peter Tilley  3   2 , Ghada N Al-Rawahi  3   2 , Jocelyn A Srigley  3   2 , Geoffrey Ford  4 , Heather Pedersen  4 , Abhilasha Pabbi  5 , Stephanie Hannam-Clark  5 , Marthe Charles  3   6 , Michelle Dittrick  3 , Vijay J Gadkar  3   2 , Jeffrey M Pernica  7 , Linda M N Hoang  3   8
Affiliations

Self-Collected Saline Gargle Samples as an Alternative to Health Care Worker-Collected Nasopharyngeal Swabs for COVID-19 Diagnosis in Outpatients

David M Goldfarb et al. J Clin Microbiol. .

Abstract

We assessed the performance, stability, and user acceptability of swab-independent self-collected saliva and saline mouth rinse/gargle sample types for the molecular detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in adults and school-aged children. Outpatients who had recently been diagnosed with COVID-19 or were presenting with suspected COVID-19 were asked to have a nasopharyngeal (NP) swab collected and provide at least one self-collected sample type. Participants were also asked about sample acceptability using a five-point Likert scale. For those previously diagnosed with COVID-19, all samples underwent real-time PCR testing using a lab-developed assay, and the majority were also tested using an FDA-authorized assay. For those presenting with suspected COVID-19, only those with a positive nasopharyngeal swab sample went on to have other samples tested. Saline mouth rinse/gargle and saliva samples were tested daily at time zero, day 1, and day 2 to assess nucleic acid stability at room temperature. Fifty participants (aged 4 to 71 years) were included; of these, 40 had at least one positive sample and were included in the primary sample yield analysis. Saline mouth rinse/gargle samples had a sensitivity of 98% (39/40), while saliva samples had a sensitivity of 79% (26/33). Both saline mouth rinse/gargle and saliva samples showed stable viral RNA detection after 2 days of room temperature storage. Mouth rinse/gargle samples had the highest (mean, 4.9) and health care worker (HCW)-collected NP swabs had the lowest acceptability scores (mean, 3.1). In conclusion, saline mouth rinse/gargle samples demonstrated higher combined user acceptability ratings and analytical performance than saliva and HCW-collected NP swabs. This sample type is a promising swab-independent option, particularly for outpatient self-collection in adults and school-aged children.

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

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Figures

FIG 1
FIG 1
Proportion of samples testing positive based on time from initial COVID-19 diagnosis. NPS, nasopharyngeal swab.
FIG 2
FIG 2
Threshold cycle (CT) values across different sample types at baseline. NPFS, nasopharyngeal flocked swab.
FIG 3
FIG 3
Stability of SARS-CoV-2 RNA detection. Shown are threshold cycle values at baseline, day 1, and day 2 for saline gargle and saliva samples with positive values.
See this image and copyright information in PMC

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