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The Mayo has two tests, COR2G (to be discontinued 6/10) and VCOV2 (its successor).
The bikur cholim test was the OLD COR2G test (it will say this on the results)
for COR2G test:
Less than 1.01 is negative
between 1.01 and 1.20 is indecisive
more than 1.2 is positive

« Last edited by junion on May 31, 2020, 07:54:25 PM »

Poll

Did you have antibodies?

Symptomatic, previously confirmed COVID positive, positive for antibodies
23 (13.4%)
Asymptomatic, previously confirmed COVID positive, positive for antibodies
1 (0.6%)
Symptomatic but no previous positive test, positive for antibodies
56 (32.6%)
No symptoms or previous positive test, positive for antibodies
11 (6.4%)
Symptomatic, previously confirmed COVID positive, negative for antibodies
2 (1.2%)
Asymptomatic, previously confirmed COVID positive, negative for antibodies
0 (0%)
Symptomatic but no previous positive test, negative for antibodies
24 (14%)
No symptoms or previous positive test, negative for antibodies
55 (32%)

Total Members Voted: 166

Author Topic: Did you test for antibodies? POLL  (Read 52639 times)

Offline ckey

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Re: Did you test for antibodies? POLL
« Reply #260 on: May 27, 2020, 12:03:08 AM »
http://www.epitopediagnostics.com/covid-19-elisa

https://www.sciencedirect.com/science/article/pii/S1386653220301360?via%3Dihub

https://www.mayocliniclabs.com/test-catalog/Performance/609035

http://www.epitopediagnostics.com/covid-19-elisa

https://www.sciencedirect.com/science/article/pii/S1386653220301360?via%3Dihub

Dan posted these pages demonstrating that mayo clinic is only 88 percent accurate. Anyone can help interpret these pages?@biobook?

Not quite.
https://www.dansdeals.com/more/dans-commentary/news-roundup/covid-19-news-roundup-5-25-20-super-spreaders-second-wave-immunity-passports-el-al-turkey-worldwide-restrictions-roundup-amare-stoudemire/

I said "88% specificity for COVID-19."

All these quotes seem to be assuming that all ELISA tests are the same, since not a single link mentioned above is referring to the Mayo Clinic's test. I am a layman but I believe this assumption is wrong. ELISA is just the technology used, but each test is different with a different accuracy. Compare the FDA's EUA list which has numerous ELISA tests with varying accuracy: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance

I still don't see anything anywhere about the Mayo Clinic's original COR2G test that Bikur Cholim used with regard to sensitivity or specificity. If anyone can find these numbers please let me know.

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Re: Did you test for antibodies? POLL
« Reply #261 on: May 27, 2020, 12:20:57 AM »
All these quotes seem to be assuming that all ELISA tests are the same, since not a single link mentioned above is referring to the Mayo Clinic's test. I am a layman but I believe this assumption is wrong. ELISA is just the technology used, but each test is different with a different accuracy. Compare the FDA's EUA list which has numerous ELISA tests with varying accuracy: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance

I still don't see anything anywhere about the Mayo Clinic's original COR2G test that Bikur Cholim used with regard to sensitivity or specificity. If anyone can find these numbers please let me know.

https://www.mayocliniclabs.com/test-catalog/Performance/609035
"(Package insert: EDI Novel Coronavirus COVID-19 IgG ELISA Kit, Epitope Diagnostics, Inc., KT-1032/IVD/US-ONLY-1. 03/2020)"

https://www.sciencedirect.com/science/article/pii/S1386653220301360?via%3Dihub
"specificity of...88.7% for the...EDI assay.
...We also noticed that the EDI assay has a smaller range of linearity compared to both of the other tests preventing the proportional detection of a further increase of antibody titers with time....
The strength of the EDI assay is its high sensitivity; however, we found a comparatively low specificity and narrow linear range..."

http://www.epitopediagnostics.com/covid-19-elisa
"EDI™ Novel Coronavirus COVID-19 ELISA Kits Enzyme Linked Immunosorbent Assays (ELISA) for the qualitative detection of the COVID-19 IgG and IgM in human serum."

