Saliva Testing Offers Easier and Earlier Detection of COVID-19

The patient tilts back her head and winces as the long swab stick pushes six inches up her nose. The tip twirls around uncomfortably before it's withdrawn.

"Our saliva test can detect the virus in asymptomatic and pre-symptomatic cases."

A gloved and gowned healthcare worker wearing a face shield and mask tells the patient that she will learn whether she is positive for COVID-19 as soon as the lab can process her test.

This is the typical unpleasant scenario for getting a coronavirus test. But times are rapidly changing: Today, for the first time, the U.S. Food and Drug Administration cleared one company to sell saliva collection kits for individuals to use at home.

Scientists at the startup venture, RUCDR Infinite Biologics at Rutgers University in New Jersey, say that saliva testing offers an easier, more useful alternative to the standard nasal swab.

"Our saliva test can detect the virus in asymptomatic and pre-symptomatic cases," said Dr. Andrew Brooks, chief operating officer at RUCDR.

Another venture, Darwin BioSciences in Colorado, has separately developed an innovative method of testing saliva for the coronavirus that causes COVID-19.

Saliva testing can allow earlier detection to identify people who may not know they are contagious, say scientists at both companies. In addition, because patients spit into a tube or cup, saliva testing is safer for healthcare workers than taking swabs. This frees up scarce personal protective equipment (PPE) for use elsewhere. Nasal swabs themselves have been in scarce supply.

Saliva testing, if it becomes widespread, potentially could mean opening society sooner. The more ubiquitous testing becomes across the population, experts say, the more feasible it becomes for public health officials to trace and isolate contacts, especially of asymptomatic cases. Testing early and often will be essential to containing emerging hot spots before a vast outbreak can take root.

Darwin Biosceiences is preparing to seek an FDA Emergency Use Authorization (EUA) this month for its patented "CoVScreen" testing system, which potentially could be available to labs nationally by mid-summer.

Meanwhile, Infinite Biologics will now begin selling kits to consumers for home collection, upon order by a physician. The FDA said that the company's saliva test was as accurate as the nasal swab method used by health care professionals. An FDA summary documenting the company's data reported: "There was 100% positive and negative agreement between the results obtained from testing of saliva and those obtained from nasopharyngeal and oropharyngeal swabs."

The greatest scientific advantage, said Dr. Brooks, is that nasal and oral swabs only collect the surface area where the swab goes, which may not be the place with most viral load. In contrast, the virus occurs throughout a saliva sample, so the test is more trustworthy.

The lab at Rutgers can process 20,000 tests a day, with a 48-hour turnaround. They have 75,000 tests ready to ship now.

The Leap: Detecting Sickness Before You Feel It

"We wanted to create a device that could detect infections before symptoms appeared," explained Nicholas Meyerson, co-founder and CEO of Darwin.

For more than 300 years, he said, "the thermometer was the gold standard for detecting disease because we thought the first sign of illness was a fever. This COVID-19 pandemic has proven that not all pathogens cause a fever. You can be highly contagious without knowing it."

"The question is whether we can scale up fast enough to meet the need. I believe saliva testing can help."

Therefore, Meyerson and co-founder Sara Sawyer from the University of Colorado began to identify RNA biomarkers that can sense when a pathogen first enters a molecule and "sets off alarms." They focused on the nucleic acids concentrated in saliva as the best and easiest place to collect samples for testing.

"The isothermal reaction in saliva takes place at body or room temperature," he said, "so there's no need for complicated testing machinery. The chemical reaction can be read out on a paper strip, like a pregnancy test -- two stripes if you're sick, and one stripe if you're okay."

Before the pandemic, limited but successful human trials were already underway at CU in Boulder and at the CU Anschutz Medical Campus east of Denver. "This was our proof of concept," he said.

Darwin was founded in March and has secured enough venture capital to concentrate protype development on detecting the virus causing COVID-19. So far, said Meyerson, "Everything works."

A small double-blind test of 30 samples at CU produced 100 percent accuracy. "I'm not sure if that will hold true as we go into clinical trials," he said, "but I'm confident we will satisfy all the requirements for at least 95 percent clinical validation."

The specific "CoVStick" test strips will roll out soon, he said: "We hope before the second wave of the pandemic hits."

The broader saliva test-strip product from Darwin, "SickStick," is still one to two years away from deployment by the military and introduction into the consumer drugstore market for home use, said Meyerson. It will affordably and quickly detect a range of viral and bacterial infections.

A Potential Game Changer

Society needs widespread testing daily, said George Church, founding core faculty of the Wyss Institute for Biologically Inspired Engineering at Harvard University. Speaking at an online SynBioBeta webinar in April, he urged developing stockpiles of testing kits for home use.

As for any potential of false positives, Church said a much bigger risk is not having enough tests.

"Saliva testing is going to speed up the timeline for opening society a lot," said Meyerson. "People need to self-collect samples at home. A lot more people are going to be willing to spit into a tube than to push a swab six inches up their own nose."

Brooks, of Rutgers, addressed the big picture. "It's critical that we open society as soon as possible to minimize the economic impact of the pandemic. Testing is the surest and safest path. The question is whether we can scale up fast enough to meet the need. I believe saliva testing can help."