
Saliva-based Covid-19 test approved by FDA - jakozaur
https://news.yale.edu/2020/08/15/yales-rapid-covid-19-saliva-test-receives-fda-emergency-use-authorization
======
vikramkr
This is an emergency use authorization, not a full approval by the FDA, and
this only lasts until the state of emergency ends or the test is actually
approved/rejected by the FDA. Either way, this is some exciting news as it
could make sample collection easier for testing. It doesn't look like it
overcomes the qPCR reagent bottlenecks to actually analyze the samples though,
so I wonder what the full impact on testing will actually be.

~~~
analog31
So far as I know, all covid tests in use right now are being produced under
emergency authorization.

~~~
vikramkr
And that's come with a lot of problems as we saw with the antibody testing
fiasco with all the nonfunctional tests. So the precedent suggests cautious
optimism, emphasis on the cautious.

~~~
skosuri
Actually, emphasis on the optimism. The Yale work is really well done.
Sensitivity is a little low, but people keep ignoring cost, scalability,
frequency and ease. This is what is needed for back to work/school
applications and the first test that actually satisfies these criteria imo.

~~~
vikramkr
Absolutely really good work. My concern is still that it doesn't seem to solve
the qpcr bottleneck. Its great that it gets rid of ena extraction (as someone
trying to get enough reagents to do any sort of real work in my lab - I'm all
too aware of how much trouble they're saving themselves by cutting out that
bit). The pcr part doesn't seem to be addressed though - amd if it isn't
(without something like pooling or using something like LAMP) this will just
add to the backlog of tests.

On the other hand, will still def second you on the quality of the work. It's
some really solid science.

------
lettergram
Kinda weird... I know University of Illinois has been doing saliva-based
testing[1] for a few weeks now[2].

They also plan to roll it out nationally [3].

I am curious if this is the same test? I know students at UIUC need to do two
tests a week and many have been.

Test results come back in a couple hours from what I’ve seen.

[1] [https://illinoisnewsroom.org/university-of-illinois-
creates-...](https://illinoisnewsroom.org/university-of-illinois-creates-
saliva-covid-19-test-with-a-plan-to-use-it-on-thousands-of-students-this-
fall/)

[2] [https://wgntv.com/news/coronavirus/university-of-illinois-
ro...](https://wgntv.com/news/coronavirus/university-of-illinois-rolls-out-
coronavirus-saliva-test/)

[3] [https://dailyillini.com/news/2020/08/10/university-
covid-19-...](https://dailyillini.com/news/2020/08/10/university-
covid-19-saliva-testing-expands-nationally/)

~~~
skosuri
They both work very similar in theory: unpurified saliva with qPCR. Though as
far as I know U of I doesn't have their EUA and have not stated they applied.

------
chmaynard
On Aug. 14, 2020, Science Friday featured a discussion about rapid testing
strategies with two scientists. The recording is well worth a listen. The key
take-away is that while PCR tells you if you're infected, to protect others
what you really want to know is if you're infectious.

[https://www.sciencefriday.com/segments/covid-testing-
strateg...](https://www.sciencefriday.com/segments/covid-testing-strategy/)

~~~
comicjk
A correct positive PCR doesn't even guarantee infection - it just tells you
that you have been infected within the last month or so. Old, inactivated
viral RNA can still trigger a positive weeks later.

~~~
ejstronge
Are there examples of studies on people testing positive months later? qPCR is
used in many settings for medical testing and the guidelines for other
diseases are that residual bacterial RNA is cleared 7-14 days after successful
antibiotic treatment. Obviously, COVID is caused by a virus, but a much longer
period to clear viral RNA is not intuitive.

~~~
_Gyan_
> Are there examples of studies on people testing positive months later?

Yes. However, it appears to not be live virus.

[https://www.medrxiv.org/content/10.1101/2020.07.21.20125138v...](https://www.medrxiv.org/content/10.1101/2020.07.21.20125138v1)

------
rtlfe
Are there meaningful differences between this and the Rutgers saliva test that
received emergency use authorization in April?

[https://www.rutgers.edu/news/new-rutgers-saliva-test-
coronav...](https://www.rutgers.edu/news/new-rutgers-saliva-test-coronavirus-
gets-fda-approval)

~~~
sna1l
It sounds like the main difference is that this saliva test doesn't require
specific equipment and can be done by labs everywhere.

Also about 10 times as cheap!

Source: [https://www.espn.com/nba/story/_/id/29667299/fda-allowing-
sa...](https://www.espn.com/nba/story/_/id/29667299/fda-allowing-saliva-based-
test-funded-nba)

~~~
vikramkr
It still requires specific equipment- it looks like its still a qPCR based
test, not an isothermal amplification type test, so it needs a qPCR machine
and reagents. It cuts out one step, RNA extraction, which means it trades off
some sensitivity for a faster and cheaper result.

------
eganist
> Saliva-based Covid-19 test approved by FDA

Editorialized title. Title from the article is actually

> Quick and affordable saliva-based COVID-19 test developed by Yale scientists
> receives FDA Emergency Use Authorization

------
yashap
Pretty curious to know what the false negative rate is. With the most popular
current test (nasopharyngeal RT-PCR), the false negative rate is very roughly
30%, which is already pretty awful. And if you get tested significantly before
or after peak viral load, it’s way worse than 30% [1]. If you get a negative
result, you can’t really trust it, it’s giving false confidence to literally
millions that they don’t have COVID, when they do.

