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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

#51

Post by richardwhiuk »

ghshephard wrote: post #47
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?)

Rounding - 0.000000001% is treated as 0.0%.

(More likely, 0.04% or similar is being treated as 0.0%, but I haven't done the maths to confirm what the number would be)

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

#52

Post by jariel »

'Specificity and Sensitivity' are new words that are now going to enter the public consciousness with regards to testing.

Before Iraq War 2, in 2003, absolutely nobody knew the difference between a 'Shia' or 'Sunni' Muslim, and then it became more common knowledge.

It's neat to see how these events shape awareness.

Now every time a Nurse does a test, people will ask "What's the specificity?!" which can be a good or bad thing.

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

#53

Post by danans »

It seems like a voluntary test for someone without symptoms is of limited value to the individual (beyond their individual curiosity) since we don't know enough either way about reinfection risk at this point, and the result is not terribly actionable - you can't just walk into stores without a mask because you have a positive antibody test - nobody is going to trust your lab result printout as a reason to avoid public health measures.

But that said, there should be a public health benefit to broad antibody testing to understand the true infection rate, and for that reason alone, seems like tests like this should be covered by insurance or the public purse for everyone - at least in areas with outbreaks or at high risk for outbreaks.

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

#54

Post by lbeltrame »

danans wrote: post #53

It seems like a voluntary test for someone without symptoms is of limited value to the individual (beyond their individual curiosity) since we don't know enough either way about reinfection risk at this point, and the result is not terribly actionable - you can't just walk into stores without a mask because you have a positive antibody test - nobody is going to trust your lab result printout as a reason to avoid publ…

The FDA suggestion of doing two tests to reduce the percentage of false positives (since you can't rule out cross-reactivity with another coronavirus) looks like a good idea for broad testing.

Of course this means higher costs.

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

#55

Post by rootusrootus »

cma wrote: post #34
pjc50 wrote: post #31

Earlier quoted context omitted.

Reminder that at the moment this cannot happen without 1% of them dying and many more suffering long lasting or even permanent debilitation. If we ever get to the point where 80% of the population has had the virus, that would be a massive failure.

And the immunity may only last a year or two.

Unless everyone's immunity stops at about the same time, a year or two of immunity would be sufficient to prevent large scale pandemics from recurring from this virus.

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

#56

Post by IfOnlyYouKnew »

ghshephard wrote: post #47
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?)

Not ignorant at all... I believe the issue is that the statement ("95% confidence interval of 0.0 to 0.5") has just slightly different/counterintuitive meaning in this case. In general, you can always make the interval larger, but you want it to be smaller. With the understanding that the 95% is a lower bound, [0.0, 25%] is also a valid confidence interval.

But, yes, you are entirely correct as to the practical meaning. 0% itself is impossible, but 0.0...1% could still happen.

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

#57

Post by lbeltrame »

projektfu wrote: post #16
pgcudahy wrote: post #6

There seems to be no analysis of whether these are neutralizing antibodies. The idea of using serology for immunity certificates or "golden tickets" is never going to go well. Even with 99.9% specificity, if the population prevalence is 1%, 10% of positives will be false positives. If in real world testing, specificity is 99% and population prevalence is 1%, then 50% of positives are false positives.

If you want neutralizing antibodies you can do serum virus neutralization assay. It's more complicated and takes longer. Testing doesn't need to be 100% to be effective, but it does need to be better than random chance. A mixture of contact tracing, PCR testing, antibody testing and effective quarantines could be used to make the virus go away, but would require a coordinated strategy that the US has not attempted to…

The people from the Duke-NUS Medical School have designed a "surrogate virus neutralization test"[1] which might be used to perform neutralization tests without the security requirements of using live virus.

[1] https://www.researchsquare.com/article/rs-24574/v1

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

#58

Post by MertsA »

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)

It doesn't have to be perfect. If 90% of the at risk population where it's allowed to spread has immunity, then that's high enough that the virus would logarithmically decay. That's often referred to as "herd immunity". So long as on average cases result in less than one additional case you're fine. 1000 cases with an uninhibited net reproductive rate of 4 with a population that's 90% immune would result in the next "generation" having 400, then 160, then 64, then 26.... You get the point.

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

#59

Post by luhn »

lbeltrame wrote: post #54
danans wrote: post #53

It seems like a voluntary test for someone without symptoms is of limited value to the individual (beyond their individual curiosity) since we don't know enough either way about reinfection risk at this point, and the result is not terribly actionable - you can't just walk into stores without a mask because you have a positive antibody test - nobody is going to trust your lab result printout as a reason to avoid publ…

The FDA suggestion of doing two tests to reduce the percentage of false positives (since you can't rule out cross-reactivity with another coronavirus) looks like a good idea for broad testing. Of course this means higher costs.

> since you can't rule out cross-reactivity with another coronavirus

If that causes a false positive, wouldn't a second test yield the same result?

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

#60

Post by Alex3917 »

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…

Where does it say that LabCorp uses the Abbott Architect platform? Couldn't find it on their website. (Unlike, say, healthlabs.com)
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