7 ms·

When can we test everyone?

52 points by jeremyw 6y ago

klipt 6y ago
Why would you want to test "everyone"? For epidemiological purposes, you only need a statistically valid sample, which is much smaller than "everyone". For medical purposes, you only need to test people who are sick, which is hopefully also much smaller than "everyone".
- ketamine__ 6y ago
  Asymptomatic carriers of the virus can self-isolate. Contact tracing can be done at that point as well.
- poidos 6y ago
  Aren’t asymptomatic carriers a big part of the problem? That is, it seems like testing everyone (instead of just testing folks that are sick) enables us to find asymptomatic carriers and isolate them much sooner than (if) they start showing symptoms.
- maxerickson 6y ago
  The idea is that testing everyone who has a fair chance of being infections makes suppression more effective. If the goal is to just have everyone get it, but over a longer period of time, it doesn't matter a lot. But that's a shitty goal.
  - didericis 6y ago
    This level of isolation can’t be sustained for the year or so it’s going to take until a vaccine is created. Testing for active infections will help identify people who should self isolate to slow the spread, which is good, but we also should be determining who has antibodies and is able to end self isolation. We need to release some of the social pressure building up and allow people who are ok to go out again to do so.
- BurningFrog 6y ago
  You absolutely need to get infected people without symptoms out of infecting people! They don't "get sick", so testing is the only way. That seems to be the main way this is spreading.
- alistairSH 6y ago
  For medical purposes, you don't even need to test the sick. We don't have treatments available at this time, so the course of treatment doesn't current vary. IE, if you have COVID-like symptoms and are moved to the ICU, the course of treatment is the same with or without a positive test. I've seen it argued that instead of testing the sick (as we currently do), we should be testing individuals who are "high touch" and likely to infect others (even lacking symptoms). Medical staff, first responders. Pharmacy and grocery employees. Bus drivers. Etc. I don't know enough to argue this is a better approach.
  - smacktoward 6y ago
    Since an infected person can be contagious for days before showing any symptoms, it'd be ideal if we could regularly test everybody, regardless of whether or not they are currently symptomatic. That way we could get them isolated early, which would prevent them from infecting X other people before they even realize they're sick, as well as cutting down on the number of contacts they've had that would need to be traced.
- lbeltrame 6y ago
  People with antibodies (assuming the test works and is specific enough) may have cleared the infection already and they may enjoy (temporary?) immunity enough for them to resume a part of their activities in a lockdown. The other goal, as others have said, is to isolate, and contact trace the infected. And I add, early detection might also help with treatment, since the scant evidence so far suggests that pharmacological interventions that target the virus might be more effective early on during the infection.
bhobs 6y ago
>everyone In the us. Nice.
- ecmascript 6y ago
  As a european I immedietly suspected this before clicking the link. Was not disappointed. This is very funny.
  - davidw 6y ago
    OTOH, most of Europe is probably ahead of the US. Italy and Germany are certainly doing a lot more tests per capita. So I guess it's not so bad...
    - RandallBrown 6y ago
      And parts of the US are ahead of Italy and Germany.
- Waterluvian 6y ago
  I'm not upset but indeed, you get reminded daily that you're not American because of sites like this.
- slap 6y ago
  I knew it would be US-specific by the website name...
jameslevy 6y ago
Are there different tests for antibodies vs. active infections? Or is it just that if you have symptoms and antibodies, that means you have an active infection? For example, many of us who want to see family, etc. at some point may want to test to make sure we're not currently contagious, even if we don't have any symptoms. If we have antibodies and no symptoms, that doesn't necessarily imply that we're not currently contagious.
- maxerickson 6y ago
  Yes, the tests are different. The tests that look for the virus are probably more accurate than the antibody tests, at least right now.
  - dba7dba 6y ago
    I have read that S. Korea's disease control center has not approved antibody tests because antibody tests are not accurate enough. Multiple S. Korean companies submitted test kits for coronavirus for approval, and not all were approved because of insufficient accuracy. Mainly antibody tests.
- smacktoward 6y ago
  Yes. To see if someone has an active infection, you want an antigen test. To see if someone had an active infection in the past, you want an antibody test. More info at https://www.cnet.com/how-to/coronavirus-testing-what-to-know-about-antibody-tests-antigens-and-serology/ https://www.cnet.com/how-to/coronavirus-testing-what-to-know...
- didericis 6y ago
