Co-creator discusses COVID-19 saliva test that can detect virus within hours
INDIANAPOLIS (WISH) — Researchers from Yale School of Public Health developed a new coronavirus test that can detect the virus with a simple, noninvasive saliva swab.
Results, they say, are confirmed in as little as three hours.
News 8 spoke with Chantal Vogels, post-doctoral research fellow and co-creator of “SalivaDirect.” Vogels spoke about how the test was created, the cost effectiveness compared to other tests on the market, and when SalivaDirect should be available to the public.
Below is a transcript of the interview.
Gillis: You and your colleagues developed what’s called SalivaDirect. Tells us a little bit about the test, how it was developed and how does it compare to other COVID-19 tests?
Vogels: We developed SalivaDirect to help increase the testing here in the United States. There’s 3 different ways of testing that we’ve included in SalivaDirect as opposed to many of the other tests that are out there. As the name suggests, we use a sample of saliva to test. This is easier to collect. You can just gently expel saliva into a tube and therefore you don’t have to take one of those very uncomfortable nasopharyngeal swabs and it’s also safer to collect.
And then in sample processing, we simplified the protocol by skipping the normal extraction step. So, the extraction is normally used to break open the virus and get the genetic material of the virus free for infection. What we do is we treat the sample with a simple enzyme and heating step and overall it showed that our test is very comparable to those that do use this extraction step.
Gillis: What is that enzyme in the saliva?
Vogels: The enzyme is just a chemical that we use to break open the virus in the saliva. So, it’s not present in the saliva. We add it to the saliva. We mix it and we heat it and then that sample is ready for testing with PCR (polymerase chain reaction).
Gillis: I understand the test doesn’t require much special equipment. There’s a quick turnaround. Can you talk about that?
Vogels: Yes. So, the test does require some specialized equipment so it can only be run in CLIA-certified labs (The Clinical Laboratory Improvement Amendments). However, what we did is we made the test very flexible. So, instead of having just one kit we have validated reagents and instruments from multiple vendors and by doing so we hope to minimize supply chain issues.
Essentially, if one of these products runs into issues…because the products are commonly available products…they are already out there…supply chain bottlenecks with one of them and there is a flexibility to take one of the other ones we’ve already validated. Overall this is going to be very quick. So, with this flexibility and the simpler protocol we can test about 92 samples within 3 hours.
Gillis: And, on average, how much time and money can SalivaDirect save compared to other tests?
Vogels: If you look at the reagents we used for our tests, depending on which one you pick and depending on which vendor…the costs are between one and four dollars and that is a significant reduction from other tests which can be more expensive. Of course, because it has to be run in a CLIA-certified lab there’s additional costs associated with that, but we hope this test can roll out with a price of about $10.
Gillis: According to Harvard University researchers, there’s a high level of false negatives in terms of nasal swabs, but also saliva tests. About 100% of the time, they say on the day you are exposed to the virus there is going to be a false negative. Forty percent of the time if you’re tested four days after exposure there is going to be a false negative. And then 20% of the time when a person is tested 3 days after developing symptoms there will likely be a false negative. So, I just want to circle back to the reliability and validity of SalivaDirect.
Vogels: So, one of the components in the validation that we did…we’ve now been issued FDA emergency use authorization and one step of the process was to compare results obtained with nasopharyngeal swabs in parallel to saliva. Our New Haven hospital (in Connecticut)…we collected nasopharyngeal swabs and saliva swabs from the same patients. We tested that in parallel and we found a 94% positive agreement. So, 94% of the samples that we tested turned out to be positive.
It’s important to note, however, these nasopharyngeal swabs–which are considered the gold standard–they can be very variable because it’s hard to take the swab correctly and therefore you might also miss if the swab is not taken correctly. You might miss the detection or virus and this depends on which day you test. The amount of the virus in the body changes over time and if there are only a few particles present then there’s a higher chance you might miss it.
So, overall what we see is that we have 3 samples for which the nasopharyngeal swab tested negative, but we were able to detect it in the saliva. I think for both sample types there is something to say. Sometimes you might miss it, but one is not superior to the others.
Gillis: I was reading something from other researchers at Yale University of Public Health and they recommend college students be tested 2 to 3 for the coronoavirus times a week as a preventative measure. Will this help because it’s cost effective and will potentially have wide distribution?
Vogels: Our test is faster and less expensive and that will help to scale it up once it’s made available to the general public. So, with these school reopenings it’s really important that testing is frequent and it really helps if you can increase your capacity in these CLIA labs to run a test that can be run faster and are less dependent on supply chain issues and so overall I definitely think using SalivaDirect will help testing be more available and scalable
Gillis: And when can we expect this to be available to the public?
Vogels: We’re working hard to designate labs to run our tests so we’re in the process right now. We really hope to get this available very soon.
News 8’s medical reporter, Dr. Mary Elizabeth Gillis, D.Ed., is a classically trained medical physiologist and biobehavioral research scientist. She has been a health, medical and science reporter for over 5 years. Her work has appeared in national media outlets. You can follow her on Instagram @reportergillis and on Facebook @DrMaryGillis.