7 ms·

> For every confirmed case of COVID-19, there are likely another five to 10 people with undetected infections. I wish this was reflected more in the numbers be

> For every confirmed case of COVID-19, there are likely another five to 10 people with undetected infections. I wish this was reflected more in the numbers being presented by various authorities. There is just too much confidence that confirmed cases are representative of the spread of the virus. This unknown denominator can change mortality rate, and severe case rate by orders of magnitude. Because of the dearth of testing in the US, it seems highly likely that far more people are infected, and maybe even recovered. I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado. By the time I am able to get tested it seems likely that I won't be shedding the virus any longer, and will test negative. This article captures my feelings on this very well: https://blog.longnow.org/02020/03/14/an-epidemic-of-false-confidence-related-to-covid-19/ https://blog.longnow.org/02020/03/14/an-epidemic-of-false-co...

david_draco 7y ago
From the number of deaths you can crudely infer the number of infected, assuming the mortality on the Diamond princess and in South Korea (1%). Demographic effects are in play that don't make this quite right.
- sojournerc 7y ago
  What if many of the passengers who tested negative on the Diamond Princess had it and had already recovered when they tested negative? This is considered in the article I posted.
- rubidium 7y ago
  Totally agree. That’s the number I’ve been watching most to get a sense of how many total are infected for different regions e.g. 1 death today = 50-200 people were infected 2 weeks ago.
  - bob33212 7y ago
    Then once you have 2 weeks of death data you can't get the transmission rate. Finally you could go to Seattle and sample 50k people to see how many were infected with a serology test to further refine the 1% assumption
  - tunesmith 7y ago
    Applied to US data... 21 deaths today. 14% daily increase, doubling time of 5.2 days (2 week lag; hopefully social distancing has lengthened it since then). Assuming 1% fatality, that would mean 2100 "actual" cases two weeks ago. Assume no social distancing and doubling time of 5.2 days, or say it doubled three times in two weeks and you get 16,800 cases today. But we've already got 11k confirmed cases today, and I can't believe our confirmed count has already caught up that much. I dunno, maybe that's an indication that the fatality rate is lower than 1%. Or that dying takes longer than 14 days.
- rezeroed 7y ago
  Aren't cruise ships generally an older crowd?
  - btilly 7y ago
    Cruise ships have a lot in the 40-60 range. This gives them a higher median than the general population, but a lower density of the truly old. And deaths are strongly clustered among the truly old.
  - catalogia 7y ago
    Yes, they're basically floating nursing homes doubling as casinos.
- eanzenberg 7y ago
  More than half that cruise ship was older than 60. All the deaths on the ship attributed to coronavirus were people above 70 years old. https://cmmid.github.io/topics/covid19/severity/diamond_cruise_cfr_estimates.html https://cmmid.github.io/topics/covid19/severity/diamond_crui...
- tunesmith 7y ago
  South Korea went over 1% fatality yesterday, and they're seeing a rise in numbers again... they might not be testing enough either, so natural fatality could still be lower. (Maybe they should have shut down for two weeks.)
duxup 7y ago
>There is just too much confidence that confirmed cases are representative of the spread of the virus. Is that really the case? I'm finding it to be pretty common knowledge that "confirmed cases" is simply just that.
- bproven 7y ago
  Unfortunately, that is not how a lot of people think. Wish it was. Furthermore, when you see that (larger) number it has a psychological effect of "this might be serious".
- jamesrcole 7y ago
  Another factor is that “confirmed cases” is very very frequently reported as just “cases”.
- _jal 7y ago
  If conversations with my family are any indication, yes. People see low-looking numbers and place names of faraway cities in headlines and think it isn't serious. After making them think about incubation times that starts changing, but it takes a conversation. What is common knowledge depends very much on who you're common with.
surfmike 7y ago
Hopefully serological tests will be widely available which would tell us if we’ve had it or not.
- sojournerc 7y ago
  Agreed. That's the necessary data to know when we can start rolling back the extreme measures being taken to slow the spread. We need a measure to detect herd immunity
- 1001101 7y ago
  It sounds like there are antibody tests in the offing: https://www.technologyreview.com/s/615379/antibody-test-how-widespread-coronavirus-covid-19-really-is/ https://www.technologyreview.com/s/615379/antibody-test-how-...
dorfsmay 7y ago
Is there a test, or, what are the chances that there will be a test, to check if somebody already had covid19?