  Yes, there are two types of tests. PCR tests check for active infections, whereas antibody tests check for immunity (For that strain of the virus at least). Antibody tests are only just starting to be done now, and not on a wide scale. It is currently unknown how long the antibodies last, but having antibodies does not mean you have an active infection. Info sourced from here: https://youtu.be/kgzFAdYwYLM https://youtu.be/kgzFAdYwYLM
nostromo 6y ago
What we need now is antibody testing, not testing for Covid-19. All the antibody studies in the US so far are showing that antibodies are present in at least an order of magnitude greater number of people than the official number of people with Covid-19. This has huge implications for our response. Given this new data, LA is suggesting [1] that ~5% of the population of LA has already developed antibodies, which would mean the fatality rate may be as low as 0.10-0.20%. (For comparison, the seasonal flu is 0.05%-0.10%.) Knowing if this is really the case for the entire nation would have huge implications for our response. 1. https://www.facebook.com/countyofla/videos/537241533852930/ https://www.facebook.com/countyofla/videos/537241533852930/
- faitswulff 6y ago
  Additionally, we need to find out how long antibodies confer immunity for.
- bosswipe 6y ago
  Those LA and Santa Clara studies have come under intense criticism. From other data it looks like the number is closer to .5% than .1%.
  - jonny_eh 6y ago
    Which is still a far cry from the 4% mortality rate predicted in March.
    - bosswipe 6y ago
      As more data comes in the estimates will continue to be refined.
    - ggreer 6y ago
      What prominent institutions or figures were claiming a 4% IFR in March? They may have been saying that for case fatality rates, but not infections.
- gnulinux 6y ago
ltbarcly3 6y ago
Testing is only really useful for a handful of things: - Identifying people who are carriers so they can be isolated - Contact tracing (pointless at the moment, there are hundreds of thousands of people in the US who are infected) - Ruling out other diseases or conditions that are treatable Testing basically doesn't help anyone who has covid, it helps the people they would have spread it to if you can prevent that spread. There is no treatment for covid whatsoever, knowing you have it doesn't help you live longer or become healthy sooner. Knowing you don't have it, if you are already sick, might help if that lets them invest in further testing or treatments for other, non-covid, conditions. Testing is easy to point at, but at the moment more testing would have limited impact. Even if we were to test everyone in the US, it would have to be done in a relatively short window of time to allow for a significant impact, and it's unlikely that there will be enough testing capacity to use this strategy before we reach saturation levels of infection. If they test me today and I'm negative, then they test you in 6 weeks, what does that get you and me? I was very likely infected in the meantime. This could be used socially like an negative AIDS test, except instead of a few months or years the validity of a test as a social currency is about a week, making it more or less useless as a way to avoid being infected.
- didericis 6y ago
  The biggest benefit would come from antibody testing. If we could end social isolation for people who have antibodies, which is probably a very large number of people, that’d be a big win.
  - ltbarcly3 6y ago
    I agree, once they have data to support that antibodies prevent reinfection at a level that would be contagious.
    - didericis 6y ago
      That data currently exists, although I’m not sure how definitive it is. A study was conducted where infected monkeys were exposed, which triggered detectable antibodies, and then exposed again. The monkeys did not show signs of the virus upon secondary exposure. I believe the biggest open question is the longevity of those antibodies and whether or not the virus mutates rapidly enough to eventually make the antibodies ineffective. Information comes from this video: https://youtu.be/kgzFAdYwYLM https://youtu.be/kgzFAdYwYLM
ttcbj 6y ago
FWIW, I think this is a useful idea. But I think it would be more helpful if you clearly explained why you choose those stats and rethought what you are trying to say. I personally care about "When can I feel safe going out?" Testing is just a means to that end. * I would lead with the % of the population tested (not the total) and make it in the last 7 days, since I really care how likely they are to detect a current outbreak. * I think to be really useful, it needs to be localized by county, since what I really care about is how likely I am to get infected, and that means I are about testing in my area. * I would go with the positive rate in the last 7 days. It's important to explain that a high positive rate indicates they are probably only testing people with symptoms, and so they are probably missing lots of infectious asymptomatic cases. * Then, I think I would drop the recent growth rate in testing, because I suspect that the growth rate is not going to grow consistently, and also that testing growth will be unevenly distributed. I am skeptical that it is meaningful to try to predict when testing will achieve specific milestones.
JohnTHaller 6y ago
We don't have anywhere near enough tests. We also don't know how many tests are actually available or will become available as the administration has repeatedly thrown out incorrect numbers without coming anywhere close to them.

