Evaluating Diagnostic Accuracy of Saliva Sampling Methods for Severe Acute Respiratory Syndrome Coronavirus 2 Reveals Differential Sensitivity and Association with Viral Load

Abstract

Nasopharyngeal swabs are considered the preferential collection method for SARS-CoV-2 diagnostics. Alternative sampling procedures that are less invasive and do not require a healthcare professional, such as saliva collection, would be more preferable. We compared saliva specimens and nasopharyngeal (NP) swabs with respect to sensitivity in detecting SARS-CoV-2. We obtained a nasopharyngeal and two saliva specimens (collected by spitting or oral swabbing) from more than 2500 individuals. All samples were tested by RT-qPCR detecting RNA of SARS-CoV-2. We compared the test sensitivity on the two saliva collections with the nasopharyngeal specimen for all subjects and stratified by symptom status and viral load. Of the 2850 patients for which all three samples were available, 105 were positive on NP, whereas 32 and 23 were also positive on saliva spitting and saliva swabbing samples, respectively. The sensitivity of the RT-qPCR to detect SARS-CoV-2 among NP-positive patients was 30.5% (95% CI=1.9%-40.2%) for saliva spitting, and 21.9% (95% CI=14.4%-31.0%) for saliva swabbing. However, when focusing on subjects with medium to high viral load, sensitivity on saliva increased substantially: 93.9% (95% CI=79.8%-99.3%) and 76.9% (95% CI=56.4-91.0) for spitting and swabbing, respectively, regardless of symptomatic status. Our results suggest that saliva cannot readily replace nasopharyngeal sampling for SARS-CoV-2 diagnostics but may enable identification of the most contagious cases with medium to high viral loads.

Nasopharyngeal swabs vs. saliva sampling for SARS-CoV-2 detection: A cross-sectional survey of acceptability for caregivers and children after experiencing both methods

“…The actual difference in sensitivity between saliva sampling and nasopharyngeal swabs is not definitively known at present, and likely varies in different clinical scenarios. While initial meta-analyses have estimated sensitivity of saliva samples to be similar to nasopharyngeal swabs [3,4], Mestdagh et al [14] found that sensitivity varied widely according to saliva collection technique…”

Salivary Aspartate Aminotransferase, Alanine Aminotransferase and IgA as biomarkers for Type I Diabetes Mellitus: A Systematic Review

“…Local factors such as increased plaque accumulation and calculus deposition could also be responsible for elevated IgA in these patients. 18, 19 In their study, Mestdagh et al 20 postulated that overexpression of salivary IgA in T1DM patients could be due to the presence of specific anti-insulin and anti- Streptococcus mutans antibodies. However, none of the included studies assessed the sensitivity, specificity and diagnostic accuracy of salivary IgA in T1DM patients.…”

Plasma SARS‐CoV‐2 RNA elimination and RAGE kinetics distinguish COVID‐19 severity

“…Particular attention has been paid to clinical and immunological characteristics of severity, as dysregulated and dysfunctional immune responses are characteristic of poor outcomes 5,6 . Viral loads measured by nasopharyngeal swabs, 7,8 bronchioalveolar lavage, 9 saliva, 10 and at autopsy 11 have also been investigated for their association with SARS‐CoV‐2 infectivity and COVID‐19 severity. In that vein, we have previously established that high plasma viral RNA (vRNA) loads in acute infection courses are tightly associated with fatal outcomes in hospitalised patients with COVID‐19 12 .…”

“…5,6 Viral loads measured by nasopharyngeal swabs, 7,8 bronchioalveolar ª 2023 The Authors. Clinical & Translational Immunology published by John Wiley & Sons Australia, Ltd on behalf of lavage, 9 saliva, 10 and at autopsy 11 have also been investigated for their association with SARS-CoV-2 infectivity and COVID-19 severity. In that vein, we have previously established that high plasma viral RNA (vRNA) loads in acute infection courses are tightly associated with fatal outcomes in hospitalised patients with COVID-19.…”