6 ms·

Everyone keeps pointing to the lack of availability of kits in the US without mentioning the reason. The reason is that the CDC created its own kits instead of

Everyone keeps pointing to the lack of availability of kits in the US without mentioning the reason. The reason is that the CDC created its own kits instead of using the WHO kits. Why did they do that? Because the WHO kits were inaccurate. Accurate diagnoses happened only ~60% of the time, basically a coin flip. In China the tests were becoming such a problem, now they basically just count anyone with symptoms. That's one of the reasons why numbers jumped drastically. Sometimes it takes up to 8 times to get a hit. Which when you think about it is completely ridiculous. That is with people with full blown symptoms. The original CDC batch became tainted but were more accurate...unfortunately the CDC version was also giving false positives and didn't meet QC. To make matters worse CDC rules required very stringent guidelines for approval from third parties and states. Most of that has been lifted (I think this is what Trump was referring to when he said he was lifting something from the Obama admin, though I don't think it started with him. But who knows because Trump is often full of bluster.) Here are a few articles about it. https://www.livescience.com/coronavirus-testing-kits-flawed.html https://www.livescience.com/coronavirus-testing-kits-flawed.... https://www.bbc.com/news/health-51491763 https://www.bbc.com/news/health-51491763 https://www.propublica.org/article/cdc-coronavirus-covid-19-test https://www.propublica.org/article/cdc-coronavirus-covid-19-... I wish people would stop pointing to South Korea and China as the paradigm of how this should be treated. It's entirely possible that the "drive thru" model with relatively inaccurate kits could make things worse. There isn't much point in producing millions of tests if they are no more accurate than a coin flip and can take up to 8 times to properly diagnose someone. Not to say the US hasn't bungled this and wasted some precious time. The one thing, I'm pretty confused about at this point is how this has spread so quickly in Italy.

