Saliva is Comparable to Nasopharyngeal Swabs for Molecular Detection of SARS-CoV-2

Callahan, Cody; Ditelberg, Sarah; Dutta, Sachinandan; Littlehale, Nancy; Cheng, Annie; Kupczewski, Kristin; McVay, Danielle; Riedel, Stefan; Arnaout, Ramy

doi:10.1128/spectrum.00162-21

Cited by 35 publications

(21 citation statements)

References 24 publications

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“…Saliva is commonly used to diagnose viruses similar to SARS-CoV-2 and has been suggested as appropriate for the diagnosis of COVID-19 [6,12,15,17,[19][20][21] but the detection method still needs improvement. Until now, saliva testing was less sensitive than nasopharyngeal swab [22], however recent studies have reported similar results for saliva and nasopharyngeal swabs [23]. The collection of saliva is non-invasive and can be performed by the patient him/herself, reducing the risk of cross-contamination and the need of specialized healthcare workers.…”

Section: Introductionmentioning

confidence: 99%

Population wide testing pooling strategy for SARS-CoV-2 detection using saliva

et al. 2022

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SARS-CoV-2 pandemic has forced frequent testing of populations. It is necessary to identify the most cost-effective strategies for the detection of COVID-19 outbreaks. Nasopharyngeal samples have been used for SARS-CoV-2 detection but require a healthcare professional to collect the sample and cause discomfort and pain to the individual. Saliva has been suggested as an appropriate fluid for the diagnosis of COVID-19. We have investigated the possibility of using pools of saliva samples to detect SARS-CoV-2 in symptomatic and asymptomatic patients. Two hundred and seventy-nine saliva samples were analyzed through RT-PCR of Envelope, Nucleocapsid and Open Reading Frame 1ab genes. Reproducibility assays showed an almost perfect agreement as well as high sensitivity (96.6%), specificity (96.8%), positive predicted value (96.6%), and negative predicted value (96.8%). The average Cycle Threshold of the genes detected was 29.7. No significant differences (p > 0.05) were detected when comparing the cycle threshold average of two consecutive reactions on the same positive saliva samples. Saliva samples have a higher median viral load (32.6) than in nasopharyngeal samples (28.9), although no significant differences were detected (p > 0.05). Saliva-pool samples allowed effective SARS-CoV-2 screening, with a higher sensibility (96.9%) on 10-sample pools than in 20-sample pools (87.5%). Regardless of pools size specificity was high (99.9%) and an almost perfect agreement was observed. Our strategy was successfully applied in population wide testing of more than 2000 individuals, showing that it is possible to use pooled saliva as diagnostic fluid for SARS-CoV-2 infection.

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Section: Introductionmentioning

confidence: 99%

Population wide testing pooling strategy for SARS-CoV-2 detection using saliva

et al. 2022

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“…This circumstance caused a high impact on daily life, including dentistry and oral hygiene issues [ 1 ]. The virus SARS-CoV-2 is mainly located in the nasopharyngeal tract as a main source for transmission, while the oral cavity and saliva also contains a certain amount of viral load, which is, however, of little value for airborne transmission of the virus [ 2 ]. Accordingly, oral hygiene issues were repeatedly and comprehensively discussed in context of the current pandemic situation.…”

Section: Introductionmentioning

confidence: 99%

The role of toothbrush in the transmission of corona- and influenza viruses — results of an in vitro study

