Published on May 27, 2020

  • A new test for COVID-19 involves spitting into a tube, instead of swabbing the nose.
  • The process for collecting saliva is similar to at-home DNA tests and results are usually available within 24 to 72 hours.
  • The saliva test is used to diagnose a current COVID-19 infection, not check for antibodies against it.
  • You can get the COVID-19 saliva test at your doctor's office or by calling a telehealth doctor for an at-home test kit authorization form.

Video Transcript


JOHN WHYTE: You're watching Coronavirus in Context. I'm Dr. John Whyte, chief medical officer at WebMD. Today, we're going to spend a few minutes talking about a new test for coronavirus. It's a saliva test. And I'm joined by Dr. Andrew Brooks. He is professor of genetics at Rutgers. Dr. Brooks, thanks for joining me.

ANDREW BROOKS: My pleasure.

JOHN WHYTE: Let's start and explain to our audience. How does this test work?

ANDREW BROOKS: So the collection of the sample is different than what we've traditionally heard about and what we started with in the beginning of molecular testing for coronavirus. The use of saliva, um, makes collection more robust, more simple. You spit into a tube, up to a line that's on the tube. You screw the cap on, which has a preservation agent, which drops down into the saliva and preserves it.

When the sample gets to the lab, the test is really no different than what we've been doing for swabbed-based analyses, where we extract nucleic acid. We do qPCR to look for the presence of viral genes in the sample.

JOHN WHYTE: So you're using the same technology as they used on the swab, in terms of PCR. Is that right?

ANDREW BROOKS: Similar to-- a very similar detection technology and molecular process. What's different is the biomaterial and how we collect it.

JOHN WHYTE: Mm-hmm. And the collection, though, is similar for our viewers, as they might do for some of the, um, in-home DNA kits. Is that right, in terms of spitting?

ANDREW BROOKS: In fact, it's-- it's very similar to the point when we started at the first drive-through in New Jersey. And I was there. A few of the people that were coming up to be tested were handed the device. And they said, no, I already know where I come from. I've done I'm here because I think I'm sick. All right, so, um, it is-- it is very much similar in the process of collection, yes.

JOHN WHYTE: And this is not antibody testing. This is a diagnostic test for coronavirus, COVID-19. Correct?

ANDREW BROOKS: C-- correct.

JOHN WHYTE: And we've been talking a lot over the last few weeks about sensitivity and specificity, positive predictive value, negative predictive value, recognizing we're not trying to give a biostatistics lesson to our audience. But can you help explain and to talk a little bit about the accuracy of this type of test?

ANDREW BROOKS: So the accuracy of-- of qPCR and molecular detection is very high. At the outset, you want to make sure that the design of the probes and primers that you're using are specific to what you want to detect, so you know that the specificity is for the virus or the transcript or whatever you're looking for.

And-- and all of the tests out there have a very high level of specificity. It's-- it's not like an antibody test, where there may be cross reactivity to proteins and similar organisms. So the specificity is-- is-- is direct.

JOHN WHYTE: The specificity, if it's very high, it's also going to allow us to rule in a disease, if it's positive. Correct?

ANDREW BROOKS: Correct. Um, but also to keep in mind, that all of the emergency use authorizations are for presumptive diagnoses. Um, and all negative tests from any sample source should be tested from a different sample source when clinically indicated. And that's part of every emergency use authorization.

JOHN WHYTE: Good point.

ANDREW BROOKS: So it's really important-- it's really important that people know that, if they're symptomatic and they're COVID-19 by any molecular test, including saliva, and their symptoms increase and under the care of the physician, or change, that needs to be confirmed. Because it's not a true confirmatory results. And the same thing with positive, it's a presumptive diagnostic.

You know, we're in very different times right now with the FDA and these emergency use authorizations. So people really need to understand the process.

JOHN WHYTE: And you were going to talk about it's sensitivity. So it's highly specific how sensitive it is.

