At the start of the pandemic, University of Illinois researchers developed a saliva-based COVID test.
“They realized early on that if we were going to reopen the university, we would need a test that could be done quickly, cheaply, and that people wouldn't mind repeating over and over and over again,” says Rebecca Lee Smith, an epidemiologist at the University of Illinois, who designed the studies that earned the Illinois test its emergency use authorization. “It's easier if you're going to do it frequently, to do drooling rather than having something stuck up your nose.”
Saliva COVID tests, aka spit tests, are ideal tests for schools looking to conduct regular monitoring of students or other populations and launch Test to Stay policies, say public health experts who have studied the tests. Saliva tests can also serve as a complement to other tests such as rapid antigen ones.
The top saliva COVID tests are relatively inexpensive, highly accurate, and can be fast as results are generally available within a matter of hours. These tests are also easy to administer, especially for kids, and are already in use at many schools and universities across the country.
Where are saliva tests being used?
A separate spit test, the SalivaDirect test, was developed at the Yale School of Public Health by a team led by Anne Wyllie, an associate research scientist in epidemiology, and Nathan Grubaugh, a professor. The SalivaDirect test has been utilized by the University of Ohio and in 15 school districts in Colorado, reaching more than 275,000 students. The tests have also been used successfully by the NBA.
Since getting test results back quickly is vital, the SalivaDirect team advises schools to work with local labs that are within an hour drive so samples don’t have to be shipped. The team has also put together a playbook for labs and schools to collaborate. The tests are currently available at 140 labs in 39 states, which has helped for quick results.
“There are so many labs that are getting results back to their schools or sports leagues within four hours, six hours, eight hours -- a lot within 12 hours,” Wyllie says.
The University of Illinois’ COVID shield saliva test was serving 1,732 K-12 schools and 877,720 students in Illinois in early September; it is being used by schools in Baltimore, Washington D.C., and elsewhere.
It is also used by the University of Illinois to screen unvaccinated students who are required to test every other day. The campus has multiple sites and offers an app that will notify students instantly of the results, which are guaranteed to come back within two days but generally come back much sooner. “It’s averaging seven hours to a result now,” Smith says.
How accurate are saliva tests?
While the quality of saliva tests offered from private companies can vary, the SalivaDirect and COVID Shield tests are highly accurate and comparable to other highly sensitive PCR tests. In fact, these methods can even be better at detecting the virus before someone is contagious.
“We can find cases earlier in the infectious process, that's very important for surveillance screening,” Smith says.
How much do saliva tests cost?
Saliva tests are generally less expensive than nasal tests because each one requires fewer materials, such as swabs and preservatives, and can be processed using more common lab equipment and reagents. The COVID shield tests cost $20 to $30 per test, including sample collection and delivery to the lab.
The SalivaDirect test base price ranges between $1 and $5 depending on supply chains and bulk discount pricing. Labs will often charge $15 to $25 for the tests, though some charge more.
On the other hand, nasal PCR tests often have a $9 to $15 base price and patients can be charged more than $100 for the tests at pharmacies and doctors’ offices.
What should school leaders interested in saliva tests do?
More information about the University of Illinois saliva test can be found on the Shield Illinois website. SalivaDirect’s playbook for schools details how to find funding and provides other advice for surveillance testing.
In addition to working with local labs to reduce shipping times for tests, Wyllie says district leaders can learn from others who have launched successful testing programs. “There's a bunch of school leaders and school districts who have really figured out how to do this, and they are very willing and open to share what they've learned,” she says. “There are a lot of resources in place. So it doesn't necessarily need to be seen as a heavy lift.”