- jamesrcole 7y ago
  I had been wondering this too I know of one that’s in the works https://www.sciencemag.org/news/2020/02/singapore-claims-first-use-antibody-test-track-coronavirus-infections https://www.sciencemag.org/news/2020/02/singapore-claims-fir... I have seen other talk about such tests on Twitter but it’s too difficult to find it now. Such tests seem to be called antibody tests or serological tests/assays. EDIT: this twitter thread discusses such tests https://twitter.com/nachristakis/status/1240689935557865472?s=21 https://twitter.com/nachristakis/status/1240689935557865472?...
- kire2345 7y ago
  The German virologist Christian Drosten mentioned in his daily coronavirus update that some specialized labs at least in Germany are able to do an antibody blood test. There are also some commercial antibody tests, which have some error rate and as all antibody tests can identify the virus after 7-10 days after onset of symptoms. https://www.ndr.de/nachrichten/info/15-Coronavirus-Update-Infizierte-werden-offenbar-immun,podcastcoronavirus136.html https://www.ndr.de/nachrichten/info/15-Coronavirus-Update-In...
scott_s 7y ago
A comment by Bradley Kuszmaul on that blog post gives a good reason why the scenario presented is not likely: > Given the amount of testing being done in South Korea, we can rule out that there are a lot more people currently infected than we know about. And if there were a lot more people recovered than we know about, we would have seen deaths earlier in South Korea, since South Korea started their testing earlier. I suspect there's a lot more evidence that rules out the "fast and stealthy" hypothesis.
- notahacker 7y ago
  South Korea is far from the only place COVID-19 is present, and most of the rest of the world tests barely anyone, even if they have symptoms and would like a test, either due to lack of resources or formal policies of only testing hospitalised cases. I can detect my infection, but statistics on the rate it is spreading in the UK can't. It's also pretty well established that even in symptomatic cases where testing is widespread the disease has a multi-day incubation period.
- addisonl 7y ago
  SK is the exception.
- sojournerc 7y ago
  If the people who recover after mild/minimal symptoms do so within <5days (hypothetically), but people who have severe cases take 10 days to get severe, wouldn't that account for "would have seen deaths earlier in South Korea"?
  - scott_s 7y ago
    Yes, that would. But what evidence do we have for that? I believe you're engaging in special pleading: appealing to an exception because it fits your conclusion.
- tomerico 7y ago
  The type of testing S Korea does require the Virus to be present in the body and only work in a certain window of time. Once a Serological survey is done, we’ll know the true extant.
tejohnso 7y ago
> By the time I am able to get tested it seems likely that I won't be shedding the virus any longer, and will test negative. Shouldn't the test detect antibodies that your immune system has developed?
- epmaybe 7y ago
  Yes, but I don't think the PCR test is testing for that, currently. It's looking for pieces of viral RNA that are present in your blood. Antibody serology tests aren't readily available anywhere yet. In fact, the CDC is still developing theirs.
  - epmaybe 7y ago
    Can't edit this, but to be completely correct, it's looking for viral RNA present in samples, not necessarily blood. More commonly sputum or respiratory samples when it comes to coronavirus.
- ncallaway 7y ago
  There are different kinds of testing. The current testing that's reported in the media is an antigen tests, that directly tests for the presence of the virus. Once your viral load comes down, you will test negative for the virus. Hence the reason people are declared recovered after having two negative tests in a row. A test for the presence of antibodies is a serology test. The last time I looked into it (~one week ago), serology tests were under active development, but had not been deployed anywhere in a widespread way. So, right now the testing will only tell you if you currently have the virus. Coming relatively soon are tests that will tell you if you previously had the virus.
- thu2111 7y ago
  That sort of test is in development but isn't reliable enough for use yet. The tests currently in use detect virus DNA, not antibodies.
hinkley 7y ago
It doesn’t get called out, but when I read about the Spanish Flu I can’t help but feel that certain genotypes got very strong selective pressure. Conversely, there are probably genotypes running around today that are completely asymptomatic to Covid. You could have whole families shedding virus wherever they go and never even know what they’ve done. And one of the ways we learn about immunology is to study people who are immune or asymptomatic, so it’s not just about quarantining people that we need to identify infected individuals.
- btilly 7y ago
