Related Experiment Video
Updated: Oct 17, 2025
Efficient SARS-CoV-2 Quantitative Reverse Transcriptase PCR Saliva Diagnostic Strategy utilizing Open-Source Pipetting Robots
Published on: February 11, 2022
Natural spring water gargle and direct RT-PCR for the diagnosis of COVID-19 (COVID-SPRING study)
Jeannot Dumaresq1, François Coutlée2, Philippe J Dufresne3
1Département de Microbiologie et d'Infectiologie, CISSS de Chaudière-Appalaches, Lévis, Québec, Canada; Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, Québec, Canada.
Background:
Nasopharyngeal swab has long been considered the specimen of choice for the diagnosis of respiratory viral infections, including SARS-CoV-2 infection, but it suffers from several drawbacks: its discomfort limits screening acceptability, and it is vulnerable to shortages in both specialized materials and trained healthcare workers in the context of a pandemic.
Methods:
We prospectively compared natural spring water gargle to combined oro-nasopharyngeal swab (ONPS) for the diagnosis of coronavirus disease 2019 (COVID-19) in paired clinical specimens (1005 ONPS and 1005 gargles) collected from 987 unique early symptomatic as well as asymptomatic individuals from the community.
Results:
Using a direct RT-PCR method with the Allplex™ 2019-nCoV Assay (Seegene), the clinical sensitivity of the gargle was 95.3% (95% confidence interval [CI], 90.2 - 98.3%), similar to the sensitivity of the ONPS (93.8%; 95% CI, 88.2 - 97.3%), despite significantly lower viral RNA concentration in gargles, as reflected by higher cycle threshold values. No single specimen type detected all COVID-19 cases. SARS-CoV-2 RNA was stable in gargles at room temperature for at least 7 days.
Conclusion:
The simplicity of this sampling method coupled with the accessibility of spring water are clear advantages in a pandemic situation where testing frequency, turnaround time and shortage of consumables and trained staff are critical elements.
