5 ms·

A take it or leave it anecdote for you: I was chatting with an actuary working in life insurance field who is heavily involved in the pandemic industry groups.

by JTon 6y ago

A take it or leave it anecdote for you: I was chatting with an actuary working in life insurance field who is heavily involved in the pandemic industry groups. The actuary told me the antibody test is considered unreliable and has as high as 50% false negative rate.

entee 6y ago
There are different tests out there, many are pretty bad. Some are pretty good, for example Abbott's clears 90% in both specificity and sensitivity. That said, given a low prevalence of the disease, this is actually fairly likely to give false positives. 93.8% sensitivity suggests the false negative rate should be pretty low with that test. https://www.360dx.com/immunoassays/study-finds-abbott-coronavirus-serology-test-more-accurate-euroimmun-test#.Xt6qhy2z1MY https://www.360dx.com/immunoassays/study-finds-abbott-corona...
- djsumdog 6y ago
  Not to mention the PCR tests and the antibody tests got combined into "total cases" in several data sets, mucking the numbers: https://www.theatlantic.com/health/archive/2020/05/cdc-and-states-are-misreporting-covid-19-test-data-pennsylvania-georgia-texas/611935/ https://www.theatlantic.com/health/archive/2020/05/cdc-and-s...
NotSammyHagar 6y ago
Anecdotes aren't worth much in this area. There's no conspiracy of silence about problems. We can use actual science. They actually test the quality of these tests. Some are better than others. For example, the Abbott test has a surprising accuracy [1] "Researchers at the University of Washington School of Medicine found Abbott’s test had a specificity rate of 99.9% and a sensitivity rate of 100%, suggesting very few chances of incorrectly diagnosing a healthy person with the infection and no false negatives." 1. https://www.cnbc.com/2020/05/08/study-suggests-abbott-covid-19-antibody-test-highly-likely-to-give-correct-results.html https://www.cnbc.com/2020/05/08/study-suggests-abbott-covid-...
- 9nGQluzmnq3M 6y ago
  COVID test accuracy is very similar to condom effectiveness: they're both high in theory, but surprisingly low in practice, not because of the science but user error. I've seen estimates as high as 10-30% for false negatives, largely due to poor swabbing practices: https://www.healthline.com/health-news/false-negatives-covid19-tests-symptoms-assume-you-have-illness https://www.healthline.com/health-news/false-negatives-covid...
  - jccooper 6y ago
    That's not the sort of test under discussion here. The Abbot test and other antibody tests are blood based. I'm sure there are things in the pipeline that can go wrong, but they're much less susceptible to error. What is important is that antibodies are a sufficient but not necessary indication of past infection. There seem to be plenty of people who don't develop them when exposed, possibly due to effective T-cell immunity.
  - Rebelgecko 6y ago
    FWIW I think most if not all of the antibody tests are done on blood
  - disabled 6y ago
    The Abbott test mentioned above is blood drawn from serum (not a fingerprick blood test!). This is not the nasal swab test that sometimes misses positive people, as you mentioned. To avoid confusion over this issue: There is an Abbott nasal swab test, that gives results 15 minutes after being swabbed, and without "special equipment". That specific Abbott test (the instant nasal swab) has experienced dubious results in practice, even compared to more standard nasal swab tests.
  - hsitz 6y ago
    First, if you're talking about swabbing, then I think you're talking about the test to see whether a person is currently infected with the virus. That's what the article you linked was regarding. The antibody tests are a different animal. They test to see whether you might have been infected in the past, by looking for antibodies in your blood. So these are blood tests, and, I expect, have less chance for user error. But also, I think lots of covid antibody tests are not high accuracy even "in theory". It seems the FDA relaxed oversight on companies producing antibody tests: ". . . after being criticized for the fumbled rollout of diagnostic tests during the start of a global pandemic, the FDA swung hard in the other direction, waiving its usual requirements and letting firms rush self-validated [antibody] tests into the market."[1] So there are antibody tests from over 200 companies out there. Some of these antibody tests are quite accurate, high sensitivity and specificity. Others, not so much. [1] https://khn.org/news/hype-collides-with-science-as-fda-tries-to-rein-in-wild-west-of-covid-blood-tests/ https://khn.org/news/hype-collides-with-science-as-fda-tries...
djsumdog 6y ago
Not so anecdotal: There is an Oncology professor in the UK who tested his staff of 200 and got ~10% for antibodies. A month later he expected 30%, but still got around 10% (https://unherd.com/thepost/professor-karol-sikora-fear-is-more-dangerous-than-the-virus/ https://unherd.com/thepost/professor-karol-sikora-fear-is-mo...) There is a chance antibodies for this simply do not last very long, or that many people fight it off before it reaches the adaptive immune system and requires antibodies (there are many layers that have evolved in our immune systems). There are many other viruses that don't produce long lasting immunity as well. Hepatitis B vaccines require 3 shots within a few months and even then, the take rate for it is only around 60%.
- lostlogin 6y ago
  That link is rather dubious. eg "When the history books are written, the fear will have done much more damage than the virus". This is easy to say when you're one able to read the history book. It's all going to depend on what ones acceptable death rate is, and that gets dark pretty fast.
  - acdha 6y ago
    The author also has a history of controversy which definitely makes me want to take anything with a grain of salt: https://en.wikipedia.org/wiki/Karol_Sikora https://en.wikipedia.org/wiki/Karol_Sikora There’s likely a reason why that’s on a conservative business’s vanity site and not a scientific journal.
three_seagrass 6y ago
Neither being an actuary or insurance adjuster makes you an expert on clinical lab tests. My guess is the person you were chatting with heard some hyperbolic statistic about ELIZA tests and is repeating it.