52 points by jeremyw 6y ago

Why would you want to test "everyone"? For epidemiological purposes, you only need a statistically valid sample, which is much smaller than "everyone". For medical purposes, you only need to test people who are sick, which is hopefully also much smaller than "everyone".

ketamine__ 6y ago
Asymptomatic carriers of the virus can self-isolate. Contact tracing can be done at that point as well.
poidos 6y ago
Aren’t asymptomatic carriers a big part of the problem? That is, it seems like testing everyone (instead of just testing folks that are sick) enables us to find asymptomatic carriers and isolate them much sooner than (if) they start showing symptoms.
maxerickson 6y ago
The idea is that testing everyone who has a fair chance of being infections makes suppression more effective. If the goal is to just have everyone get it, but over a longer period of time, it doesn't matter a lot. But that's a shitty goal.
- didericis 6y ago
  This level of isolation can’t be sustained for the year or so it’s going to take until a vaccine is created. Testing for active infections will help identify people who should self isolate to slow the spread, which is good, but we also should be determining who has antibodies and is able to end self isolation. We need to release some of the social pressure building up and allow people who are ok to go out again to do so.
BurningFrog 6y ago
You absolutely need to get infected people without symptoms out of infecting people! They don't "get sick", so testing is the only way. That seems to be the main way this is spreading.
alistairSH 6y ago
For medical purposes, you don't even need to test the sick. We don't have treatments available at this time, so the course of treatment doesn't current vary. IE, if you have COVID-like symptoms and are moved to the ICU, the course of treatment is the same with or without a positive test. I've seen it argued that instead of testing the sick (as we currently do), we should be testing individuals who are "high touch" and likely to infect others (even lacking symptoms). Medical staff, first responders. Pharmacy and grocery employees. Bus drivers. Etc. I don't know enough to argue this is a better approach.
- smacktoward 6y ago
  Since an infected person can be contagious for days before showing any symptoms, it'd be ideal if we could regularly test everybody, regardless of whether or not they are currently symptomatic. That way we could get them isolated early, which would prevent them from infecting X other people before they even realize they're sick, as well as cutting down on the number of contacts they've had that would need to be traced.
lbeltrame 6y ago
People with antibodies (assuming the test works and is specific enough) may have cleared the infection already and they may enjoy (temporary?) immunity enough for them to resume a part of their activities in a lockdown. The other goal, as others have said, is to isolate, and contact trace the infected. And I add, early detection might also help with treatment, since the scant evidence so far suggests that pharmacological interventions that target the virus might be more effective early on during the infection.

bhobs 6y ago

>everyone In the us. Nice.

ecmascript 6y ago
As a european I immedietly suspected this before clicking the link. Was not disappointed. This is very funny.
- davidw 6y ago
  OTOH, most of Europe is probably ahead of the US. Italy and Germany are certainly doing a lot more tests per capita. So I guess it's not so bad...
  - RandallBrown 6y ago
    And parts of the US are ahead of Italy and Germany.
Waterluvian 6y ago
I'm not upset but indeed, you get reminded daily that you're not American because of sites like this.
slap 6y ago
I knew it would be US-specific by the website name...

jameslevy 6y ago

Are there different tests for antibodies vs. active infections? Or is it just that if you have symptoms and antibodies, that means you have an active infection? For example, many of us who want to see family, etc. at some point may want to test to make sure we're not currently contagious, even if we don't have any symptoms. If we have antibodies and no symptoms, that doesn't necessarily imply that we're not currently contagious.

maxerickson 6y ago
Yes, the tests are different. The tests that look for the virus are probably more accurate than the antibody tests, at least right now.
- dba7dba 6y ago
  I have read that S. Korea's disease control center has not approved antibody tests because antibody tests are not accurate enough. Multiple S. Korean companies submitted test kits for coronavirus for approval, and not all were approved because of insufficient accuracy. Mainly antibody tests.
smacktoward 6y ago
Yes. To see if someone has an active infection, you want an antigen test. To see if someone had an active infection in the past, you want an antibody test. More info at https://www.cnet.com/how-to/coronavirus-testing-what-to-know-about-antibody-tests-antigens-and-serology/ https://www.cnet.com/how-to/coronavirus-testing-what-to-know...
didericis 6y ago
Yes, there are two types of tests. PCR tests check for active infections, whereas antibody tests check for immunity (For that strain of the virus at least). Antibody tests are only just starting to be done now, and not on a wide scale. It is currently unknown how long the antibodies last, but having antibodies does not mean you have an active infection. Info sourced from here: https://youtu.be/kgzFAdYwYLM https://youtu.be/kgzFAdYwYLM

