C19 Notes

Saliva testing easier than clinician-collected nasopharyngeal swab specimens

Author Topic: Saliva testing easier than clinician-collected nasopharyngeal swab specimens  (Read 836 times)

stog

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Saliva testing easier than clinician-collected nasopharyngeal swab specimens

edit 14 may -- most up to date info on this s is probably this interview from May 4th https://dot.la/coronavirus-rapid-test-curative-los-angeles-2645906983.html

Quote
Oral fluids is the technical term, which is slightly different from saliva. Our protocol involves having the person cough first, which releases virus from the upper and lower respiratory tract. Some of that is then caught in the saliva, and also viruses in the saliva. The idea is you're effectively sampling multiple sites at once, which we think gives a slight increase in the sensitivity of the testing.


Curative, offered to supply 50,000 saliva tests a week immediately, with the potential to increase this to 50,000 tests a day. On the day of the offer, 4 April, the UK had capacity to do just 15,499 tests a day and was only testing 8,651 people a day far lower than other European nations such as Germany.
 (these 2 minute do-at-home Saliva tests are much less invasive than the nasopharyngeal (back of the throat) swabs we are using here and give confirmation without supervision)

https://www.theguardian.com/world/2020/apr/29/uk-turned-down-offer-of-10000-coronavirus-tests-a-day-four-weeks-ago

===


https://www.genomeweb.com/pcr/curative-korvalabs-partner-create-high-throughput-covid-19-oral-fluid-testing-lab

Curative, KorvaLabs Partner to Create High-Throughput COVID-19 Oral Fluid Testing Lab

article gives more info

==

which made me comment

for us, as Practitioners who need to get close with Patients, and for which this present situation leaves us no guarantee of bio-security for either us or our Patients in a treatment situation, the potential of affordable saliva tests may allow a return to work at some point; where the Practitioner takes a test each day of work, and each Patient takes the same for each visit.

Accuracy, availability and price will all need to be aligned however.

We both have set ourselves as non-practicing for the foreseeable future, though we still are giving advice on the phone when requested, without making a definitive diagnosis.

Our Patient info is here

http://www.soul-trade.com/clinic/clinic/C19.html



some more links here

this from 10 days ago, and includes a link to a detailed pdf from the Food and Drug Administration (FDA) issuing an Emergency Use Authorization (EUA) for emergency use of the product,

https://www.airforcemag.com/saliva-based-covid-19-testing-coming-to-usaf/

pdf fact sheets on saliva tests for Patients

pdf fact sheets on saliva testing for Practitioners, Healthcare providers


==

however THIS

"A negative test result for this test means that SARS- CoV-2 RNA was not present in the specimen above the limit of detection. However, a negative result does not rule out COVID-19 and should not be used as the sole basis for treatment or patient management decisions. A negative result does not exclude the possibility of COVID-19.



both types of testing 'work' -- though we don't know their % accuracy as yet.

(the throat swabs tests have, last I saw, a 70% accuracy
(compared to a probable Physician diagnosis of known symptoms of maybe 90% accuracy)

Known Symptoms diagnosis will give probably a more accurate result than a positive test, but then there is little need for the test except for data suredness.

However the big gain is the ability to test asymptomatic people.


===



The proviso "negative does not mean there is not C19 present" is perhaps from the FDA Emergency License (EUA April 16th) which requires them to comply with many conditions including

 "No advertising or promotional descriptive printed matter relating to the use of your product may represent or suggest that this test is safe or effective for the detection of SARS-CoV-2."

the throat swabs tests have, last I saw, a 70% accuracy
(compared to a probable Physician diagnosis of known symptoms of maybe 90% accuracy)

Again the benefits of easy saliva testing is that asymptomatic folk can show that they are +- 70% sure they have or do not have C19 at the time of testing.

EUA License https://www.korvalabs.com/wp-content/uploads/2020/04/EUA-CKorva-CoV-letter-of-Authorization.pdf

« Last Edit: May 14, 2020, 12:09:46 PM by stog »

stog

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following a request for some more data on the saliva tests (which may be suitable for ascertaining infectious people presenting for treatment) I found what must be the original info submitted to obtain the EUA emergency licence

as the requirement of the licence is to collate more info as it is used there should be bigger data trials available soon as it is being used by City of LA and the USAF

re original data they perhaps submitted for EUA i found this pdf https://www.fda.gov/media/137089/download found  via COVID-19-Science-Report-Diagnostics-11-May.pdf attached (p36,37 & 77) ]showing 100% sensitivity & specificity

attached both pdfs here
« Last Edit: May 14, 2020, 09:50:20 AM by stog »

stog

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the problem with the data above I am told is that it is simply comparing swab with nasal efficacy, but we still don't have detail on details on sensitivity and specificity of the test or the viral load threshold from which the test becomes positive.

If anyone sees any data please let me know, and hopefully more info should soon appear if it is being used by City of LA
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stog

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just googling and found https://www.nbclosangeles.com/news/coronavirus/new-at-home-saliva-coronavirus-test-now-available/2360155/

which cites a $150 home test, more accurate than the nasal or mouth swab with a less than two percent margin of error.      that you send off --


obviously not a candidate for patient testing at that price for most of us!!

stog

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ok this link gives more info on the Curative tests https://dot.la/coronavirus-rapid-test-curative-los-angeles-2645906983.html

includes the "Are you concerned that you have too high of a false negative rate at 10%?"

and

At one point, Curative was attempting to roll out at-home testing and then had to pull back after FDA warnings. Will you be making home testing kits again?

Quote
I can't give a time estimate but we are actively working with the FDA right now. I think their concern is "can people adequately collect the sample, or will they do it wrong, and then get a negative test result," which is incorrect. Our plan is to use telemedicine observation. What we've seen in our clinical studies is that if you give people the chance to do it wrong, they will do it wrong. In fact when you have somebody observing, they read the instructions better and they collect a better sample. We're still working on the pricing and potentially looking at whether there is federal or state reimbursement for some of that testing and the potential of billing insurance.


interesting read
« Last Edit: May 14, 2020, 11:59:01 AM by stog »