deleted 7y ago
[deleted]
fspeech 7y ago
"Coin flip" would imply half of the people who don't have the disease will test positive. There is no evidence for that. It is a super inept analogy. The infection is at the lung while the swabs are done to the upper respiratory tract. There will be misses no matter how good the kits are.
- kalium_xyz 7y ago
  The key point is in “basically” its a metaphor. The test kits have a 40% false positive and alternative test kits which may test using an entirely different method may improve this. If you think a 40% false positive is good I urge you to actually read the who guidelines which both state this information and recommend testing people multiple times over two weeks. Source is who technical guidelines for testing on their site.
  - fspeech 7y ago
    The key point is information (more precisely "mutual information"). A positive test gives you information that says you have it while a coin toss tells you nothing.
  - CobrastanJorji 7y ago
    A 40% false positive may be acceptable for purposes of quarantining, so long as the false negative rate is low and the percentage of healthy people being tested is relatively low. It'd be a bit like a bloom filter of quarantine. Can this person skip quarantine? Test says okay. Can this other person leave? Test says no, but that's not solid evidence that they have the disease.
    - kalium_xyz 7y ago
      It also has a large false negative, see the posts i replied to
      - CobrastanJorji 7y ago
        Oh, well in that case, yeah, I agree, that's not very useful.
  - claudeganon 7y ago
    I’ve seen no evidence of this rate of false positives, only for false negatives (which is a problem across these tests for respiratory illnesses). What’s your source on the false positive rate?
makomk 7y ago
That might be true about the accuracy of the other tests, but it's not the reason the CDC created their own. The reason, as I understand it, is simply that there was no WHO test when they started and there never would be unless some country got up off their ass and made one. As it happens Germany got their test finished first and the WHO used that, but the CDC were already well down the path of preparing and qualifying their own test for US use by that point and switching to the WHO one would mean abandoning that work and starting again.
- zaroth 7y ago
  The CDC appears to have made an over complicated test with the goal of being able to identify other SARS viruses beyond just COVID and screwed up the reagents in the process. I’m not aware of evidence that the CDC designed primers are any better, and have read anecdotal evidence that they fail basic QA tests in open source design software used for this sort of thing. This was compounded by bad regulations which hamstrung local labs from doing their own testing.
- stewbrew 7y ago
  Are you certain this wasn't some form of NIH syndrome? I don't think the German test was any more inaccurate BTW.
nl 7y ago
The links you posted don't back up your summary. The "livescience" link is a confusing story which seems to be talking about the US, CDC test: Last week, the CDC had begun to ship about 200 testing kits to labs across the U.S. and 200 more to over 30 other countries so that more facilities could conduct testing for the new coronavirus.... The CDC is working closely with the states to correct the issues in the testing kits, Messonnier said. The BBC link is about the WHO test, says no one knows what is going on but gives multiple possible explanations: One possible explanation is the tests are accurate and the patients do not have coronavirus at the time of testing Alternatively, there could be a problem with the way the tests are being conducted... There has also been some discussion about whether doctors testing the back of the throat are looking in the wrong place. A final option is the RT-PCR test for the new coronavirus is based on flawed science.... if there is a poor match between the primer and the virus in the patient, then an infected patient could get a negative result. The Propublica link is about the CDC test: The CDC designed a flawed test for COVID-19, then took weeks to figure out a fix so state and local labs could use it.
- lonelappde 7y ago
  Don't use indentation for blockquotes. HN uses indentation for non-wrapped lines non-proportional font. Use > or " or * > One possible explanation is the tests are accurate and the patients do not have coronavirus at the time of testing > Alternatively, there could be a problem with the way the tests are being conducted... There has also been some discussion about whether doctors testing the back of the throat are looking in the wrong place. > A final option is the RT-PCR test for the new coronavirus is based on flawed science.... if there is a poor match between the primer and the virus in the patient, then an infected patient could get a negative result.
joe_the_user 7y ago
1) China and Korea have effectively treated the virus, infections in both those areas have been declining. And Korea now is effectively the lowest fatality rate for any of the effected countries which points to excellent surveillance and treatment. I darn well intent to keep pointing to this. 2) Some article point to the main vector in Italy being patient left in a hospital for 36 hour before being diagnosed and treated. This allowed the disease to spread in the community where testing was not being done - kind of like the US. 3) The Chinese test may indeed might have had problems at various points (your first link is rather anecdotal, hardly proves the test was a "coin flip". Other posters note your links don't back your arguments). The American test had even more problems and still hasn't ramped up to strong production. Making tests is hard, it seems. The CDC's "your test has problems and we know we can do better" attitude looks misguided in retrospect. 4) It seems like you're doing a bunch of speculation with little evidence. I suggest you look at infection and mortality as a basis for thinking about what country is doing well or badly. [1] [1] https://covid19info.live/ https://covid19info.live/
- lern_too_spel 7y ago
  > And Korea now is effectively the lowest fatality rate for any of the effected countries which points to excellent surveillance and treatment. I darn well intent to keep pointing to this. That's misleading. Korea has the highest active case ratio of any of the hardest hit countries. The flip side of the lowest CFR coin is that Korea also has by far the lowest recovery rate of any of those countries. You need to wait for the active cases to turn into deaths or recoveries. From JHU CSSE: South Korea Confirmed: 7,382 Deaths: 50 Recovered: 118 Existing: 7,214 If you're just looking at recovery rate (also misleading), Iran seems much better than Korea: Iran Confirmed: 6,566 Deaths: 194 Recovered: 2,134 Existing: 4,238
  - joe_the_user 7y ago
    I don't know what the criteria for recovery is. My impression is there isn't much of a international standard and so the inter-country comparisons aren't that useful. Iran might have a higher recovery rate but that might be more an artifact of how they measure this. In all other measure, South Korea is doing well. Avoiding death is much unambiguous a measure. Edit: Yes, because Korea has experienced an exponential increase in cases, most cases in Korea are "new" but this is true for most other countries - though countries where they only find cases by people dying might be different but not in a good way. Edit2: Also, it is true that Korea's lower mortality is likely partly a product of Korea's widely testing and finding asymptomatic carriers. But this is also a good thing since it allows Korea to get these people to quarantine and lower the transmission rate, hence the declining rate of infection there.
cma 7y ago
I believe they run the tests multiple times and get more accuracy from the repeated runs.

deleted 7y ago

[deleted]

fspeech 7y ago

"Coin flip" would imply half of the people who don't have the disease will test positive. There is no evidence for that. It is a super inept analogy. The infection is at the lung while the swabs are done to the upper respiratory tract. There will be misses no matter how good the kits are.

kalium_xyz 7y ago
The key point is in “basically” its a metaphor. The test kits have a 40% false positive and alternative test kits which may test using an entirely different method may improve this. If you think a 40% false positive is good I urge you to actually read the who guidelines which both state this information and recommend testing people multiple times over two weeks. Source is who technical guidelines for testing on their site.
- fspeech 7y ago
  The key point is information (more precisely "mutual information"). A positive test gives you information that says you have it while a coin toss tells you nothing.
- CobrastanJorji 7y ago
  A 40% false positive may be acceptable for purposes of quarantining, so long as the false negative rate is low and the percentage of healthy people being tested is relatively low. It'd be a bit like a bloom filter of quarantine. Can this person skip quarantine? Test says okay. Can this other person leave? Test says no, but that's not solid evidence that they have the disease.
  - kalium_xyz 7y ago
    It also has a large false negative, see the posts i replied to
    - CobrastanJorji 7y ago
      Oh, well in that case, yeah, I agree, that's not very useful.
- claudeganon 7y ago
  I’ve seen no evidence of this rate of false positives, only for false negatives (which is a problem across these tests for respiratory illnesses). What’s your source on the false positive rate?

