Detection of severe acute respiratory coronavirus virus 2 (SARS-CoV-2) in outpatients: A multicenter comparison of self-collected saline gargle, oral swab, and combined oral-anterior nasal swab to a provider collected nasopharyngeal swab.

Christopher E Kandel,Mihaela Anca Serbanescu,Allison Mcgeer,Matthew Young,Hilary Racher,Kevin Katz,Christie Vermeiren,Dorothy Quon,Lee W Goneau,Jeff E Powis,Elena Sheldrake,Omid Kyle Vojdani,James Callahan,David Bulir,Janine Mccready

doi:10.1017/ice.2021.2

Abstract

Widespread testing for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) is necessary to curb the spread of coronavirus disease 2019 (COVID-19), but testing is undermined when the only option is a nasopharyngeal swab. Self-collected swab techniques can overcome many of the disadvantages of a nasopharyngeal swab, but they require evaluation. Three self-collected non-nasopharyngeal swab techniques (saline gargle, oral swab and combined oral-anterior nasal swab) were compared to a nasopharyngeal swab for SARS-CoV-2 detection at multiple COVID-19 assessment centers in Toronto, Canada. The performance characteristics of each test were assessed. The adjusted sensitivity of the saline gargle was 0.90 (95% CI 0.86-0.94), the oral swab was 0.82 (95% CI, 0.72-0.89) and the combined oral-anterior nasal swab was 0.87 (95% CI, 0.77-0.93) compared to a nasopharyngeal swab, which demonstrated a sensitivity of ˜90% when all positive tests were the reference standard. The median cycle threshold values for the SARS-CoV-2 E-gene for concordant and discordant saline gargle specimens were 17 and 31 (P < .001), for the oral swabs these values were 17 and 28 (P < .001), and for oral-anterior nasal swabs these values were 18 and 31 (P = .007). Self-collected saline gargle and an oral-anterior nasal swab have a similar sensitivity to a nasopharyngeal swab for the detection of SARS-CoV-2. These alternative collection techniques are cheap and can eliminate barriers to testing, particularly in underserved populations.

Highlights

Widespread testing for severe acute respiratory coronavirus virus 2 (SARS-CoV-2) is necessary to curb the spread of coronavirus disease 2019 (COVID-19), but testing is undermined when the only option is a nasopharyngeal swab
Of 19,620 nasopharyngeal swabs performed in the 3 separate study periods (14,491 for saline gargle, 3,542 for oral swab and 1,587 for oral–anterior nose swab), 340 individuals were positive for SARSCoV-2
Saliva is effective for SARS-CoV-2 detection with an overall sensitivity of 0.91.4

Summary

Methods

The study population was consecutive individuals presenting to 3 assessment centers in Toronto, Ontario, who had a nasopharyngeal swab obtained for SARS-CoV-2 testing. During 3 separate study periods, a self-collected paired non-nasopharyngeal specimen was requested: saline gargle from August to September 25, 2020; oral swab from September to October 3, 2020; and a combined oral–anterior nasal swab from October 14 to 17, 2020. Individuals self-swabbed the back of their tongue, buccal mucosa, coat the swab in saliva. For the combined oral–anterior nasal swab, each individual self-swabbed the back of their tongue, buccal mucosa, and the anterior aspect of both nares (for complete instructions see the Supplementary Material online). The swab used for the latter 2 techniques was the Miraclean Technology disposable flocked nasal, oral, and throat swab. All specimens were stored at 4°C until testing. This study was approved by the Michael Garron Hospital Research Ethics Board with implied consent for the voluntary selfcollection of a second test after the study rationale was explained

Study design

Results

Discussion