6 ms·

Like a lot of the Chinese solutions to Covid-19, this is interesting because it really shouldn't work. We know that these kinds of swab tests have a fairly subs

by makomk 6y ago

Like a lot of the Chinese solutions to Covid-19, this is interesting because it really shouldn't work. We know that these kinds of swab tests have a fairly substantial false negative rate - initially from Chinese research, and then I think confirmed pretty much everywhere else - especially when trying to detect pre-symptomatic carriers of the disease. (Also, based on other results elsewhere, I think we'd expect to see a few people out of a Wuhan-sized outbreak testing positive even if they'd long since recovered from the disease and were no longer infectious.)

jquery 6y ago
> Like a lot of the Chinese solutions to Covid-19, this is interesting because it really shouldn't work. Are you suggesting China is putting out propaganda?
simonh 6y ago
Antibody tests like this are very limited. They only detect positive after you've had the virus for several days and they have a significant false negative rate. They are very poor at identifying if this person right here has the virus. However if what you're doing is trying to assess the prevalence of the virus in a population of hundreds of thousands, or millions, they could be very useful. They will help identify clusters of infection so you can then use the PCR test on known associates to pinpoint cases. I think this is what the Chinese government did in Beijing, they used mass antibody testing, but PCR testing of everyone in the food market where they knew there were cases.
- nelaboras 6y ago
  You test as much as possible and for any positive you ask the candidate and all associates to self-isolate. Maybe X who is infected gives you a false negative, but if you also test X's mother, husband and son you are likely to get a positive and just isolate the whole household. Similarly a false positive just means you isolate one for no reason - no harm to the community.
- James_Henry 6y ago
  I think that the commenter you are responding to is not talking about antibody tests but rather rt-pcr test (swab tests) as have been used in China.
James_Henry 6y ago
Even with a fairly substantial false negative rate, mass testing is incredibly effective for a disease that is contagious while you are asymptomatic. Suppose the test only caught half of the asymptomatic cases and that anyone with symptoms was properly self quarantining. Then you would stop the spread of the disease by half! and if you had an R0 of 2, then you'd half it to 1. Obviously, reality isn't as simple as this. It could be thought that these tests have false negatives when the viral load isn't high and when people are less contagious. The fact that the US hasn't used antigen tests on every person in the country or at least in communities with high amounts of spread should be considered one of the great scandals of our day. A great article on the subject, https://www.theatlantic.com/health/archive/2020/08/how-to-test-every-american-for-covid-19-every-day/615217/ https://www.theatlantic.com/health/archive/2020/08/how-to-te... Also, the fact that we don't do mass pooled tests in communities at the beginning of an outbreak like they did in the Xinfadi and later Wuhan outbreaks is also disappointing. We could have had this under control by now.
- swiley 6y ago
  No. I don’t want to live in a country where the government can force people to have any kind of test. It’s one thing to have misconceptions about vaccines and tests but government mandated medical treatment is totally different and completely unacceptable.
  - fragmede 6y ago
    It's a little bit more nuanced than that, since vaccines are mandatory in the US. The US government can't force kids to be vaccinated, but it can require that children attending public school be vaccinated. Which seems reasonable - if you want to use public resources, you have to be part of society, which includes protecting other people in the society with you. Most places with a society operate the same way, to different degree, and the only choice is either to opt out and live out in the wilderness, or find individuals who share your stance on, eg, vaccines.
    - jquery 6y ago
jdietrich 6y ago
China did a lot of things beside testing. Extremely strict lockdowns in affected areas, a near-total shutdown of passenger transport to and from affected regions and very rapid contact tracing. China isn't a unique outlier in this respect - South Korea and Singapore followed a similar strategy and got similar results. New Zealand faced a different set of circumstances and used a somewhat different strategy, but they're down to about a dozen cases per day.
bigpumpkin 6y ago
One feature that is overlooked from the Chinese response is the rapid contact tracing on a community level through the communist party's Neighborhood Committee. This could be duplicated in the west without authoritarianism through more effective community engagement. For more information, read this article by a New Yorker journalist: https://www.newyorker.com/magazine/2020/08/17/how-china-controlled-the-coronavirus https://www.newyorker.com/magazine/2020/08/17/how-china-cont...
- FooBarWidget 6y ago
  Yep. When I was in China in January, a person from the neighborhood committee called us and asked us whether we've been in contact with anyone from Wuhan, or whether we have any symptoms. Very simple, but contributes to tracing. In contrast, when I went back to the Netherlands 2 weeks later, nobody asked me anything. Even after I called the public health service, they told me I couldn't even voluntarily get tested even if I wanted to. Two months later, COVID-19 cases in the Netherlands surged sky-high.
taeric 6y ago
This has been one of my largest mental blocks on all of this. Per the main reports we see about how this can spread, it feels like that nothing that has worked, should have worked. Such that I'm sceptical of pretty much all coverage on this now. And I don't think that is a healthy thing to be. :(

by makomk 6y ago

jquery 6y ago

> Like a lot of the Chinese solutions to Covid-19, this is interesting because it really shouldn't work. Are you suggesting China is putting out propaganda?

