Journal of Preventive Medicine

Saliva as an Alternate Specimen Source for the Diagnosis of Coronavirus Disease 2019 in Symptomatic Patients Using Cepheid Xpert Xpress SARS-CoV-2

Background: Rapid and accurate SARS-CoV-2 diagnostic testing is essential for controlling the ongoing COVID-19 pandemic. The current gold standard for COVID-19 diagnosis is real-time polymerase chain reaction (RT-PCR) detection of SARS-CoV-2 from nasopharyngeal swab specimens. The objective of this study is to assess saliva specimens for the diagnosis of COVID-19 by using the Gene Xpert® Xpress SARS-CoV-2 assay.

Methods: In June 2020 we prospectively simultaneously collected saliva samples and a standard nasopharyngeal swab from 60 patients meeting case definition of COVID-19 in the Emergency Department and from inpatients in Rashid Hospital at Dubai Health Authority during the outbreak of COVID-19. Real-time RT-PCR using the Cepheid Xpert Xpress SARS-CoV-2 was performed, and the results of the two specimens were compared.

Results: A total of 60 paired nasopharyngeal swab and saliva specimens were tested. An analysis of the agreement between the two specimens demonstrated 97% observed agreement. 30/28 samples were positive in saliva when compared to the NPS resulting in a positive percent agreement of 93%. 30/32 samples had a negative saliva and NPS. Two samples demonstrated detectable levels of SARS CoV-2 nucleic acid in the saliva, but the NPS were negative, resulting in a negative percent agreement of 94%.

Conclusion: Our data showed that saliva is an acceptable sensitive and specific alternative source for detecting SARS CoV-2 nucleic acid and the use of saliva samples is safer and more convenient for the patient. Nasopharyngeal swab sampling inconsistency may be one of the potential issues for false negatives results.

Author(s):

Maya Habous, Rania Medhat Seliem, Laila AlDabal, Firas Al-Najjar, Maimona Elimam, Meera Jainmboo, Bayan Abdalla, Zahra Abdullahi, Ayesha Nasser

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