by JTon 6y ago

entee 6y ago

There are different tests out there, many are pretty bad. Some are pretty good, for example Abbott's clears 90% in both specificity and sensitivity. That said, given a low prevalence of the disease, this is actually fairly likely to give false positives. 93.8% sensitivity suggests the false negative rate should be pretty low with that test. https://www.360dx.com/immunoassays/study-finds-abbott-coronavirus-serology-test-more-accurate-euroimmun-test#.Xt6qhy2z1MY https://www.360dx.com/immunoassays/study-finds-abbott-corona...

djsumdog 6y ago
Not to mention the PCR tests and the antibody tests got combined into "total cases" in several data sets, mucking the numbers: https://www.theatlantic.com/health/archive/2020/05/cdc-and-states-are-misreporting-covid-19-test-data-pennsylvania-georgia-texas/611935/ https://www.theatlantic.com/health/archive/2020/05/cdc-and-s...

NotSammyHagar 6y ago

Anecdotes aren't worth much in this area. There's no conspiracy of silence about problems. We can use actual science. They actually test the quality of these tests. Some are better than others. For example, the Abbott test has a surprising accuracy [1] "Researchers at the University of Washington School of Medicine found Abbott’s test had a specificity rate of 99.9% and a sensitivity rate of 100%, suggesting very few chances of incorrectly diagnosing a healthy person with the infection and no false negatives." 1. https://www.cnbc.com/2020/05/08/study-suggests-abbott-covid-19-antibody-test-highly-likely-to-give-correct-results.html https://www.cnbc.com/2020/05/08/study-suggests-abbott-covid-...

9nGQluzmnq3M 6y ago
COVID test accuracy is very similar to condom effectiveness: they're both high in theory, but surprisingly low in practice, not because of the science but user error. I've seen estimates as high as 10-30% for false negatives, largely due to poor swabbing practices: https://www.healthline.com/health-news/false-negatives-covid19-tests-symptoms-assume-you-have-illness https://www.healthline.com/health-news/false-negatives-covid...
- jccooper 6y ago
  That's not the sort of test under discussion here. The Abbot test and other antibody tests are blood based. I'm sure there are things in the pipeline that can go wrong, but they're much less susceptible to error. What is important is that antibodies are a sufficient but not necessary indication of past infection. There seem to be plenty of people who don't develop them when exposed, possibly due to effective T-cell immunity.
- Rebelgecko 6y ago
  FWIW I think most if not all of the antibody tests are done on blood
- disabled 6y ago
  The Abbott test mentioned above is blood drawn from serum (not a fingerprick blood test!). This is not the nasal swab test that sometimes misses positive people, as you mentioned. To avoid confusion over this issue: There is an Abbott nasal swab test, that gives results 15 minutes after being swabbed, and without "special equipment". That specific Abbott test (the instant nasal swab) has experienced dubious results in practice, even compared to more standard nasal swab tests.
- hsitz 6y ago
  First, if you're talking about swabbing, then I think you're talking about the test to see whether a person is currently infected with the virus. That's what the article you linked was regarding. The antibody tests are a different animal. They test to see whether you might have been infected in the past, by looking for antibodies in your blood. So these are blood tests, and, I expect, have less chance for user error. But also, I think lots of covid antibody tests are not high accuracy even "in theory". It seems the FDA relaxed oversight on companies producing antibody tests: ". . . after being criticized for the fumbled rollout of diagnostic tests during the start of a global pandemic, the FDA swung hard in the other direction, waiving its usual requirements and letting firms rush self-validated [antibody] tests into the market."[1] So there are antibody tests from over 200 companies out there. Some of these antibody tests are quite accurate, high sensitivity and specificity. Others, not so much. [1] https://khn.org/news/hype-collides-with-science-as-fda-tries-to-rein-in-wild-west-of-covid-blood-tests/ https://khn.org/news/hype-collides-with-science-as-fda-tries...

djsumdog 6y ago

Not so anecdotal: There is an Oncology professor in the UK who tested his staff of 200 and got ~10% for antibodies. A month later he expected 30%, but still got around 10% (https://unherd.com/thepost/professor-karol-sikora-fear-is-more-dangerous-than-the-virus/ https://unherd.com/thepost/professor-karol-sikora-fear-is-mo...) There is a chance antibodies for this simply do not last very long, or that many people fight it off before it reaches the adaptive immune system and requires antibodies (there are many layers that have evolved in our immune systems). There are many other viruses that don't produce long lasting immunity as well. Hepatitis B vaccines require 3 shots within a few months and even then, the take rate for it is only around 60%.

lostlogin 6y ago
That link is rather dubious. eg "When the history books are written, the fear will have done much more damage than the virus". This is easy to say when you're one able to read the history book. It's all going to depend on what ones acceptable death rate is, and that gets dark pretty fast.
- acdha 6y ago
  The author also has a history of controversy which definitely makes me want to take anything with a grain of salt: https://en.wikipedia.org/wiki/Karol_Sikora https://en.wikipedia.org/wiki/Karol_Sikora There’s likely a reason why that’s on a conservative business’s vanity site and not a scientific journal.

three_seagrass 6y ago

Neither being an actuary or insurance adjuster makes you an expert on clinical lab tests. My guess is the person you were chatting with heard some hyperbolic statistic about ELIZA tests and is repeating it.