simonh 6y ago

Antibody tests like this are very limited. They only detect positive after you've had the virus for several days and they have a significant false negative rate. They are very poor at identifying if this person right here has the virus. However if what you're doing is trying to assess the prevalence of the virus in a population of hundreds of thousands, or millions, they could be very useful. They will help identify clusters of infection so you can then use the PCR test on known associates to pinpoint cases. I think this is what the Chinese government did in Beijing, they used mass antibody testing, but PCR testing of everyone in the food market where they knew there were cases.

nelaboras 6y ago
You test as much as possible and for any positive you ask the candidate and all associates to self-isolate. Maybe X who is infected gives you a false negative, but if you also test X's mother, husband and son you are likely to get a positive and just isolate the whole household. Similarly a false positive just means you isolate one for no reason - no harm to the community.
James_Henry 6y ago
I think that the commenter you are responding to is not talking about antibody tests but rather rt-pcr test (swab tests) as have been used in China.

James_Henry 6y ago

Even with a fairly substantial false negative rate, mass testing is incredibly effective for a disease that is contagious while you are asymptomatic. Suppose the test only caught half of the asymptomatic cases and that anyone with symptoms was properly self quarantining. Then you would stop the spread of the disease by half! and if you had an R0 of 2, then you'd half it to 1. Obviously, reality isn't as simple as this. It could be thought that these tests have false negatives when the viral load isn't high and when people are less contagious. The fact that the US hasn't used antigen tests on every person in the country or at least in communities with high amounts of spread should be considered one of the great scandals of our day. A great article on the subject, https://www.theatlantic.com/health/archive/2020/08/how-to-test-every-american-for-covid-19-every-day/615217/ https://www.theatlantic.com/health/archive/2020/08/how-to-te... Also, the fact that we don't do mass pooled tests in communities at the beginning of an outbreak like they did in the Xinfadi and later Wuhan outbreaks is also disappointing. We could have had this under control by now.

swiley 6y ago
No. I don’t want to live in a country where the government can force people to have any kind of test. It’s one thing to have misconceptions about vaccines and tests but government mandated medical treatment is totally different and completely unacceptable.
- fragmede 6y ago
  It's a little bit more nuanced than that, since vaccines are mandatory in the US. The US government can't force kids to be vaccinated, but it can require that children attending public school be vaccinated. Which seems reasonable - if you want to use public resources, you have to be part of society, which includes protecting other people in the society with you. Most places with a society operate the same way, to different degree, and the only choice is either to opt out and live out in the wilderness, or find individuals who share your stance on, eg, vaccines.
  - jquery 6y ago

jdietrich 6y ago

China did a lot of things beside testing. Extremely strict lockdowns in affected areas, a near-total shutdown of passenger transport to and from affected regions and very rapid contact tracing. China isn't a unique outlier in this respect - South Korea and Singapore followed a similar strategy and got similar results. New Zealand faced a different set of circumstances and used a somewhat different strategy, but they're down to about a dozen cases per day.

bigpumpkin 6y ago

One feature that is overlooked from the Chinese response is the rapid contact tracing on a community level through the communist party's Neighborhood Committee. This could be duplicated in the west without authoritarianism through more effective community engagement. For more information, read this article by a New Yorker journalist: https://www.newyorker.com/magazine/2020/08/17/how-china-controlled-the-coronavirus https://www.newyorker.com/magazine/2020/08/17/how-china-cont...

FooBarWidget 6y ago
Yep. When I was in China in January, a person from the neighborhood committee called us and asked us whether we've been in contact with anyone from Wuhan, or whether we have any symptoms. Very simple, but contributes to tracing. In contrast, when I went back to the Netherlands 2 weeks later, nobody asked me anything. Even after I called the public health service, they told me I couldn't even voluntarily get tested even if I wanted to. Two months later, COVID-19 cases in the Netherlands surged sky-high.

taeric 6y ago

This has been one of my largest mental blocks on all of this. Per the main reports we see about how this can spread, it feels like that nothing that has worked, should have worked. Such that I'm sceptical of pretty much all coverage on this now. And I don't think that is a healthy thing to be. :(