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. 2021 Mar:104:255-261.
doi: 10.1016/j.ijid.2020.12.080. Epub 2021 Jan 2.

Validation of self-collected buccal swab and saliva as a diagnostic tool for COVID-19

Chee Wai Ku  1 , Durai Shivani  2 , Jacqueline Q T Kwan  3 , See Ling Loy  4 , Christina Erwin  5 , Karrie K K Ko  6 , Xiang Wen Ng  7 , Lynette Oon  8 , Koh Cheng Thoon  9 , Shirin Kalimuddin  10 , Jerry K Y Chan  11
Affiliations

Validation of self-collected buccal swab and saliva as a diagnostic tool for COVID-19

Chee Wai Ku et al. Int J Infect Dis. 2021 Mar.

Abstract

Background: Effective management of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires large-scale testing to identify and isolate infectious carriers. Self-administered buccal swab and saliva collection are convenient, painless, and safe alternatives to the current healthcare worker (HCW)-collected nasopharyngeal swab (NPS).

Methods: A cross-sectional single-centre study was conducted on 42 participants who had tested positive for SARS-CoV-2 via an NPS within the past 7 days. Real-time polymerase chain reaction (RT-PCR) was performed and cycle threshold (Ct) values were obtained for each test. The positive percent agreement (PPA), negative percent agreement (NPA), and overall agreement (OA) were calculated for the saliva samples and buccal swabs, and compared with NPS.

Results: Among the 42 participants, 73.8% (31/42) tested positive by any one of the three tests. With reference to NPS, the saliva test had PPA 66.7%, NPA 91.7%, and OA 69.0%; the buccal swab had PPA 56.7%, NPA 100%, and OA 73.8%.

Conclusion: Self-collected saliva tests and buccal swabs showed only moderate agreement with HCW-collected NPS. Primary screening for SARS-CoV-2 may be performed with a saliva test or buccal swab, with a negative test warranting a confirmatory NPS to avoid false-negatives, minimize discomfort, and reduce the risk of spread to the community and HCWs.

Keywords: Buccal swab; COVID-19; Diagnostic tests; SARS-CoV-2; Saliva test.

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Figures

Figure 1
Figure 1
Comparison of cycle threshold values between nasopharyngeal swabs and buccal swabs (A) and between nasopharyngeal swabs and saliva samples (B). Error bars represent 95% confidence intervals of the mean values. The p-value was based on the paired t-test.
Figure 2
Figure 2
Associations between cycle threshold values (Ct) of nasopharyngeal, buccal, and saliva tests with the time since symptom onset from : Ct of nasopharyngeal swab and days: r = 0.14 (p = 0.485); Ct of buccal swab and days: r = 0.07 (p = 0.806); Ct of saliva sample and days: r = 0.171 (p = 0.471).
Figure 3
Figure 3
Comparison of cycle threshold values (Ct) for paired nasopharyngeal swab, saliva sample, and buccal swab RT-PCR performed on SARS-CoV-2-positive patients.
Figure 4
Figure 4
Recommended clinical workflow for population SARS-CoV-2 screening.
See this image and copyright information in PMC

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