  This is absolutely correct. Quick recombination so that a beneficial gene can spread without losing genetic diversity of the population is is one of the benefits of sexual reproduction. And immune resistance to new threats is one of the top reasons why we need this capability. In fact we broadcast signatures of our immune systems in pheromones and women are attracted to the smell of men whose immune systems are different from their own. This improves the probability that the children will be resistant to a wider range of possible diseases. https://en.wikipedia.org/wiki/Body_odour_and_sexual_attraction https://en.wikipedia.org/wiki/Body_odour_and_sexual_attracti... is one of many places that you can start learning more about this topic.
anewguy9000 7y ago
you don't need to get tested the vast majority of people (even ederly) are going to have mild flu like symptoms. stay home and get better.
fspeech 7y ago
I think the term "asymptomatic" gives a wrong picture of the severity of the disease, when various authors use it to mean "testing positive before disease onset" or even outright untested due to testing criteria and availability.
dboreham 7y ago
Two things to know: 1. The current test is designed for the scenario that someone shows up to medical provider with symptoms. Test answers the question: are the symptoms caused by COVID-19?, quite reliably (negligible false positives, low false negatives). 2. The current test won't produce terribly useful data in someone without symptoms (either before, or after the illness). This is why for example certain well-known political figures saying they have been tested and cleared after potential exposure is not very meaningful. Therefore ideas like: let's randomly test the population to see how much of this is out there, and I had what I think was COVID-19, I want to be tested to confirm, are not practical. A test that can determine if someone was infected in the past is in development still.
- dueh3brhdudu 7y ago
  Number 2 is misleading, Trump got tested to quell opponents' fear mongering about his health. That doesn't make it more useful scientifically but no one thought it was happening for science anyway.
- wool_gather 7y ago
  I'm curious about the technical reasons for what you're saying. Can you say more? Is it a problem with figuring out the false negative rate for people without symptoms?
  - PeterisP 7y ago
    If you test on antigen that matches the virus, then that will return a negative result in the very beginning of infection and after recovery. If you want accurate numbers for statistics, including people who never had symptoms, you can do antibody testing on a random sample of population, that will indicate people who had the disease - but that's kind of too late for that particular location and those particular patients, that's for epidemiological studies and helping other locations. I recall reading about one such study for Covid, but I don't remember which country did it.
    - djsumdog 7y ago
3fe9a03ccd14ca5 7y ago
Not to mention it is still extremely difficult to be tested in the US. Yes, doctors can test you, but you basically can’t get a test unless you have all of the symptoms and are sick enough to need to visit the ER.
PragmaticPulp 7y ago
> I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado. I'm glad you're better. Please be careful going forward, though. You shouldn't assume you have an immunity unless you have a positive test result. Even with the strict pre-test screening that focus strictly on high probability patients, some locations are reporting very high (90%) negative test results from assumed cases. It's best to continue practicing safety cautions as if you did not have a COVID-19 infection
- mattnewton 7y ago
  We are also not 100% certain that having the virus once grants immunity. People have tested positive again after appearing to make a full recovery. While these results are probably better explained by remaining infected and becoming asymptomatic for a period then getting symptoms again, we can’t yet rule out the possibility of reinfection to my knowledge. https://www.latimes.com/world-nation/story/2020-03-13/china-japan-korea-coronavirus-reinfection-test-positive https://www.latimes.com/world-nation/story/2020-03-13/china-...
  - djsumdog 7y ago
    I've heard this before and it's the most troubling. Humans have adaptive immune systems. When our bodies first encounter a virus and a while blood cell successfully attaches too and breaks down a virus, it should either replicate or release the right activator proteins that will aid in breaking down the virus. Vaccines are all about tricking our immune system into preparing those specific antibodies before an infection occurs, so it can stop it quickly. If reinfection is true, what does that say about the nature of this virus and how difficult it is to create a vaccine? Are there other viruses that reinfect like this?
    - sojournerc 7y ago
