Abstract
Background: Although the nasopharyngeal swab (NPS) is the reference sampling method for the detection of SARS-Cov-2, it is not always possible to collect NPS in some patients. Saliva represents an interesting sampling method because it is less invasive and more convenient in patients with nasal or pharyngeal lesions.Objective: To compare the RT-qPCR test performances of saliva samples with nasal mid-turbinate swab (NMTS) and NPS samples in a cohort of ambulatory patients suspected of having COVID-19.Study Design: For each of the 112 enrolled patients, NPS, NMTS, and saliva samples were collected and tested for SARS-Cov-2 detection using three different target genes (RdRP, N and E genes) by RT-qPCR.Results: Among the positive samples (56/112), saliva samples showed a lower percentage of SARS-Cov-2 detection compared to NPS samples, (85.7 vs. 96.4%), while still a lower percentage was observed for NMTS samples (78.6%). In average, saliva samples showed higher Ct values for all tested target genes, compared to those from NPS and NMTS samples.Conclusions: By using the AllplexTM 2019-nCoV Assay Kit, saliva samples showed lower sensitivity for SARS CoV-2 compared to NPS samples; however, the not detected cases had lower viral burden in NPS samples (CT values >33) representing an interesting alternative sampling method in patients in which it is not possible to take a NPS sample.
Highlights
COVID-19 diagnosis is based on clinical, laboratory, and imaging features through computed tomography (CT) [1,2,3]
nasopharyngeal swab (NPS) and nasal midturbinate swab (NMTS) samples were collected using a standard technique, as recommended by the manufacturer (AllplexTM 2019-nCoV Assay insert), and transported to the laboratory in a viral transport medium that was prepared according to the standard operating procedure of the Centers for Disease Control and Prevention (CDC) in the United States
We found that 39/56 samples (64.2%) were positive for all the three sample types, 3/56 samples (5.4%) for both NPS and NMTS samples, and 5/56 samples (8.9%) for both NPS and saliva samples
Summary
COVID-19 diagnosis is based on clinical, laboratory, and imaging features through computed tomography (CT) [1,2,3]. It is not possible to collect NPS in some patients, such as those with epistaxis or with an inflamed nasopharyngeal mucous membrane. Performance of Saliva Samples for SARS-Cov-2 Detection controlled with PCR to be able to go to work, and they suffer discomforts due to sampling. This sampling method can constitute a risk in patients with thrombocytopenia and other coagulation disorders [1]. The nasopharyngeal swab (NPS) is the reference sampling method for the detection of SARS-Cov-2, it is not always possible to collect NPS in some patients. Saliva represents an interesting sampling method because it is less invasive and more convenient in patients with nasal or pharyngeal lesions
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