What is SalivaDirect™?
Regularly testing large numbers of people will play a huge role in monitoring transmission of SARS-CoV-2. Quickly detecting and isolating active cases – people who can transmit the virus, whether symptomatic or asymptomatic – is the cornerstone for limiting disease spread. In addition, accurate data on the number of active cases is necessary to inform policy makers (at local, state, and federal levels) as well as individuals what the short-term risk of spread is and how safe it is to do things like return to workplaces, attend school, and see friends and family.
Ramping up testing for effective SARS-CoV-2 surveillance has faced several barriers. One of those is the reliance on nasopharyngeal swabs, or “NP swabs.” Getting these swabs can be uncomfortable, which discourages people from getting tested frequently. NP swabs also have to be collected by someone who is trained to do so, adding a logistical barrier and putting those performing the test at risk of getting sick. Because SARS-CoV-2 rapidly spread worldwide, it has put immense strain on the supply chains that provide materials for tests, including swabs and test reagents. SalivaDirect™ is a solution to these problems.
SalivaDirect™ is a new method for testing people suspected of SARS-CoV-2 infection.
SalivaDirect™ is unique in 3 ways:
Saliva-based: Saliva Based test will increase testing compliance. This type of test also protects healthcare workers from potential exposure to sick patients and works around worldwide swab shortages.
Extraction-free: Nucleic acid extraction is time-consuming and expensive, and there have been worldwide shortages of the supplies needed to do it. For SalivaDirect™, Yale School of Public Health worked out how to skip this step, making it accessible to more high complexity CLIA certified laboratories like Advaite Inc.
Flexible: While many labs have similar equipment, they may be from a different company, and all of these need to be authorized by the FDA. Yale School of Public Health is aiming to validate their method with as many different variations of equipment and reagents as possible to allow labs to work with what they have and to prevent shortages.
Validation Results
Limit of Detection
A positive saliva specimen from a confirmed COVID-19 patient with a known virus concentration (3.7 × 104 copies/µL) was spiked into saliva collected from health care workers who tested negative for SARS-CoV-2 using the CDC assay.
Spiked saliva specimens were treated with proteinase K, heat inactivated, and tested in the dualplex RT-qPCR assay.
Input volumes, matrices and RT-qPCR programs are the same for each combination of proteinase K, RT-qPCR kit, and RT-qPCR instrument.
The following 2-fold dilutions series of 400, 200, 100, 50, 25, 12, and 6 copies/µL were tested in triplicate to determine the preliminary limit of detections.
The final limit of detection was confirmed with 20 additional replicates.
We used this approach to determine the limit of detection for proteinase K and RT-qPCR kits from 3 different vendors, and 3 RT-qPCR instruments.
Stability
Stability of spiked-in saliva samples used for the limit of detection experiment was determined by placing 3 different concentrations (12, 25, and 50 copies/µL) for 7 days under different temperature regimes (4°C, room temperature, and 30°C). Results were compared to results obtained in the limit of detection experiment (fresh). Samples were treated with ThermoFisher Scientific proteinase K and tested with the ThermoFisher TaqPath RT-qPCR kit on the Bio-Rad CFX96. Overall, samples were stable under each condition for at least 7 days.
Cross-Reactivity
In addition to cross-reactivity tests performed by the CDC, we have tested SalivaDirect™ on 52 saliva specimens collected from adults during the 2018/2019 and 2019/2020 (pre-COVID19) autumn/winter influenza seasons and detected 51 negative, and 1 invalid results.
Clinical Validation:
Performance of SalivaDirect™ was compared to the authorized ThermoFisher Scientific TaqPath RT-PCR COVID-19 kit by testing 37 paired positive and 30 paired negative nasopharyngeal (NP) and saliva samples. Nasopharyngeal swabs and saliva were collected from inpatients and healthcare workers in the Yale-New Haven Hospital. Saliva was collected in sterile urine cups or 5 mL tubes without addition of any preservatives. The ThermoFisher Scientific TaqPath COVID-19 combo kit combines RNA extraction using the MagMax Viral/Pathogen Nucleic Acid Isolation Kit with a multiplex RT-PCR diagnostic assay targeting 3 regions of the SARS-CoV-2 genome (N, S, and ORF1ab). For SalivaDirect™ we used the ThermoFisher Scientific proteinase K, ThermoFisher Scientific TaqPath RT-PCR kit, and Bio-Rad CFX96 instrument.
We selected the positive and negative pairs based on preliminary results of our modified research protocol based on the US CDC primer-probe sets. Out of the 37 nasopharyngeal swabs that were tested with the TaqPath COVID-19 kit, three specimens tested negative (Ct value cut-off of 37). However, earlier results with the modified CDC assay indicated a (weakly) positive signal, and the paired saliva specimen tested positive with both SalivaDirect™ and the TaqPath COVID-19 kit. Two saliva specimens tested negative for SalivaDirect™ while the NP swab and saliva tested positive or inconclusive with the TaqPath COVID-19 kit.
All negative NP and saliva specimens tested negative with both the TaqPath COVID-19 kit and SalivaDirect™.
Important Information about SalivaDirect™
SalivaDirect™has not been FDA cleared or approved. It has been authorized by the FDA under an emergency use authorization for use by authorized laboratories. The test has been authorized only for the detection of nucleic acid from SARS-CoV-2, not for any other viruses or pathogens. This test is only authorized for the duration of the declaration that circumstances exist justifying the authorization of emergency use of in vitro diagnostic tests for detection and/or diagnosis of COVID-19 under Section 564(b)(1) of the Act, 21 U.S.C. § 360bbb-3(b)(1), unless the authorization is terminated or revoked sooner.
Get Saliva Direct™ COVID-19 Test results in 24-48 hours.
How the process works:
4 easy steps:
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- Submit a request for quote
- Once approved, collection supplies shipped to you within 24 hours*
- Ship back the collected samples to the Lab.
- Get the results within 24-48 hours*
Saliva Collection Procedure:
For Collectors: PDF available for download
For Patients: PDF available for download
Test Requisition and Report form: PDF available for download
Schedule a call with our team to discuss about SalivaDirect™ testing for your organization today.