      I've also heard it, but I think we need more data. If true, it would go against all priors for how humans build immunity to viruses - especially coronavirus (common cold). There may be a time limit to immunity, but having none at all after recovery would be rare indeed. Without significant evidence (more than one somewhat anecdotal case of re-emergence), there's little reason to assume the body doesn't "remember" the virus after recovery with antibodies. Seems like unnecessary FUD to spread that idea around without more evidence.
3JPLW 7y ago
It seems like you're pushing back on the CFR, possibly driven by trying to pessimize the need for action. In the small Italian city of Nembro in Bergamo, 0.6% of their entire population has died in the last 12 days. That's 70 people in a small town of 11,000 — typically there are fewer than 70 deaths every six months. Now we're certainly _overestimating_ the denominator and still getting a number that's larger than the flu. While the numerator is also an overestimate (because it includes deaths not related to COVID-19), their healthcare system is stretched beyond capacity due to the virus leading to difficulties treating all illnesses and traumas. https://www.washingtonpost.com/world/europe/coronavirus-obituaries-bergamo-italy/2020/03/16/6c342f02-66c7-11ea-b199-3a9799c54512_story.html https://www.washingtonpost.com/world/europe/coronavirus-obit...
- guscost 7y ago
  You should include demographic information, since it is relevant to your argument: [Nembro] Age Distribution (E 2019) 0-9 years 1,018 10-19 years 1,191 20-29 years 1,179 30-39 years 1,192 40-49 years 1,640 50-59 years 1,850 60-69 years 1,465 70-79 years 1,181 80+ years 810 > In 2010, there were 119,551 people residing in Bergamo (in which the greater area has about 500 000 inhabitants), located in the province of Bergamo, Lombardia, of whom 46.6% were male and 53.4% were female. Minors (children ages 18 and younger) totalled 16.79 percent of the population compared to pensioners who number 23.61 percent. This compares with the Italian average of 17.88 percent (minors) and 20.29 percent (pensioners). https://www.citypopulation.de/en/italy/lombardia/bergamo/016144__nembro/ https://www.citypopulation.de/en/italy/lombardia/bergamo/016... https://en.wikipedia.org/wiki/Bergamo#Demographics https://en.wikipedia.org/wiki/Bergamo#Demographics
  - 3JPLW 7y ago
    Cool, thanks for the data. Looks like their population is 30% over 60, whereas the US (for example) is 20%. Even if we assume _every_ death is someone over 60 (it's not), that'd adjust the percentage to 0.4% in a generic US town. Note that Florida is similarly 28% over 60.
    - 7y ago
BiteCode_dev 7y ago
People are mostly looking at the death count, which is still very low for a pandemic. It's hard to convince people to sacrifice so much when they look outside their windows and see nothing special, plus read the news and find that some bomb/earth quake/accident somewhere killed more people in a day than the corona virus in a month.
CydeWeys 7y ago
There is a blood serum test already available that can determine if you had coronavirus (by testing for COVID-specific antibodies produced by your body). I'd say wait until the pandemic dies down and then go get that if you're curious. There's going to be some very interesting population studies done post-pandemic to determine exactly what percentage of people had asymptomatic cases (and thus could have unknowingly been contributing to the spread).
lihaciudaniel 7y ago
>I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado Wow that really sucks, you must be the first HNer, also symptoms include fever and dry cough
naasking 7y ago
> Because of the dearth of testing in the US, it seems highly likely that far more people are infected, and maybe even recovered. It's not just highly likely, it's absolutely certain. I recommend the recent Khan academy video on this if you want to understand the math and you want a healthy dose of panic: https://www.youtube.com/watch?v=mCa0JXEwDEk https://www.youtube.com/watch?v=mCa0JXEwDEk
dboreham 7y ago
>I wish this was reflected more in the numbers being presented by various authorities. UK authorities presented this exact number at their press conference last week.
baron_harkonnen 7y ago
> This unknown denominator can change mortality rate, and severe case rate by orders of magnitude. The two best data points we have would be South Korea and the Diamond Princess cruise ship. Both of these groups have high rates of testing and both have had enough time that we can know how the most of the cases played out, and in both cases we see the death rate at about 1%. This doesn't take into account possibly different age group distributions. The cruise ship probably has less children and less 80+ people than on typical distributions. Additionally both the Diamond Princess and South Korea cases assume ready access to medical treatment. If the medical system is overwhelmed we will see much higher CFR due to critical cases not receiving adequate care.