makomk 7y ago

That might be true about the accuracy of the other tests, but it's not the reason the CDC created their own. The reason, as I understand it, is simply that there was no WHO test when they started and there never would be unless some country got up off their ass and made one. As it happens Germany got their test finished first and the WHO used that, but the CDC were already well down the path of preparing and qualifying their own test for US use by that point and switching to the WHO one would mean abandoning that work and starting again.

zaroth 7y ago
The CDC appears to have made an over complicated test with the goal of being able to identify other SARS viruses beyond just COVID and screwed up the reagents in the process. I’m not aware of evidence that the CDC designed primers are any better, and have read anecdotal evidence that they fail basic QA tests in open source design software used for this sort of thing. This was compounded by bad regulations which hamstrung local labs from doing their own testing.
stewbrew 7y ago
Are you certain this wasn't some form of NIH syndrome? I don't think the German test was any more inaccurate BTW.

nl 7y ago

The links you posted don't back up your summary. The "livescience" link is a confusing story which seems to be talking about the US, CDC test: Last week, the CDC had begun to ship about 200 testing kits to labs across the U.S. and 200 more to over 30 other countries so that more facilities could conduct testing for the new coronavirus.... The CDC is working closely with the states to correct the issues in the testing kits, Messonnier said. The BBC link is about the WHO test, says no one knows what is going on but gives multiple possible explanations: One possible explanation is the tests are accurate and the patients do not have coronavirus at the time of testing Alternatively, there could be a problem with the way the tests are being conducted... There has also been some discussion about whether doctors testing the back of the throat are looking in the wrong place. A final option is the RT-PCR test for the new coronavirus is based on flawed science.... if there is a poor match between the primer and the virus in the patient, then an infected patient could get a negative result. The Propublica link is about the CDC test: The CDC designed a flawed test for COVID-19, then took weeks to figure out a fix so state and local labs could use it.

lonelappde 7y ago
Don't use indentation for blockquotes. HN uses indentation for non-wrapped lines non-proportional font. Use > or " or * > One possible explanation is the tests are accurate and the patients do not have coronavirus at the time of testing > Alternatively, there could be a problem with the way the tests are being conducted... There has also been some discussion about whether doctors testing the back of the throat are looking in the wrong place. > A final option is the RT-PCR test for the new coronavirus is based on flawed science.... if there is a poor match between the primer and the virus in the patient, then an infected patient could get a negative result.

joe_the_user 7y ago

1) China and Korea have effectively treated the virus, infections in both those areas have been declining. And Korea now is effectively the lowest fatality rate for any of the effected countries which points to excellent surveillance and treatment. I darn well intent to keep pointing to this. 2) Some article point to the main vector in Italy being patient left in a hospital for 36 hour before being diagnosed and treated. This allowed the disease to spread in the community where testing was not being done - kind of like the US. 3) The Chinese test may indeed might have had problems at various points (your first link is rather anecdotal, hardly proves the test was a "coin flip". Other posters note your links don't back your arguments). The American test had even more problems and still hasn't ramped up to strong production. Making tests is hard, it seems. The CDC's "your test has problems and we know we can do better" attitude looks misguided in retrospect. 4) It seems like you're doing a bunch of speculation with little evidence. I suggest you look at infection and mortality as a basis for thinking about what country is doing well or badly. [1] [1] https://covid19info.live/ https://covid19info.live/

lern_too_spel 7y ago
> And Korea now is effectively the lowest fatality rate for any of the effected countries which points to excellent surveillance and treatment. I darn well intent to keep pointing to this. That's misleading. Korea has the highest active case ratio of any of the hardest hit countries. The flip side of the lowest CFR coin is that Korea also has by far the lowest recovery rate of any of those countries. You need to wait for the active cases to turn into deaths or recoveries. From JHU CSSE: South Korea Confirmed: 7,382 Deaths: 50 Recovered: 118 Existing: 7,214 If you're just looking at recovery rate (also misleading), Iran seems much better than Korea: Iran Confirmed: 6,566 Deaths: 194 Recovered: 2,134 Existing: 4,238
- joe_the_user 7y ago
  I don't know what the criteria for recovery is. My impression is there isn't much of a international standard and so the inter-country comparisons aren't that useful. Iran might have a higher recovery rate but that might be more an artifact of how they measure this. In all other measure, South Korea is doing well. Avoiding death is much unambiguous a measure. Edit: Yes, because Korea has experienced an exponential increase in cases, most cases in Korea are "new" but this is true for most other countries - though countries where they only find cases by people dying might be different but not in a good way. Edit2: Also, it is true that Korea's lower mortality is likely partly a product of Korea's widely testing and finding asymptomatic carriers. But this is also a good thing since it allows Korea to get these people to quarantine and lower the transmission rate, hence the declining rate of infection there.

cma 7y ago

I believe they run the tests multiple times and get more accuracy from the repeated runs.