The collection of nasal and throat swab samples to detect the presence or absence of the novel coronavirus SARS-CoV-2 has proven problematic on a few fronts, particularly in the U.S. The swabs themselves often have become scarce and difficult to obtain, while health care workers are routinely risking their own health commonly in the absence of proper protective equipment. In addition, sampling difficulties have largely been blamed for a very high false negative rate that could be as much as 25%.

Instead of relying upon a swab sample, a new saliva test that has received emergency use authorization from the U.S. FDA would instead allow for self-collection at the point of care. This is the first such status granted by the FDA for a saliva-based collection approach. A study has found this approach is equivalent to swab samples. The method was developed by researchers at the Rutgers University Cell and DNA Repository (RUCDR) in partnership with biosampling collection specialist Spectrum Solutions LLC, which is based in Salt Lake City, and clinical laboratory Accurate Diagnostic Laboratories (ADL), which is based in South Plainfield, N.J.

The new method is expected to enable safer, more widespread testing for the novel coronavirus. The originators have already been communicating with the White House COVID-19 testing task force on how to expand testing by engaging distributors to get the collection devices to health care providers and to qualify additional laboratories to conduct the RNA analysis based on this type of sample.

Safer sampling

“It doesn't require a health care worker,” explained Spectrum CEO Stephen Fanning of the saliva collection device to BioWorld. “So, anyone can just be handed it. Right now, with the current swab, the health care worker needs to be there and there's a chance that he or she could become infected.”

“The way in which we preserve the liquid that's in it does a couple things,” he continued. “It basically gets rid of the virus, but it leaves the RNA markers. When those markers get there, it's in a very robust solution so they can tell if, in fact, you have the virus. If the health care worker is opening that tube once it's sent to the lab, there's not any way that worker could be contaminated because the virus is dead in the tube. But what we've been able to keep are the RNA markers in suspension, and that they can again determine if you have it or not.”

Spectrum can currently produce roughly 1 million saliva collection devices a month; the company is in the process of acquiring more injection molding machines and within the next two to three weeks aims to triple or even quadruple that initial capacity.

High-volume testing is a crucial component in plans being developed to more safely reopen the U.S. economy and monitor disease prevalence; some approaches call for large-scale, routine testing, while others remain focused on contact tracing and/or would target specific groups such as health care workers or the most vulnerable such as the elderly or chronic disease patients.

A plan from former FDA commissioner Scott Gottlieb, who is a Resident Fellow at the American Enterprise Institute, a conservative think tank, calls for a minimum U.S. capacity of 750,000 tests per week.

Test validation

The saliva testing method was validated in a study to confirm saliva could be used in place of nasal pharyngeal or oral pharyngeal swabs for detecting COVID-19 in both symptomatic and asymptomatic patients. The testing found 100% concordance in detecting a patient that had the virus between the methods. It remains unclear thus far if the novel saliva approach could improve upon the inconsistencies in the swab-based sample collection process, which have been widely scrutinized.

Known as the SDNA-1000 Saliva Collection Device, it was used in the study with the Thermo Fisher Taqpath SARS-CoV-2 Assay, which already had an emergency use authorization from the FDA for use with a swab sample that dates back to mid-March. It is a multiplex real-time, PCR qualitative test. The Rutgers lab also used Perkin Elmer nucleic acid extraction.

“The preservation solution was a main focus of the study to ensure that the virus would be inactivated to the point that we would be able to maintain and stabilize the RNA transcripts for sensitive and specific QPCR analysis in order to determine whether a person has the virus,” said Andrew Brooks, chief operating officer at RUCDR Infinite Biologics and Professor of Genetics at Rutgers University. “The device’s intuitive ease-of-use to facilitate minimally supervised or in most cases complete self-collection is a tremendous advance to current COVID-19 sample collection strategies. Together, these benefits will significantly add to expanding access to critical testing needs.”

Home-based testing?

In addition to relatively fast results within a few days and vastly reduced exposure for health care workers, the saliva test also opens up the potential for at-home testing. Spectrum has supplied the saliva collection tubes used by Ancestry.com, which is administered at home.

A major at-home collection screening effort is not unprecedented. Cologuard from Madison, Wis.-based Exact Sciences Corp. is a stool-based DNA test for colorectal cancer that is based on a sample collected at home; it has gained widespread adoption and payer reimbursement.

But any home testing for COVID-19 is expected to require an additional go-ahead from the FDA for a direct-to-consumer product and, at least for now, the originators are focused on the enormous challenge of making saliva collection widely available at the point of care.

"Imagine – you pull up, you roll down your window, they give you the collection device, it takes seconds to spit into it. You put the cap on, which releases the preservation solution into the vial," said Rupen Patel, CEO of Accurate Diagnostic Labs. "You wipe it with a disposable alcohol pad, and you hand it back to the person at the window and you go off on your way. Twenty-four to 48 hours later, you get your test results. All this can happen while mitigating exposure and using best efforts to reduce the use of valuable PPE (Personal Protective Equipment)."

LDTs exist

Currently, Vault Health and Microgendx have developed saliva-based lab tests, and they are available to clinics and hospitals, as well as direct to patients via provider authorization. These laboratory developed tests (LDTs) require provider authorization to send the collection cup to the patient and the testing itself is performed in the lab. However, these LDTs cannot be distributed to other labs for any reason unlike tests with an EUA.

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