nostromo 6y ago

What we need now is antibody testing, not testing for Covid-19. All the antibody studies in the US so far are showing that antibodies are present in at least an order of magnitude greater number of people than the official number of people with Covid-19. This has huge implications for our response. Given this new data, LA is suggesting [1] that ~5% of the population of LA has already developed antibodies, which would mean the fatality rate may be as low as 0.10-0.20%. (For comparison, the seasonal flu is 0.05%-0.10%.) Knowing if this is really the case for the entire nation would have huge implications for our response. 1. https://www.facebook.com/countyofla/videos/537241533852930/ https://www.facebook.com/countyofla/videos/537241533852930/

faitswulff 6y ago
Additionally, we need to find out how long antibodies confer immunity for.
bosswipe 6y ago
Those LA and Santa Clara studies have come under intense criticism. From other data it looks like the number is closer to .5% than .1%.
- jonny_eh 6y ago
  Which is still a far cry from the 4% mortality rate predicted in March.
  - bosswipe 6y ago
    As more data comes in the estimates will continue to be refined.
  - ggreer 6y ago
    What prominent institutions or figures were claiming a 4% IFR in March? They may have been saying that for case fatality rates, but not infections.
gnulinux 6y ago

ltbarcly3 6y ago

Testing is only really useful for a handful of things: - Identifying people who are carriers so they can be isolated - Contact tracing (pointless at the moment, there are hundreds of thousands of people in the US who are infected) - Ruling out other diseases or conditions that are treatable Testing basically doesn't help anyone who has covid, it helps the people they would have spread it to if you can prevent that spread. There is no treatment for covid whatsoever, knowing you have it doesn't help you live longer or become healthy sooner. Knowing you don't have it, if you are already sick, might help if that lets them invest in further testing or treatments for other, non-covid, conditions. Testing is easy to point at, but at the moment more testing would have limited impact. Even if we were to test everyone in the US, it would have to be done in a relatively short window of time to allow for a significant impact, and it's unlikely that there will be enough testing capacity to use this strategy before we reach saturation levels of infection. If they test me today and I'm negative, then they test you in 6 weeks, what does that get you and me? I was very likely infected in the meantime. This could be used socially like an negative AIDS test, except instead of a few months or years the validity of a test as a social currency is about a week, making it more or less useless as a way to avoid being infected.

didericis 6y ago
The biggest benefit would come from antibody testing. If we could end social isolation for people who have antibodies, which is probably a very large number of people, that’d be a big win.
- ltbarcly3 6y ago
  I agree, once they have data to support that antibodies prevent reinfection at a level that would be contagious.
  - didericis 6y ago
    That data currently exists, although I’m not sure how definitive it is. A study was conducted where infected monkeys were exposed, which triggered detectable antibodies, and then exposed again. The monkeys did not show signs of the virus upon secondary exposure. I believe the biggest open question is the longevity of those antibodies and whether or not the virus mutates rapidly enough to eventually make the antibodies ineffective. Information comes from this video: https://youtu.be/kgzFAdYwYLM https://youtu.be/kgzFAdYwYLM

ttcbj 6y ago

FWIW, I think this is a useful idea. But I think it would be more helpful if you clearly explained why you choose those stats and rethought what you are trying to say. I personally care about "When can I feel safe going out?" Testing is just a means to that end. * I would lead with the % of the population tested (not the total) and make it in the last 7 days, since I really care how likely they are to detect a current outbreak. * I think to be really useful, it needs to be localized by county, since what I really care about is how likely I am to get infected, and that means I are about testing in my area. * I would go with the positive rate in the last 7 days. It's important to explain that a high positive rate indicates they are probably only testing people with symptoms, and so they are probably missing lots of infectious asymptomatic cases. * Then, I think I would drop the recent growth rate in testing, because I suspect that the growth rate is not going to grow consistently, and also that testing growth will be unevenly distributed. I am skeptical that it is meaningful to try to predict when testing will achieve specific milestones.

JohnTHaller 6y ago

We don't have anywhere near enough tests. We also don't know how many tests are actually available or will become available as the administration has repeatedly thrown out incorrect numbers without coming anywhere close to them.