It's also not listed as having an EUA: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance
Save your time, I don't answer PM. Post it in the forum and a dedicated DDF'er will get back to you as soon as possible.

Offline biobook

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Re: Did you test for antibodies? POLL
« Reply #262 on: May 27, 2020, 01:08:00 AM »
JerseySteve quoted upthread the Mayo Clinic's May 20 announcement of their new assay, with EUA. https://forums.dansdeals.com/index.php?topic=116518.msg2260692#msg2260692

This is probably the newer version:
https://askmayoexpert.mayoclinic.org/topic/clinical-answers/gnt-20485827/sec-20485853

"Based on studies of the serologic antibody test used internally at Mayo Clinic:
Test sensitivity is 100% after 14 days of symptoms in hospitalized patients, and 92% after 20 days of symptoms in patients with milder disease
Test specificity is approximately 97%"

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Re: Did you test for antibodies? POLL
« Reply #263 on: May 27, 2020, 01:27:32 AM »
https://www.mayocliniclabs.com/test-catalog/Performance/609035
"(Package insert: EDI Novel Coronavirus COVID-19 IgG ELISA Kit, Epitope Diagnostics, Inc., KT-1032/IVD/US-ONLY-1. 03/2020)"

https://www.sciencedirect.com/science/article/pii/S1386653220301360?via%3Dihub
"specificity of...88.7% for the...EDI assay.
...We also noticed that the EDI assay has a smaller range of linearity compared to both of the other tests preventing the proportional detection of a further increase of antibody titers with time....
The strength of the EDI assay is its high sensitivity; however, we found a comparatively low specificity and narrow linear range..."

http://www.epitopediagnostics.com/covid-19-elisa
"EDI™ Novel Coronavirus COVID-19 ELISA Kits Enzyme Linked Immunosorbent Assays (ELISA) for the qualitative detection of the COVID-19 IgG and IgM in human serum."

Thank you, that's very helpful to connect the dots. Interestingly, its high claimed sensitivity seems to be counter to quite a lot of anecdotal evidence.

It's also not listed as having an EUA: https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance

...which is probably why Mayo is switching to the new VCOV2 test which has an EUA instead of the COR2G that Bikur Cholim used: https://news.mayocliniclabs.com/covid19/

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Re: Did you test for antibodies? POLL
« Reply #264 on: May 27, 2020, 01:28:29 AM »
JerseySteve quoted upthread the Mayo Clinic's May 20 announcement of their new assay, with EUA. https://forums.dansdeals.com/index.php?topic=116518.msg2260692#msg2260692

This is probably the newer version:
https://askmayoexpert.mayoclinic.org/topic/clinical-answers/gnt-20485827/sec-20485853

"Based on studies of the serologic antibody test used internally at Mayo Clinic:
Test sensitivity is 100% after 14 days of symptoms in hospitalized patients, and 92% after 20 days of symptoms in patients with milder disease
Test specificity is approximately 97%"

This is their new test, which at least has an FDA EUA

Ortho-Clinical Diagnostics VITROS Anti-SARS-CoV-2 IgG test

Developer: Ortho-Clinical Diagnostics, Inc.
Test: VITROS Anti-SARS-CoV-2 IgG test
Technology: High Throughput CLIA
Target: Spike

Antibody   Performance Measure   Estimate of Performance   95% Confidence Interval
IgG   Sensitivity (PPA)   90.0% (36/40)   (76.9%; 96.0%)
IgG   Specificity (NPA)   100% (407/407)   (99.1%; 100%)
IgG   PPV at prevalence = 5%   100%   (81.8%; 100%)
IgG   NPV at prevalence = 5%   99.5%   (98.8%; 99.7%)
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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« Last Edit: May 27, 2020, 11:18:59 AM by aygart »
Feelings don't care about your facts

