4 ms·

Most of what I've seen suggests that at time of positive test results, 40% to 70% of people have not experienced symptoms. Have you seen numbers very different

Most of what I've seen suggests that at time of positive test results, 40% to 70% of people have not experienced symptoms. Have you seen numbers very different from that? [Edit: 'No symptoms experienced at time of positive test results' is intended to mean the same as 'no symptoms experienced yet at time of positive test results'.]

crdrost 7y ago
That can't be true for the official confirmed numbers. Like, it was for a while impossible to get a test if you are not experiencing multiple symptoms AND can make a case that you might have been exposed via interacting with someone who has traveled. Even now I don't think they're giving the test if you don't have a fever. It's implausible that 50% of the people tested by the official pathway had no symptoms because the official pathway is not available when you have no symptoms. But if you mean that you've seen a 50% "asymptomatic transmission" rate, in other words studies like this that purport to test a bunch of people at random and see how many of them have COVID-19, note that this definition of "asymptomatic" may include many with symptoms not severe enough to be hospitalized -- in other words they might have been feverish and coughing but not moreso than a typical cold. I myself have had a really nasty cough but it is not "dry" but "productive" and it has not come with a fever -- I would really love to be tested but right now that does not seem to be possible! Maybe I am in this above grouping of "asymptomatic" folks. The OP article suggests that as many as 98-99% of cases might not involve hospitalization and therefore might be cases like mine (assuming I do indeed have COVID-19, maybe I don't). Now it is likely that there is some sort of selection bias in how they recruited candidates, but still it tends to push that number above your high end of 70%, suggesting maybe it's closer to 80 or 90%. On the other hand while the paper says that it did its due diligence subtracting out the test's false-positive rate, a rather small error here can have a big impact on that number because there are so few true positives right now. In some ways the paper's claim is a bit of good news, it means that this disease has much lower mortality than we were originally told. (There may be lower bounds on mortality -- I have heard of one town in Italy where 1% of its population is gone due to COVID-19 in which case that would seem to be a good lower bound.) In other ways it is bad news, it means that this disease, still with nontrivial mortality, is going to be much less affected by quarantine countermeasures and the social distancing stuff is really the only reason it is spreading as slowly as it is, so that we need to endure the pain of isolation for much longer -- potentially until testing becomes widespread and cheap. That may not be too much longer, as mentioned in a previous HN comment/story [1] that if you can get testing to work with the old Sanger sequencers used in the Human Genome Project you can maybe ramp up to 200,000 samples/day at first with possibilities to go up to 1M/day once you solve additional logistical problems. Before that the production of kits and sourcing of reagents may be your limit. [1] https://news.ycombinator.com/item?id=22808208 https://news.ycombinator.com/item?id=22808208
- tom-thistime 7y ago
  Ok, we can't conclude anything about the rate of symptoms from testing that was only conducted on people showing severe symptoms. I don't think we can conclude much of anything from the OP either, because its rate of positives seems compatible with the rate of false positives from the test. They could have 0% infected, they could have 5% infected. An example where testing was conducted without requiring symptoms first: https://taskandpurpose.com/news/uss-theodore-roosevelt-sailors-coronavirus-asymptomatic https://taskandpurpose.com/news/uss-theodore-roosevelt-sailo...
  - wool_gather 7y ago
    Yes, although note that it's not clear which kind of test is being used by the Navy there. If it's the nasal swab-PCR test that most civilians are getting, then the claim of "asymptomatic" must be accompanied by a "yet". We can't really conclude anything for at least two weeks after the positive result -- after seeing whether those people ever develop symptoms. If it's blood-antibody testing, then we can give the statement a little more weight, because a positive result would mean the infection is in a later stage or even past. I have no idea whether the Navy is using these tests.
  - jboy55 7y ago
    Also, they weren't able to factor out a bias towards people seeking confirmation tests due to perceived COVID symptoms. This is in the bay area, where people were very quick to self-quarantine. Most people have been working from home since early March. They were asking people to break their self-quarantine to get tested without having any symptoms?
kaikai 7y ago
Have not experienced symptoms yet. I haven't seen any information about testing people and then following through until a negative test, to see whether they stay asymptomatic. It's more likely that we're testing them in the window between being infected and showing symptoms.
- lmlsna 7y ago
  Confirmed population infection rate in Santa Clara is like 0.1%, and has been on a stay at home order for a month. Highly unlikely these are all just people who have produced antibodies as part of a yet-to-be overrun immune response.

