1. A combined oro-nasopharyngeal swab is more sensitive than mouthwash in detecting SARS-CoV-2 by a high-throughput PCR assay.
- Author
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Michel, Wiebke, Färber, Jacqueline, Dilas, Milica, Heuft, Hans-Gert, Tammer, Ina, Baar, Jannik, and Kaasch, Achim J.
- Subjects
COVID-19 ,MOUTHWASHES ,AUTOANALYZERS ,RESPIRATORY infections ,REFUGEES ,DESCRIPTIVE statistics ,COVID-19 testing ,POLYMERASE chain reaction ,COLLECTION & preservation of biological specimens ,OROPHARYNX - Abstract
Objectives: The optimal diagnostic specimen to detect SARS-CoV-2 by PCR in the upper respiratory tract is unclear. Mouthwash fluid has been reported as an alternative to nasopharyngeal and oropharyngeal swabs. We compared mouthwash fluid with a combined oro-nasopharyngeal swab regarding test performance. Methods: In a large refugee facility, we retested individuals with a previous positive test for SARS-CoV-2 and their quarantined close contacts. All individuals were asymptomatic at the time of testing. First, a mouthwash (gargling for at least 5 s) with sterile water was performed. Then, with a single flocked swab the back of the throat and subsequently the nasopharynx were sampled. Samples were inactivated and analysed on a Roche cobas 6800
® system with the Roche SARS-CoV-2 test. Results: Of 76 individuals, 39 (51%) tested positive for SARS-CoV-2 by oro-nasopharyngeal swab. Mouthwash detected 13 of 76 (17%) infections, but did not detect any additional infection. Samples that were positive in both tests, had lower cycle threshold (Ct)-values for oro-nasopharyngeal samples, indicating a higher virus concentration, compared to samples only positive in oro-nasopharyngeal swabs. Conclusion: Mouthwash is not as sensitive as combined oro-nasopharyngeal swab in detecting upper respiratory tract infection. [ABSTRACT FROM AUTHOR]- Published
- 2021
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