david_draco 7y ago

From the number of deaths you can crudely infer the number of infected, assuming the mortality on the Diamond princess and in South Korea (1%). Demographic effects are in play that don't make this quite right.

sojournerc 7y ago
What if many of the passengers who tested negative on the Diamond Princess had it and had already recovered when they tested negative? This is considered in the article I posted.
rubidium 7y ago
Totally agree. That’s the number I’ve been watching most to get a sense of how many total are infected for different regions e.g. 1 death today = 50-200 people were infected 2 weeks ago.
- bob33212 7y ago
  Then once you have 2 weeks of death data you can't get the transmission rate. Finally you could go to Seattle and sample 50k people to see how many were infected with a serology test to further refine the 1% assumption
- tunesmith 7y ago
  Applied to US data... 21 deaths today. 14% daily increase, doubling time of 5.2 days (2 week lag; hopefully social distancing has lengthened it since then). Assuming 1% fatality, that would mean 2100 "actual" cases two weeks ago. Assume no social distancing and doubling time of 5.2 days, or say it doubled three times in two weeks and you get 16,800 cases today. But we've already got 11k confirmed cases today, and I can't believe our confirmed count has already caught up that much. I dunno, maybe that's an indication that the fatality rate is lower than 1%. Or that dying takes longer than 14 days.
rezeroed 7y ago
Aren't cruise ships generally an older crowd?
- btilly 7y ago
  Cruise ships have a lot in the 40-60 range. This gives them a higher median than the general population, but a lower density of the truly old. And deaths are strongly clustered among the truly old.
- catalogia 7y ago
  Yes, they're basically floating nursing homes doubling as casinos.
eanzenberg 7y ago
More than half that cruise ship was older than 60. All the deaths on the ship attributed to coronavirus were people above 70 years old. https://cmmid.github.io/topics/covid19/severity/diamond_cruise_cfr_estimates.html https://cmmid.github.io/topics/covid19/severity/diamond_crui...
tunesmith 7y ago
South Korea went over 1% fatality yesterday, and they're seeing a rise in numbers again... they might not be testing enough either, so natural fatality could still be lower. (Maybe they should have shut down for two weeks.)

duxup 7y ago

>There is just too much confidence that confirmed cases are representative of the spread of the virus. Is that really the case? I'm finding it to be pretty common knowledge that "confirmed cases" is simply just that.

bproven 7y ago
Unfortunately, that is not how a lot of people think. Wish it was. Furthermore, when you see that (larger) number it has a psychological effect of "this might be serious".
jamesrcole 7y ago
Another factor is that “confirmed cases” is very very frequently reported as just “cases”.
_jal 7y ago
If conversations with my family are any indication, yes. People see low-looking numbers and place names of faraway cities in headlines and think it isn't serious. After making them think about incubation times that starts changing, but it takes a conversation. What is common knowledge depends very much on who you're common with.

surfmike 7y ago

Hopefully serological tests will be widely available which would tell us if we’ve had it or not.

sojournerc 7y ago
Agreed. That's the necessary data to know when we can start rolling back the extreme measures being taken to slow the spread. We need a measure to detect herd immunity
1001101 7y ago
It sounds like there are antibody tests in the offing: https://www.technologyreview.com/s/615379/antibody-test-how-widespread-coronavirus-covid-19-really-is/ https://www.technologyreview.com/s/615379/antibody-test-how-...

dorfsmay 7y ago

Is there a test, or, what are the chances that there will be a test, to check if somebody already had covid19?

