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New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

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Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#41

Post by [deleted] »

jedberg wrote: post #39
cerebral_oasis wrote: post #38

I took this antibody test through LabCorp on Friday and tested positive. I have been in strict (see: paranoid) isolation with one other person since March 7 and haven't felt sick or anything close to it since then. I did have what I thought was a strange flu/cold early February with a sore throat, post-nasal drip, wildly varying body temperature, and lower back pains. In hindsight those are COVID-19 symptoms. the per…

I've been waiting for a decent serum test because both my wife and I had "the flu" with symptoms consistent with COVID-19, me in mid-January and her in late February. How did you get the test?

[deleted]

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#42

Post by tptacek »

These stats are generated just a couple weeks after symptoms or PCR test positivity. I'm still wondering how specificity might drop off for much earlier exposures. Anecdotally: people on my Fb feed are getting positive tests they attribute to illnesses they had back in January and February.

(This concern has nothing to do with the benefit these tests have in "real time" testing).

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#43

Post by cerebral_oasis »

jedberg wrote: post #39
cerebral_oasis wrote: post #38

I took this antibody test through LabCorp on Friday and tested positive. I have been in strict (see: paranoid) isolation with one other person since March 7 and haven't felt sick or anything close to it since then. I did have what I thought was a strange flu/cold early February with a sore throat, post-nasal drip, wildly varying body temperature, and lower back pains. In hindsight those are COVID-19 symptoms. the per…

I've been waiting for a decent serum test because both my wife and I had "the flu" with symptoms consistent with COVID-19, me in mid-January and her in late February. How did you get the test?

https://www.labcorp.com/antibody-testing

$10 for a "virtual assessement" and ~$100 for the test for uninsured, but my insurance covered it. I scheduled it same day and it took a total of 20 minutes in and out with blood draw. I received my results via email in 2 days.

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#45

Post by misun78 »

binarymax wrote: post #21
klmadfejno wrote: post #10

Earlier quoted context omitted.

What's wrong with 10% of them being false positives? (also I think it's 9%)

Because with a false positive antibody test then you can still contract and be a carrier. This is a problem for the immunity passport proposals (which I think are a terrible idea anyway, but that’s beside the point)

Why do you think immunity passports are a terrible idea? What else works better barring a long term vaccine?

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#46

Post by rindalir »

It's interesting -- in the paper it says that the samples they used to assess the sensitivity (it was a different population for specificity) were from people who had (mostly) been elderly and hospitalized, and that they do not know how it would perform in subclinical or asymptomatic cases. I admit being super not-objective about my reading, since I had this test done last week and came back negative despite losing my sense of smell completely in late March - early April (I live in Boston and was exposed to people who tested positive). It will be interesting to see more data on the Abbott and Roche tests on the subclinical / asymptomatic population.

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#47

Post by ghshephard »

barbegal wrote: post #22

> We tested 1,020 serum specimens collected prior to SARS-CoV-2 circulation in the United States and found one false positive This gives 95% confidence intervals of between 0.0% and 0.5% false positive rate.

Okay - I'm going to reveal my statistics ignorance here - but if they did get a false positive, how does 0.0% fall within the range of possibilities (or is that allowing for it might be 0.0499..% or lower?)

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#48

Post by mercurywells »

ummonk wrote: post #35

The sample sizes are too small to claim such high specificity and sensitivity without any error bars.

> The sensitivity of the assay from the estimated day of symptom onset for the 125 patients included in our chart-review study was 53.1% (95%CI 39.4%-66.3%) at 7 days, 82.4% (51.0-76.4%) at 10 days, 96.9% (89.5-99.5%) at 14 days, and 100% (95.1%-100%) at day 17 using the manufacturer’s recommended cutoff of 1.4.

> The sensitivity from the date of PCR positivity was: 88.7% (78.5-94.4%) at 7 days, 97.2% (90.4-99.5%) at 10 days, 100.0% at 14 days (95.4-100.0%), and 100.0% (95.5-100.0%) at 17 days using the manufacturer’s recommended cutoff of 1.4.

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#49

Post by InvaderFizz »

gwd wrote: post #23
wtvanhest wrote: post #7

Earlier quoted context omitted.

Would you or someone else mind expanding on this thought a little? Why does 99.9% specificity mean that 10% will be false positives? {added: great answers below} well worth understanding this point. In short specificity measures the % of the population tested which had false positives, but doesn't give you the ratio of false positives to positives or the probability that a positive test means you actually have the an…

Let me give it a try. Suppose we have 100,000 people in a statistically representative town. If 1% of people have had COVID-19, then that's 1000 people who have had it, and 99,000 people who haven't. The test has a sensitivity of 100%, which means all 1000 people who've had it will test positive. The test has a specificity of 99.9%, which means 98,901 of the 99,000 people who haven't had it will test negative; but th…

So if I'm understanding this correctly, with this test.

If you test negative, you are clear, guaranteed, no false negatives.

If you test positive, there is a 10% chance it's a false positive.

I guess my follow up question, does a retest of the positive population make that false positive rate drop to 0.1%, or is the reason for false positive significant to an individual and not random chance?

Re: New Abbott SARS-CoV-2 antibody test has 99.90% specificity and 100% sensitivity

#50

Post by chime »

cerebral_oasis wrote: post #38

I took this antibody test through LabCorp on Friday and tested positive. I have been in strict (see: paranoid) isolation with one other person since March 7 and haven't felt sick or anything close to it since then. I did have what I thought was a strange flu/cold early February with a sore throat, post-nasal drip, wildly varying body temperature, and lower back pains. In hindsight those are COVID-19 symptoms. the per…

Did your doctor have to refer you to LabCorp? I read that LabCorp doesn't want any walk-ins.
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