et al. 2022

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Objectives The aim of this in vitro study was to investigate viruses’ stabilities on manual toothbrushes using feline coronavirus (FeCoV) as representative of coronaviruses and an Avian influenza A virus H1N1 for influenza viruses. Material and methods Two viruses, FeCoV (Strain Munich; titer 107.5 TCID50/ml) and H1N1 (RE 230/90; titer 106.5 TCID50/ml), were used in this study. Manual toothbrushes were disassembled into bristles, bristle fixation, and back of the toothbrush head, contaminated with the viruses and air-dried for 24 h. In a second experiment, whole toothbrush heads were contaminated, rinsed with water (5 ml for 15 s) and then air-dried. Results For FeCoV, immediately after contamination, the following average titers were recovered: fixation: 106.41, back of head: 106.81 and bristles: 106.63 TCID50/ml. Following air-drying of 12 (fixation) and 24 h, titers of ≤ 102.5, 103.75, and 102.72 TCID50/ml were found in the respective groups, with a detection limit of 102.5 TCID50/ml. For H1N1, immediately after contamination, the following average titers could be recovered: fixation: 105.53, back of head: 105.97 and bristles: 105.75 TCID50/ml. Following air-drying of 8 (fixation) and 24 h, titers were ≤ 102.5, 103.63, and 103.53 TCID50/ml in the respective group, again with 102.5 TCID50/ml being the detection limit. In case of water rinse, no infectious virus could be recovered after 12 h. Conclusion Viral load of both viruses is reduced by air-drying, especially following water rinsing. Clinical relevance The toothbrush itself plays an insignificant role in the self-transmission of coronavirus and influenza virus.

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“…Raw saliva has been proven as a reliable source of viral genetic material as viral loads in this fluid can be equivalent to NPS [ 8 , 9 , 10 , 11 ]. Several processing sample alternatives have been reported for the use of saliva as specimen for SARS-CoV-2 infection diagnosis, including direct lysis by heating to avoid the RNA extraction step [ 12 , 13 ] or using commercial reagents [ 10 ], common buffers such as PBS or TE [ 13 ], Proteinase K [ 14 , 15 ], or guanidine hydrochloride [ 16 ] as lysis-inactivating solutions. However, some of these strategies have been reported to inhibit the RT-qPCR reaction to some degree [ 13 , 17 ], showing varying sensitivity for detecting viral targets in saliva.…”

Section: Introductionmentioning

confidence: 99%

Development and Testing of a Low-Cost Inactivation Buffer That Allows for Direct SARS-CoV-2 Detection in Saliva

et al. 2022

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Massive testing is a cornerstone in efforts to effectively track infections and stop COVID-19 transmission, including places with good vaccination coverage. However, SARS-CoV-2 testing by RT-qPCR requires specialized personnel, protection equipment, commercial kits, and dedicated facilities, which represent significant challenges for massive testing in resource-limited settings. It is therefore important to develop testing protocols that are inexpensive, fast, and sufficiently sensitive. Here, we optimized the composition of a buffer (PKTP), containing a protease, a detergent, and an RNase inhibitor, which is compatible with the RT-qPCR chemistry, allowing for direct SARS-CoV-2 detection from saliva without extracting RNA. PKTP is compatible with heat inactivation, reducing the biohazard risk of handling samples. We assessed the PKTP buffer performance in comparison to the RNA-extraction-based protocol of the US Centers for Disease Control and Prevention in saliva samples from 70 COVID-19 patients finding a good sensitivity (85.7% for the N1 and 87.1% for the N2 target) and correlations (R = 0.77, p < 0.001 for N1, and R = 0.78, p < 0.001 for N2). We also propose an auto-collection protocol for saliva samples and a multiplex reaction to minimize the PCR reaction number per patient and further reduce costs and processing time of several samples, while maintaining diagnostic standards in favor of massive testing.

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Saliva is Comparable to Nasopharyngeal Swabs for Molecular Detection of SARS-CoV-2

Abstract: In general, the most accurate COVID-19 testing is hands-on and uncomfortable, requiring trained staff and a “brain-tickling” nasopharyngeal swab. Saliva would be much easier on both fronts, since patients could collect it themselves, and it is after all just spit.

Cited by 35 publications

References 24 publications

Population wide testing pooling strategy for SARS-CoV-2 detection using saliva

Population wide testing pooling strategy for SARS-CoV-2 detection using saliva

The role of toothbrush in the transmission of corona- and influenza viruses — results of an in vitro study

Development and Testing of a Low-Cost Inactivation Buffer That Allows for Direct SARS-CoV-2 Detection in Saliva

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