crdrost 7y ago

That can't be true for the official confirmed numbers. Like, it was for a while impossible to get a test if you are not experiencing multiple symptoms AND can make a case that you might have been exposed via interacting with someone who has traveled. Even now I don't think they're giving the test if you don't have a fever. It's implausible that 50% of the people tested by the official pathway had no symptoms because the official pathway is not available when you have no symptoms. But if you mean that you've seen a 50% "asymptomatic transmission" rate, in other words studies like this that purport to test a bunch of people at random and see how many of them have COVID-19, note that this definition of "asymptomatic" may include many with symptoms not severe enough to be hospitalized -- in other words they might have been feverish and coughing but not moreso than a typical cold. I myself have had a really nasty cough but it is not "dry" but "productive" and it has not come with a fever -- I would really love to be tested but right now that does not seem to be possible! Maybe I am in this above grouping of "asymptomatic" folks. The OP article suggests that as many as 98-99% of cases might not involve hospitalization and therefore might be cases like mine (assuming I do indeed have COVID-19, maybe I don't). Now it is likely that there is some sort of selection bias in how they recruited candidates, but still it tends to push that number above your high end of 70%, suggesting maybe it's closer to 80 or 90%. On the other hand while the paper says that it did its due diligence subtracting out the test's false-positive rate, a rather small error here can have a big impact on that number because there are so few true positives right now. In some ways the paper's claim is a bit of good news, it means that this disease has much lower mortality than we were originally told. (There may be lower bounds on mortality -- I have heard of one town in Italy where 1% of its population is gone due to COVID-19 in which case that would seem to be a good lower bound.) In other ways it is bad news, it means that this disease, still with nontrivial mortality, is going to be much less affected by quarantine countermeasures and the social distancing stuff is really the only reason it is spreading as slowly as it is, so that we need to endure the pain of isolation for much longer -- potentially until testing becomes widespread and cheap. That may not be too much longer, as mentioned in a previous HN comment/story [1] that if you can get testing to work with the old Sanger sequencers used in the Human Genome Project you can maybe ramp up to 200,000 samples/day at first with possibilities to go up to 1M/day once you solve additional logistical problems. Before that the production of kits and sourcing of reagents may be your limit. [1] https://news.ycombinator.com/item?id=22808208 https://news.ycombinator.com/item?id=22808208

tom-thistime 7y ago
Ok, we can't conclude anything about the rate of symptoms from testing that was only conducted on people showing severe symptoms. I don't think we can conclude much of anything from the OP either, because its rate of positives seems compatible with the rate of false positives from the test. They could have 0% infected, they could have 5% infected. An example where testing was conducted without requiring symptoms first: https://taskandpurpose.com/news/uss-theodore-roosevelt-sailors-coronavirus-asymptomatic https://taskandpurpose.com/news/uss-theodore-roosevelt-sailo...
- wool_gather 7y ago
  Yes, although note that it's not clear which kind of test is being used by the Navy there. If it's the nasal swab-PCR test that most civilians are getting, then the claim of "asymptomatic" must be accompanied by a "yet". We can't really conclude anything for at least two weeks after the positive result -- after seeing whether those people ever develop symptoms. If it's blood-antibody testing, then we can give the statement a little more weight, because a positive result would mean the infection is in a later stage or even past. I have no idea whether the Navy is using these tests.
- jboy55 7y ago
  Also, they weren't able to factor out a bias towards people seeking confirmation tests due to perceived COVID symptoms. This is in the bay area, where people were very quick to self-quarantine. Most people have been working from home since early March. They were asking people to break their self-quarantine to get tested without having any symptoms?

kaikai 7y ago

Have not experienced symptoms yet. I haven't seen any information about testing people and then following through until a negative test, to see whether they stay asymptomatic. It's more likely that we're testing them in the window between being infected and showing symptoms.

lmlsna 7y ago
Confirmed population infection rate in Santa Clara is like 0.1%, and has been on a stay at home order for a month. Highly unlikely these are all just people who have produced antibodies as part of a yet-to-be overrun immune response.