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As testing delays continue to hamper efforts to quickly identify people infected with the coronavirus, there's a push for cheaper, faster tests. NPR's Allison Aubrey reports on a new saliva test developed by researchers at Yale University who are awaiting emergency use authorization from the Food and Drug Administration.
ALLISON AUBREY, BYLINE: If you've been tested for coronavirus, you may have experienced the sting of a swab being inserted deep into your nasal passages. But there is a less invasive way of testing that involves spitting into a cup or tube. Nathan Grubaugh is an assistant professor of epidemiology and microbial diseases at the Yale School of Public Health. Early in the pandemic, he started comparing saliva samples to the swab samples from patients who were hospitalized with the virus.
NATHAN GRUBAUGH: We were finding - to our surprise, really - more virus in the saliva than we were in the swabs. And also, we could detect it from the same patients more consistently.
AUBREY: The challenge has been to develop a test that won't be subject to supply chain snags and can deliver results faster and cheaper. So what Grubaugh and his colleagues have designed is a streamlined diagnostic test that uses heat to break open the virus.
GRUBAUGH: We get rid of the most cumbersome stuff, which is extracting the nucleic acids. And we replace that with something that's really simple. You add an enzyme, you heat it up, so you lose the most expensive step and the most time consuming and the most skilled.
AUBREY: Grubaugh says this cuts down on the labor costs. And with people taking their own saliva samples, it could reduce the cost to the health care system to collect the samples. He estimates it will cost somewhere between $1 and $4, plus labor, to do a test. And with emergency use authorization from the FDA, commercial labs could license the Yale test.
GRUBAUGH: We are not a manufacturer. Essentially, all we're doing is training the recipe. What people have to do is follow that recipe.
AUBREY: A very similar saliva test is already being used on the campus of University of Illinois at Urbana-Champaign. All returning students will be given two tests per week. And the university's Martin Burke, a professor of chemistry who helped design the test, says they're able to give results quickly.
MARTIN BURKE: Yep. So our average is about three to six hours, which is critical. So fast and frequent - that's absolutely the key. You know, if you don't get your results back for one or two days, beyond that, it's pretty much useless in terms of being able to mitigate the spread. And so in contrast, if you get your results back in hours, you can quickly isolate individuals - right? - who are tested positive.
AUBREY: Even if tests are not 100% sensitive at detecting virus, they tend to catch people at their most infectious. So if you test someone on a Monday who's just been infected and they're negative, you're likely to get a positive result if you test again on Thursday.
BURKE: So by testing frequently, the chances of catching that person when their viral load goes up is very high. And so if you run the numbers - let's say you had a test that was only 85% sensitive. If you do that twice a week, you're going to catch 99% of the people - 98% of the people.
AUBREY: Burke says that's why frequent testing makes sense. And saliva tests may make it easier to do this. A French company has already started to sell a saliva test in Europe that can be analyzed on site using a portable kit and give results within an hour. More tests like this are likely on the way. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.