jamesrcole 7y ago
I had been wondering this too I know of one that’s in the works https://www.sciencemag.org/news/2020/02/singapore-claims-first-use-antibody-test-track-coronavirus-infections https://www.sciencemag.org/news/2020/02/singapore-claims-fir... I have seen other talk about such tests on Twitter but it’s too difficult to find it now. Such tests seem to be called antibody tests or serological tests/assays. EDIT: this twitter thread discusses such tests https://twitter.com/nachristakis/status/1240689935557865472?s=21 https://twitter.com/nachristakis/status/1240689935557865472?...
kire2345 7y ago
The German virologist Christian Drosten mentioned in his daily coronavirus update that some specialized labs at least in Germany are able to do an antibody blood test. There are also some commercial antibody tests, which have some error rate and as all antibody tests can identify the virus after 7-10 days after onset of symptoms. https://www.ndr.de/nachrichten/info/15-Coronavirus-Update-Infizierte-werden-offenbar-immun,podcastcoronavirus136.html https://www.ndr.de/nachrichten/info/15-Coronavirus-Update-In...

scott_s 7y ago

A comment by Bradley Kuszmaul on that blog post gives a good reason why the scenario presented is not likely: > Given the amount of testing being done in South Korea, we can rule out that there are a lot more people currently infected than we know about. And if there were a lot more people recovered than we know about, we would have seen deaths earlier in South Korea, since South Korea started their testing earlier. I suspect there's a lot more evidence that rules out the "fast and stealthy" hypothesis.

notahacker 7y ago
South Korea is far from the only place COVID-19 is present, and most of the rest of the world tests barely anyone, even if they have symptoms and would like a test, either due to lack of resources or formal policies of only testing hospitalised cases. I can detect my infection, but statistics on the rate it is spreading in the UK can't. It's also pretty well established that even in symptomatic cases where testing is widespread the disease has a multi-day incubation period.
addisonl 7y ago
SK is the exception.
sojournerc 7y ago
If the people who recover after mild/minimal symptoms do so within <5days (hypothetically), but people who have severe cases take 10 days to get severe, wouldn't that account for "would have seen deaths earlier in South Korea"?
- scott_s 7y ago
  Yes, that would. But what evidence do we have for that? I believe you're engaging in special pleading: appealing to an exception because it fits your conclusion.
tomerico 7y ago
The type of testing S Korea does require the Virus to be present in the body and only work in a certain window of time. Once a Serological survey is done, we’ll know the true extant.

tejohnso 7y ago

> By the time I am able to get tested it seems likely that I won't be shedding the virus any longer, and will test negative. Shouldn't the test detect antibodies that your immune system has developed?

epmaybe 7y ago
Yes, but I don't think the PCR test is testing for that, currently. It's looking for pieces of viral RNA that are present in your blood. Antibody serology tests aren't readily available anywhere yet. In fact, the CDC is still developing theirs.
- epmaybe 7y ago
  Can't edit this, but to be completely correct, it's looking for viral RNA present in samples, not necessarily blood. More commonly sputum or respiratory samples when it comes to coronavirus.
ncallaway 7y ago
There are different kinds of testing. The current testing that's reported in the media is an antigen tests, that directly tests for the presence of the virus. Once your viral load comes down, you will test negative for the virus. Hence the reason people are declared recovered after having two negative tests in a row. A test for the presence of antibodies is a serology test. The last time I looked into it (~one week ago), serology tests were under active development, but had not been deployed anywhere in a widespread way. So, right now the testing will only tell you if you currently have the virus. Coming relatively soon are tests that will tell you if you previously had the virus.
thu2111 7y ago
That sort of test is in development but isn't reliable enough for use yet. The tests currently in use detect virus DNA, not antibodies.

hinkley 7y ago

It doesn’t get called out, but when I read about the Spanish Flu I can’t help but feel that certain genotypes got very strong selective pressure. Conversely, there are probably genotypes running around today that are completely asymptomatic to Covid. You could have whole families shedding virus wherever they go and never even know what they’ve done. And one of the ways we learn about immunology is to study people who are immune or asymptomatic, so it’s not just about quarantining people that we need to identify infected individuals.