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Re: Did you test for antibodies? POLL
« Reply #266 on: May 27, 2020, 11:29:07 AM »
https://www.forbes.com/sites/tommybeer/2020/05/26/cdc-says-possibly-less-than-half-of-positive-antibody-tests-are-correct/
https://www.cnn.com/2020/05/26/health/antibody-tests-cdc-coronavirus-wrong/index.html
I am not anti media, but these articles are complete lies.

https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html
Quote
For example, in a population where the prevalence is 5%, a test with 90% sensitivity and 95% specificity will yield a positive predictive value of 49%

The good tests are 100% reliable.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #267 on: May 27, 2020, 11:37:56 AM »
I am not anti media, but these articles are complete lies.

https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html
The good tests are 100% reliable.
Good point. They are definitely higher than those articles are making it based on an example, but no they are not at 100%.

https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance
Feelings don't care about your facts

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Re: Did you test for antibodies? POLL
« Reply #268 on: May 27, 2020, 11:42:08 AM »
Good point. They are definitely higher than those articles are making it based on an example, but no they are not at 100%.

https://www.fda.gov/medical-devices/emergency-situations-medical-devices/eua-authorized-serology-test-performance
The Abott test which is prevalent has 99% specificity which gives an 84% Predictive value according to the FDA.

The German made Euroimmune & Roche tests do indeed have 100% specificity, which give a 100% Positive predictive value (and the FDA notes that in the link you posted).

The Forbes article is complete bogus.


ETA I made a mistake. While Euroimmune does have 100% specificity (80/80), Roche only has 99.8% (5262/5272), so the FDA calculates their PPV at 5% prevalence as 96.5%.

I spoke to Euroimmune and their test is readily available in German labs. I doubt it's actually better than Roche though.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #269 on: May 27, 2020, 11:43:45 AM »
I am not anti media, but these articles are complete lies.

https://www.cdc.gov/coronavirus/2019-ncov/lab/resources/antibody-tests-guidelines.html
The good tests are 100% reliable.

I believe this is how the authors came to their conclusions:

Quote
In most of the country, including areas that have been heavily impacted, the prevalence of SARS-CoV-2 antibody is expected to be low, ranging from <5% to 25%, so that testing at this point might result in relatively more false positive results and fewer false-negative results.

Quote
Testing strategies
In the current pandemic, maximizing specificity and thus positive predictive value in a serologic algorithm is preferred in most instances, since the overall prevalence of antibodies in most populations is likely low. For example, in a population where the prevalence is 5%, a test with 90% sensitivity and 95% specificity will yield a positive predictive value of 49%. In other words, less than half of those testing positive will truly have antibodies. Alternatively, the same test in a population with an antibody prevalence exceeding 52% will yield a positive predictive greater than 95%, meaning that less than one in 20 people testing positive will have a false positive test result.
Failing at maintaining Lurker status.

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Re: Did you test for antibodies? POLL
« Reply #270 on: May 27, 2020, 11:46:19 AM »
I believe this is how the authors came to their conclusions:
I know exactly how they came to their conclusion. The CDC website says 49%.

But the CDC says that about tests with low specificity, and there are tests with 100% specificity, or close.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #271 on: May 27, 2020, 11:46:48 AM »
The German made Euroimmune & Roche tests do indeed have 100% specificity, which give a 100% Positive predictive value (and the FDA notes that in the link you posted).

ETA I made a mistake. While Euroimmune does have 100% specificity (80/80), Roche only has 99.8% (5262/5272), so the FDA calculates their PPV at 5% prevalence as 96.5%.

I spoke to Euroimmune and their test is readily available in German labs. I doubt it's actually better than Roche though.
Waiting to hear from anyone in the US with these tests.
Save your time, I don't answer PM. Post it in the forum and a dedicated DDF'er will get back to you as soon as possible.

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Re: Did you test for antibodies? POLL
« Reply #272 on: May 27, 2020, 11:48:46 AM »
Waiting to hear from anyone in the US with these tests.
Working on a solution to ship specimens. Will keep you posted.

https://www.worldcourier.com can do it, but need to set up an account first.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #273 on: May 27, 2020, 11:49:11 AM »
I know exactly how they came to their conclusion. The CDC website says 49%.