It sounds like this test is not quite as good? If it has, say, a 40-50% false
negative rate, I don’t really care how cheap and fast it is, that sucks. These
tests are all pretty useless if you’re pre-symptomatic, so they’re not good
for screening anyways, and if I’m at peak symptoms, I want accuracy over
speed. I took a nasopharyngeal RT-PCR test and got results the same day,
that’s fast enough if it’s more accurate. But if the accuracy is equivalent,
or very nearly so, then it’s quite interesting.

[1]
[https://www.acpjournals.org/doi/10.7326/M20-1495#s1-M201495](https://www.acpjournals.org/doi/10.7326/M20-1495#s1-M201495)

~~~
mmastrac
This is interesting. I recently had a throat swab test after a week of extreme
fatigue, but at no time did they indicate that the negative result was
anything but certain. I had imagined _some_ false negative rate, but not this
high.

~~~
latchkey
This is why I laugh when people quote the infection numbers. It is potentially
up to 30% wrong or heck, even more... nobody knows... but there is also other
reasons, like inaccurate deduplication when people get multiple rounds of
tests because of the high false negative rate.

Oh and because it is false negative, it is worse than you think, not better.

------
leephillips
The preliminary study shows very high specificity, which is good for something
that may be widely deployed, as it avoids the problem of massive numbers of
false positives: [https://lee-phillips.org/testingbad/](https://lee-
phillips.org/testingbad/)

------
mchusma
I'd like to see the FDA move away from approvals like this and just focus on
lightweight approvals that "the test seems not fraudulent for presenting the
false positive rate and false negative rates of the test, and it is indeed
better than ransom".

Tests should not return "positive" or "negative", rather something like "3 in
4 chance of infection" of positive and "1 in 200 chance of infection" if
negative (something like that). This is both more true and helps people
understand statistics/how these tests work, instead of hiding it.

I don't see a safety risk for a test if it has some predictive value unless it
is fraud.

There could be a separate threshold for "reimbursability" for insurance
reasons.

------
UncleOxidant
"The related research was funded by the NBA, National Basketball Players
Association"

------
ementi
ASU also did something similar

[https://asunow.asu.edu/20200526-discoveries-arizona-state-
un...](https://asunow.asu.edu/20200526-discoveries-arizona-state-university-
develops-saliva-based-covid-19-test)

------
pama
Here is the preprint for this test:
[https://www.medrxiv.org/content/10.1101/2020.08.03.20167791v...](https://www.medrxiv.org/content/10.1101/2020.08.03.20167791v1)

------
gregcoombe
You can get a saliva test today, it's just a bit expensive:
[https://www.vaulthealth.com/covid](https://www.vaulthealth.com/covid)

We did this this morning, and it was not bad. They ship the tubes to your
house, and you get in a Zoom call to verify ID and do the procedure. They
haven't worked out all the kinks (it took much too long to do all of us) but
it was pretty convenient. The biggest issue? It's surprisingly hard to fill up
an entire test tube with spit.

------
vmurthy
From the article, it isn't clear how long it will take to get the results. Is
it the same as the "traditional" test? Any ideas? Here in Oz, I received a
negative in 24 hours (actually more like 14 ) using the nasopharyngeal method
and which was free for me (covered by Medicare) so would love to know if the
turnaround time for SalivaDirect will be lesser as well.

------
perl4ever
I previously read about this in the context of a company that claims they are
working on a similar test:

[https://seekingalpha.com/news/3604178-hindenburg-research-
sk...](https://seekingalpha.com/news/3604178-hindenburg-research-skeptic-of-
sorrentos-covid-spit-test)

------
schoolornot
I'm unfamiliar with "pooled testing". I've read many universities plan on
doing it with a saliva test. Is this something that's been done in the past?
Frankly, it doesn't quite right to me but then again I'm not a scientist.

~~~
ulfw
That‘s how China is able to test millions of people in a short amount of time.
It works only when you have low rate of infections. Instead of testing each
sample you test e.g. 5. If this pooled sample tests positive, you test each 5
individually again (for a total of 6 tests instead of 5). If the pool tests
negative you‘re done and you‘ve only run 1 test instead of 5 individual ones.

So you can run the math yourself to see what % of infection rates it makes
sense to pool and when not ;)

------
Symmetry
There was a recent This Week In Virology covering the importance of tests like
this:

[https://www.microbe.tv/twiv/twiv-640/](https://www.microbe.tv/twiv/twiv-640/)

------
AnimalMuppet
Good. That nose test is _painful_.

~~~
kyriakos
Is it? I heard from people who took it that it looks more unpleasant than it
really is.

~~~
AnimalMuppet
For me, it was quite painful. They stuck a swab to the back of my nose, which
was uncomfortable. They they went several inches further to a place that I
didn't even know I _had_. (I suspect it was the lower sinus cavity, but I'm
not sure.) They jabbed it into the back of that, hard, which hurt. They left
it there, pressed in hard, for 10 to 15 seconds.

On the upside, it felt like that sinus drained a bit after they pulled the
probe out. It may have hurt me more because my sinuses are, um, fuller than
they should be.

------
brian_herman
My tired mind read this as Salvia-based Covid-19 test approved by FDA. That
would be some trip.

~~~
non-entity
lmao this is how I initially read it. I was rather confused for a second.

------
acd
Great news, Building on this idea. Is it also possible to calibrate an
electric tongue to detect COVID-19 from a breath test? COVID-19 has a very
specific smell I think. Breath and saliva test would be quicker than PCR and
would probably be important to protect the elderly as many who have COVID is
asymptotic.