btilly 7y ago
This is absolutely correct. Quick recombination so that a beneficial gene can spread without losing genetic diversity of the population is is one of the benefits of sexual reproduction. And immune resistance to new threats is one of the top reasons why we need this capability. In fact we broadcast signatures of our immune systems in pheromones and women are attracted to the smell of men whose immune systems are different from their own. This improves the probability that the children will be resistant to a wider range of possible diseases. https://en.wikipedia.org/wiki/Body_odour_and_sexual_attraction https://en.wikipedia.org/wiki/Body_odour_and_sexual_attracti... is one of many places that you can start learning more about this topic.

anewguy9000 7y ago

you don't need to get tested the vast majority of people (even ederly) are going to have mild flu like symptoms. stay home and get better.

fspeech 7y ago

I think the term "asymptomatic" gives a wrong picture of the severity of the disease, when various authors use it to mean "testing positive before disease onset" or even outright untested due to testing criteria and availability.

dboreham 7y ago

Two things to know: 1. The current test is designed for the scenario that someone shows up to medical provider with symptoms. Test answers the question: are the symptoms caused by COVID-19?, quite reliably (negligible false positives, low false negatives). 2. The current test won't produce terribly useful data in someone without symptoms (either before, or after the illness). This is why for example certain well-known political figures saying they have been tested and cleared after potential exposure is not very meaningful. Therefore ideas like: let's randomly test the population to see how much of this is out there, and I had what I think was COVID-19, I want to be tested to confirm, are not practical. A test that can determine if someone was infected in the past is in development still.

dueh3brhdudu 7y ago
Number 2 is misleading, Trump got tested to quell opponents' fear mongering about his health. That doesn't make it more useful scientifically but no one thought it was happening for science anyway.
wool_gather 7y ago
I'm curious about the technical reasons for what you're saying. Can you say more? Is it a problem with figuring out the false negative rate for people without symptoms?
- PeterisP 7y ago
  If you test on antigen that matches the virus, then that will return a negative result in the very beginning of infection and after recovery. If you want accurate numbers for statistics, including people who never had symptoms, you can do antibody testing on a random sample of population, that will indicate people who had the disease - but that's kind of too late for that particular location and those particular patients, that's for epidemiological studies and helping other locations. I recall reading about one such study for Covid, but I don't remember which country did it.
  - djsumdog 7y ago

3fe9a03ccd14ca5 7y ago

Not to mention it is still extremely difficult to be tested in the US. Yes, doctors can test you, but you basically can’t get a test unless you have all of the symptoms and are sick enough to need to visit the ER.

PragmaticPulp 7y ago

> I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado. I'm glad you're better. Please be careful going forward, though. You shouldn't assume you have an immunity unless you have a positive test result. Even with the strict pre-test screening that focus strictly on high probability patients, some locations are reporting very high (90%) negative test results from assumed cases. It's best to continue practicing safety cautions as if you did not have a COVID-19 infection

mattnewton 7y ago
We are also not 100% certain that having the virus once grants immunity. People have tested positive again after appearing to make a full recovery. While these results are probably better explained by remaining infected and becoming asymptomatic for a period then getting symptoms again, we can’t yet rule out the possibility of reinfection to my knowledge. https://www.latimes.com/world-nation/story/2020-03-13/china-japan-korea-coronavirus-reinfection-test-positive https://www.latimes.com/world-nation/story/2020-03-13/china-...
- djsumdog 7y ago
  I've heard this before and it's the most troubling. Humans have adaptive immune systems. When our bodies first encounter a virus and a while blood cell successfully attaches too and breaks down a virus, it should either replicate or release the right activator proteins that will aid in breaking down the virus. Vaccines are all about tricking our immune system into preparing those specific antibodies before an infection occurs, so it can stop it quickly. If reinfection is true, what does that say about the nature of this virus and how difficult it is to create a vaccine? Are there other viruses that reinfect like this?
  - sojournerc 7y ago
    I've also heard it, but I think we need more data. If true, it would go against all priors for how humans build immunity to viruses - especially coronavirus (common cold). There may be a time limit to immunity, but having none at all after recovery would be rare indeed. Without significant evidence (more than one somewhat anecdotal case of re-emergence), there's little reason to assume the body doesn't "remember" the virus after recovery with antibodies. Seems like unnecessary FUD to spread that idea around without more evidence.