But the CDC says that about tests with low specificity, and there are tests with 100% specificity, or close.

IINM, the test Mayo was using until last week had 88% specificity.
Failing at maintaining Lurker status.

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Re: Did you test for antibodies? POLL
« Reply #274 on: May 27, 2020, 11:53:46 AM »
This is their new test, which at least has an FDA EUA

Ortho-Clinical Diagnostics VITROS Anti-SARS-CoV-2 IgG test

Developer: Ortho-Clinical Diagnostics, Inc.
Test: VITROS Anti-SARS-CoV-2 IgG test
Technology: High Throughput CLIA
Target: Spike

Antibody   Performance Measure   Estimate of Performance   95% Confidence Interval
IgG   Sensitivity (PPA)   90.0% (36/40)   (76.9%; 96.0%)
IgG   Specificity (NPA)   100% (407/407)   (99.1%; 100%)
IgG   PPV at prevalence = 5%   100%   (81.8%; 100%)
IgG   NPV at prevalence = 5%   99.5%   (98.8%; 99.7%)
Interestingly, the same company has a different assay with better numbers

Ortho-Clinical Diagnostics VITROS Immunodiagnostic Products Anti-SARS-CoV-2 Total Reagent Pack and Calibrator

Developer: Ortho-Clinical Diagnostics, Inc.
Test: VITROS Immunodiagnostic Products Anti-SARS-CoV-2 Total Reagent Pack and Calibrator
Technology: High Throughput CLIA
Target: Spike

Antibody   Performance Measure   Estimate of Performance    95% Confidence Interval
Pan-Ig   Sensitivity (PPA)   100% (49/49)   (92.7%; 100%)
Pan-Ig   Specificity (NPA)   100% (400/400)   (99.0%; 100%)
Pan-Ig   PPV at prevalence = 5%   100%   (83.0.%; 100%)
Pan-Ig   NPV at prevalence = 5%   100%   (99.6%; 100%)

IINM, the test Mayo was using until last week had 88% specificity.
You're not mistaken, I'm the one who posted it a few pages up. My guess is Mayo is using tests that the lesser known companies are giving them for free in order to help marketing.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #275 on: May 27, 2020, 01:25:31 PM »
In the beginning I was dissapointed that  I got the Quest/Abbott labs test and not one with a number, as time goes by it seems the one I took is highly accurate (on a positive result) and the others are iffy. The whole number game seems to be very unclear.

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Re: Did you test for antibodies? POLL
« Reply #276 on: May 27, 2020, 01:30:45 PM »
In the beginning I was dissapointed that  I got the Quest/Abbott labs test and not one with a number, as time goes by it seems the one I took is highly accurate (on a positive result) and the others are iffy. The whole number game seems to be very unclear.
If you're positive and aren't confident enough, just get another one.
״וזה כלל גדול: שישנא אדם כל דבר שקר. וכל מה שיוסיף שנאה לדרכי השקר – יוסיף אהבה לתורה.״ - אורחות צדיקים

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Re: Did you test for antibodies? POLL
« Reply #277 on: May 27, 2020, 01:46:38 PM »
If you're positive and aren't confident enough, just get another one.
I would take another test to get a number as the Quest only gave me a positive result, I do not see any point in taking the labcorp test as the Quest is almost 100% accurate.

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Re: Did you test for antibodies? POLL
« Reply #278 on: May 27, 2020, 01:59:24 PM »
Apparently in can take as much as 40 days to produce antibodies after contracting covid so those with negative results may want to give it more time.
https://news.google.com/articles/CAIiEHObZGGb_-G4lY7jpKlm0kAqGQgEKhAIACoHCAow4uzwCjCF3bsCMIrOrwM?hl=en-US&gl=US&ceid=US%3Aen

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Re: Did you test for antibodies? POLL
« Reply #279 on: May 27, 2020, 09:44:58 PM »