The Accuracy of Healthcare Worker versus Self Collected (2-in-1) Oropharyngeal and Bilateral Mid-Turbinate (OPMT) Swabs and Saliva Samples for SARS-CoV-2

Tan, Seow Yen; Tey, Hong Liang; Lim, Ernest Tian Hong; Toh, Song Tar; Chan, Yiong Huak; Tan, Pei Ting; Lee, Sing Ai; Tan, Cheryl Xiaotong; Koh, Gerald Choon Huat; Tan, Thean Yen; Siau, Chuin

Background Self-sampling for SARS-CoV-2 would significantly raise testing capacity and reduce healthcare worker (HCW) exposure to infectious droplets personal, and protective equipment (PPE) use. Methods We conducted a diagnostic accuracy study where subjects with a confirmed diagnosis of COVID-19 (n=401) and healthy volunteers (n=100) were asked to self-swab from their oropharynx and mid-turbinate (OPMT), and self-collect saliva. The results of these samples were compared to an OPMT performed by a HCW in the same patient at the same session. Results In subjects confirmed to have COVID-19, the detection rates of the HCW-swab, self-swab, saliva, and combined self-swab plus saliva samples were 82.8%, 75.1%, 74.3% and 86.5% respectively. All samples obtained from healthy volunteers were tested negative. Compared to HCW-swab, the detection rates of a self-swab sample and saliva sample were inferior by 8.7% (95%CI: 2.4% to 15.0%, p=0.006) and 9.5% (95%CI: 3.1% to 15.8%, p=0.003) respectively. The combined detection rate of self-swab and saliva had a higher detection rate of 2.7% (95%CI: -2.6% to 8.0%, p=0.321). The sensitivity of both the self-collection methods are higher when the Ct value of the HCW swab is less than 30. The negative correctness of both the self-swab and saliva testing was 100% (95% CI 96.4% to 100%). Conclusion Our study provides evidence that detection rates of self-collected OPMT swab and saliva samples were inferior to a HCW swab, but they could still be useful testing tools in the appropriate clinical settings.