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Covid-19 Saliva Test Earns FDA Emergency Clearance

SARS-Cov-2 viruses

Scanning electron microscope image showing SARS-CoV-2 viruses, in yellow. (NIAID, NIH)

12 Nov. 2020. A test to detect Covid-19 viruses in saliva rather than nasal swabs received emergency authorization from Food and Drug Administration. The test, developed by medical diagnostics company Wren Laboratories in Branford, Connecticut, can be administered at home, but still requires sending the sample to the company for analysis.

FDA’s emergency use authorization covers the Wren Laboratories Covid-19 PCR test with samples collected from oral and nasal swabs in health care settings, as well as saliva samples taken at a clinic or at home. The PCR test analyzes samples with the RT-PCR technique, the so-called gold standard for detecting the SARS-CoV-2 virus responsible for Covid-19 infections. RT-PCR stands for reverse transcription – polymerase chain reaction, a type of genetic analysis, in this case for the viral RNA signature indicating SARS-CoV-2 in respiratory fluid samples.

Those samples are most often taken with nasopharyngeal swabs inserted through the nose to the back of the throat, which requires trained clinicians. Allowing mid-nose or saliva samples taken at a clinic or at home can relieve valuable clinicians for more important tasks, as well as make sample collection easier for individuals. Wren Labs says the saliva test takes one to two minutes to collect the sample, with results returned within 24 hours after receiving the test kit. The company says its saliva test results exceed 99 percent accuracy with standard RT-PCR tests.

An emergency use authorization by FDA clears previously unapproved drugs or medical devices for use in medical emergencies, and is not a substitute for full authorization. FDA authorizes Wren Labs to collect 0.5 milliliters, about a teaspoon, of saliva from an individual in sample tubes provided by company, either supervised by a health care provider or unsupervised. The sample is then mixed with a stabilizing buffer solution.

The sample tubes are labeled, sealed, and returned in padded biohazard bag and cardboard box, inside a prepaid FedEx envelope. So far, only Wren Labs’ facilities in Branford are authorized to analyze the samples and report back the results. FDA also required Wren Labs to prepare detailed written instructions and fact sheets for patients and health care providers. And the company provides videos about the test on its web site. The list price for the test is $150.00.

Wren Labs also offers a passporting service that transmits testing status and results to a smartphone app. The service can be used by individuals, but appears to be designed for employers, educational institutions, and sports teams that have higher volumes and need repeated tests over time.

Irvin Modlin, emeritus professor at Yale University medical school and consultant to Wren Laboratories, says in a company statement that “Wren can contribute to the global fight against Covid-19 with this ground-breaking new saliva-based PCR test, which combines the highest levels of accuracy with a device which is not only simple to use in a workplace, school, or home but easy to transport without the need for any dry ice or refrigeration.”

Wren Labs’ main business, at least before Covid-19 testing, is a liquid biopsy blood test for cancer called the NETest that provides data on tumor activity. The NETest analyzes blood samples for genetic markers indicating the nature of the tumor and extent of progression. That test is based on Modlin’s research on neuroendocrine tumor disease.

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