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. 2021 Sep-Oct:43:102144.
doi: 10.1016/j.tmaid.2021.102144. Epub 2021 Jul 21.

Diagnostic accuracy of fresh drooled saliva for SARS-CoV-2 in travelers

Alif Adlan Mohd Thabit  1 , Kalaiarasu M Peariasamy  2 , Pei Xuan Kuan  3 , Denisa Khoo Fern Ying  4 , Nelson Nheu  5 , Camille Cyncynatus  5 , Muhamad Afiq Mu'iz Arifin  1 , Amira Naziffa Shamsuddin  1 , Mohd Asri Yamin  6 , Muhammad Ashraf Mohd Padzil  1 , Ganeswrie Rajasekaram  5 , Martin Giddy  5 , Sivasooriar Sivaneson  5 , Harvinder Kaur Lakhbeer Singh  5 , Adleen Azman  5 , Afifah Haji Hassan  6 , Suresh Kumar Chidambaram  1
Affiliations

Diagnostic accuracy of fresh drooled saliva for SARS-CoV-2 in travelers

Alif Adlan Mohd Thabit et al. Travel Med Infect Dis. 2021 Sep-Oct.

Abstract

Background: The standard for SARS-CoV-2 diagnosis is RT-PCR from nasopharyngeal or oropharyngeal swabs. Major airports require COVID-19 screening, and saliva has the potential as a substitute specimen for SARS-CoV-2 diagnosis. We investigated the utility of fresh drooled saliva against NPS for COVID-19 screening of travelers.

Methods: We recruited 81 travelers and 15 non-travelers (including ten controls) prospectively within a mean of 3·22 days of RT-PCR confirmed COVID-19. Each study participant provided 2 mls of early morning fresh drooled whole saliva separately into a sterile plastic container and GeneFiX™ saliva collection kit. The saliva specimens were processed within 4 h and tested for SARS-CoV-2 genes (E, RdRP, and N2) and the results compared to paired NPS RT-PCR for diagnostic accuracy.

Results: Majority of travellers were asymptomatic (75·0%) with a mean age of 34·26 years. 77 travelers were RT-PCR positive at the time of hospitalization whilst three travelers had positive contacts. In this group, the detection rate for SARS-CoV-2 with NPS, whole saliva, and GeneFiX™ were comparable (89·3%, 50/56; 87·8%, 43/49; 89·6%, 43/48). Both saliva collection methods were in good agreement (Kappa = 0·69). There was no statistical difference between the detection rates of saliva and NPS (p > 0·05). Detection was highest for the N2 gene whilst the E gene provided the highest viral load (mean = 27·96 to 30·10, SD = 3·14 to 3·85). Saliva specimens have high sensitivity (80·4%) and specificity (90·0%) with a high positive predictive value of 91·8% for SARS-CoV-2 diagnosis.

Conclusion: Saliva for SARS-CoV-2 screening is a simple accurate technique comparable with NPS RT-PCR.

Keywords: Aviation; COVID-19; Ct. value; RT-PCR; Travel medicine.

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Figures

Fig. 1
Fig. 1
(L to R) Sterile plastic container, GeneFiX™ saliva collection kit and nasopharyngeal swab collection kit.
Fig. 2
Fig. 2
Comparison of Ct. values of saliva specimens between travelers and non-travelers.
Fig. 3
Fig. 3
Concordance of saliva specimens among travelers.
Fig. 4
Fig. 4
Receiver Operating Characteristic (ROC) curve for saliva specimens vs. nasopharyngeal swab specimens.
See this image and copyright information in PMC

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