ANDREW BROOKS: Right. So-- so s-- sensitivity takes into consideration a number of things with respect to COVID molecular testing, in my opinion. Sensitivity is determined by the number of copies you can detect per amount of material that you have it in.

And-- and all of the FDA authorizations are based on determining the level of detection, the upper and the lower level of detection. And that's done by spiking in viral transcripts into the matrix that you're testing-- in this instance, saliva-- carrying it through the process, and seeing what you can detect. So really, understanding whether or not the saliva matrix is different than the universal transfer media or the viral transfer media presence is what gets at the absolute sensitivity of the test.

Our sensitivity is approved for down to 200 copies of the viral transcript in one mL of-- of media.


ANDREW BROOKS: Now, h-- how does that translate into false negatives and performance--


ANDREW BROOKS: --um, uh, you know, for patients? Uh, that's a little bit different. Because what that number doesn't take into consideration is the variability associated with sample collection. So whether you're self swabbing [INAUDIBLE] or-- or you're going for a very uncomfortable nasopharyngeal swab or just spitting into a tube, there could be different impacts on the robustness of collection, which really translate into false negatives and could negatively impact that-- that sensitivity measure we were just talking about.

JOHN WHYTE: Is the test currently available?

ANDREW BROOKS: The test is currently available, yes.

JOHN WHYTE: And where would, uh, people go to-- to get that test?

ANDREW BROOKS: So, um, primarily, if you go through your healthcare providers--


ANDREW BROOKS: --you can identify what tests they are offering and where they get them from. So we have partnerships, um, with, uh, different health care providers. And most of those are for, uh, physician-ordered, physician-guided, um, a collection or a supervised collection.


ANDREW BROOKS: If-- if you're looking for a home collection, which we were approved a week ago from the FDA, then you need to, uh, find a telehealth partner that-- that provides those tests.


ANDREW BROOKS: Because it's important to point out that at-home collection does not imply home testing. It does not imply self-testing.


ANDREW BROOKS: It's important to point out that the test still has to be ordered by licensed physician in your state. There still has to be the proper identification of the right person in the right test--

JOHN WHYTE: Mm-hmm. ANDREW BROOKS: --or device that you're using. And the test, then, needs to follow all the EUA authorizations. So, um, there are three partners, uh, currently, uh, supporting our test. Uh, there's Vault Health, um, Vitagene or IO Health and ixlayer.

Um, we have vetted and approved their process to ensure that home collection is being done the way the EUA authorizes.

JOHN WHYTE: And test results come back in about 48 hours. Is that correct?

ANDREW BROOKS: Once they get the lab, our turnaround time is approximately 48 hours. Um, it can be as soon as 24. It can be as late as-- as 72, if a retest is required. But, uh, 48's a pretty reliable number.

JOHN WHYTE: Well, this is one more tool in our tool box, uh, for testing. Is it going to change the testing paradigm?

ANDREW BROOKS: I think what it does is it makes testing more available. Um, there are no tests currently approved for, um, truly asymptomatic, uh, individuals. Uh, we're collaborating with the FDA and with others to-- to try and get to that point. Um, and-- and once the FDA is comfortable with respect to the incidents or understanding the incidents and how that impacts sensitivity, then saliva will really change the landscape quite a bit. You know?

For the immediate past, it's been about getting patients to the test. Now, we can get the test to the patient, which will drastically impact the number of tests that can be done, a larger screening, um, as well as being able to help not just patients that are sick. But, ultimately, once asymptomatic testing is more commonplace, uh, companies and other organizations allowing to screen and protect employees and people that are participating in everyday events, um, so that we can get back to what we remember our world being.

JOHN WHYTE: Well, Dr. Brooks, I want to thank you for taking the time to speak with us today.

ANDREW BROOKS: My pleasure. JOHN WHYTE: And I want to thank you for watching Coronavirus in Context. I'm Dr. John Whyte.