3JPLW 7y ago

It seems like you're pushing back on the CFR, possibly driven by trying to pessimize the need for action. In the small Italian city of Nembro in Bergamo, 0.6% of their entire population has died in the last 12 days. That's 70 people in a small town of 11,000 — typically there are fewer than 70 deaths every six months. Now we're certainly _overestimating_ the denominator and still getting a number that's larger than the flu. While the numerator is also an overestimate (because it includes deaths not related to COVID-19), their healthcare system is stretched beyond capacity due to the virus leading to difficulties treating all illnesses and traumas. https://www.washingtonpost.com/world/europe/coronavirus-obituaries-bergamo-italy/2020/03/16/6c342f02-66c7-11ea-b199-3a9799c54512_story.html https://www.washingtonpost.com/world/europe/coronavirus-obit...

guscost 7y ago
You should include demographic information, since it is relevant to your argument: [Nembro] Age Distribution (E 2019) 0-9 years 1,018 10-19 years 1,191 20-29 years 1,179 30-39 years 1,192 40-49 years 1,640 50-59 years 1,850 60-69 years 1,465 70-79 years 1,181 80+ years 810 > In 2010, there were 119,551 people residing in Bergamo (in which the greater area has about 500 000 inhabitants), located in the province of Bergamo, Lombardia, of whom 46.6% were male and 53.4% were female. Minors (children ages 18 and younger) totalled 16.79 percent of the population compared to pensioners who number 23.61 percent. This compares with the Italian average of 17.88 percent (minors) and 20.29 percent (pensioners). https://www.citypopulation.de/en/italy/lombardia/bergamo/016144__nembro/ https://www.citypopulation.de/en/italy/lombardia/bergamo/016... https://en.wikipedia.org/wiki/Bergamo#Demographics https://en.wikipedia.org/wiki/Bergamo#Demographics
- 3JPLW 7y ago
  Cool, thanks for the data. Looks like their population is 30% over 60, whereas the US (for example) is 20%. Even if we assume _every_ death is someone over 60 (it's not), that'd adjust the percentage to 0.4% in a generic US town. Note that Florida is similarly 28% over 60.
  - 7y ago

BiteCode_dev 7y ago

People are mostly looking at the death count, which is still very low for a pandemic. It's hard to convince people to sacrifice so much when they look outside their windows and see nothing special, plus read the news and find that some bomb/earth quake/accident somewhere killed more people in a day than the corona virus in a month.

CydeWeys 7y ago

There is a blood serum test already available that can determine if you had coronavirus (by testing for COVID-specific antibodies produced by your body). I'd say wait until the pandemic dies down and then go get that if you're curious. There's going to be some very interesting population studies done post-pandemic to determine exactly what percentage of people had asymptomatic cases (and thus could have unknowingly been contributing to the spread).

lihaciudaniel 7y ago

>I'm fairly certain I've just recovered from COVID-19 given my symptoms, but can't get tested here in Colorado Wow that really sucks, you must be the first HNer, also symptoms include fever and dry cough

naasking 7y ago

> Because of the dearth of testing in the US, it seems highly likely that far more people are infected, and maybe even recovered. It's not just highly likely, it's absolutely certain. I recommend the recent Khan academy video on this if you want to understand the math and you want a healthy dose of panic: https://www.youtube.com/watch?v=mCa0JXEwDEk https://www.youtube.com/watch?v=mCa0JXEwDEk

dboreham 7y ago

>I wish this was reflected more in the numbers being presented by various authorities. UK authorities presented this exact number at their press conference last week.

baron_harkonnen 7y ago

> This unknown denominator can change mortality rate, and severe case rate by orders of magnitude. The two best data points we have would be South Korea and the Diamond Princess cruise ship. Both of these groups have high rates of testing and both have had enough time that we can know how the most of the cases played out, and in both cases we see the death rate at about 1%. This doesn't take into account possibly different age group distributions. The cruise ship probably has less children and less 80+ people than on typical distributions. Additionally both the Diamond Princess and South Korea cases assume ready access to medical treatment. If the medical system is overwhelmed we will see much higher CFR due to critical cases not receiving adequate care.