7 ms·

We already have lots of data that says this is not true. For instance, on the Diamond Princess, widespread testing of a confined group initially found many asy

We already have lots of data that says this is not true. For instance, on the Diamond Princess, widespread testing of a confined group initially found many asymptomatic infections, but the majority of those turned out to be pre-symptomatic, not asymptomatic. Longer term follow-up found ~25% of infections were asymptomatic. In the US, we're now doing significant amounts of testing, but we're still primarily testing only those with severe symptoms. Even limiting our sample to people presenting with severe matching symptoms of COVID-19, we're finding ~20% PCR-positive for SARS-CoV-2. Beyond that, we also have good evidence that the Basic Reproduction Number is somewhere between 2-3. Given a seeding of cases in mid-to-late January, even without social distancing measures, it would be unlikely to have 10% of the population infected yet.

onlyrealcuzzo 7y ago
For reference, ~19% of people get the flu and are asymptomatic. Source: https://www.contagionlive.com/news/asymptomatic-influenza-infection-rates-deserve-more-attention https://www.contagionlive.com/news/asymptomatic-influenza-in... > Study results revealed an overall pooled prevalence for asymptomatic carriers of 19.1% for any type of influenza, 21.0% for influenza A, and 22.7% for influenza A(H1N1). For subclinical carriers, the overall pooled prevalence of was found to be 43.4% for any type of influenza, 42.8% for influenza A, and 39.8% for influenza A(H1N1).
sauwan 7y ago
The Diamond Princess likely had a very atypical (older) population than the general population though. The CDC is currently estimating an R0 of 5.7, which has likely been repressed by shelter in place orders. But even if it was only 4 before any interventions, there's still a chance there there are closer to 20M cases in the US rather than the 660,000 now. My point is just that there's still a lot we don't know, and small changes in our understanding could implicate massive changes in the reality on the ground.
- ksaun 7y ago
  Here is a reference for the R0 = 5.7 estimate: https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article
- usaar333 7y ago
  5.7 in Wuhan. That could be true for NYC as well, but is far less likely to be true in the rest of the lower density country. That said I agree with you that infections are likely in the 10M range.
- wutbrodo 7y ago
  > The Diamond Princess likely had a very atypical (older) population than the general population though. This would dovetail with the fact that places like sub-Saharan Africa and India haven't been hit very hard yet; they also happen to be _very_ young compared to Western countries.
  - dguaraglia 7y ago
    I don't know if people are aware of this, but there's an increasing suspicion that countries still using the BCG vaccine for tuberculosis might be seeing [1]way lower infection rates. If that's the case, it'd explain why developed countries are bearing the brunt of the pandemic. A very interesting example of similarly developed countries with comparable (but not equal) populations and population density, but different vaccination regimes are Portugal and Spain. Looking at their [2]respective [3]charts, the differences are stark. A similar difference can be seen between Ecuador and Argentina, even though the Greater Buenos Aires area is very population dense. If this pans out, following the trends and [4] this map would validate that hypothesis. [1]https://nypost.com/2020/04/14/coronavirus-death-rates-lower-in-countries-using-tb-vaccine/ https://nypost.com/2020/04/14/coronavirus-death-rates-lower-... [2]https://www.worldometers.info/coronavirus/country/portugal/ https://www.worldometers.info/coronavirus/country/portugal/ [3]https://www.worldometers.info/coronavirus/country/spain/ https://www.worldometers.info/coronavirus/country/spain/ [4]http://www.bcgatlas.org/ http://www.bcgatlas.org/
    - perl4ever 7y ago
      "there's an increasing suspicion that countries still using the BCG vaccine for tuberculosis might be seeing [1]way lower infection rates" Obvious to me, perhaps dumb, question - if countries that were slower to change vaccination regimes have some advantage, then wouldn't we see older people in the countries that did change also at an advantage? Yet all reporting seems to be that older people are harder hit.
      - coliveira 7y ago
        BCG vaccine requires a booster every few decades, so it becomes less effective over the years. Apart from health issues related to age, this would explain why old people are at higher risk.
gridlockd 7y ago
If you already have severe symptoms the PCR test from a throat sample is likely to give a false negative. The BPR is estimated from the known cases, so it cannot tell you anything about a hypothetical large number of unknown cases. Antibody tests in a recent German study of households gave 15% infection rate.
- jsnell 7y ago
  It wasn't a study of representative German households, but just those in a Gangelt. A small town that was basically the ground zero for the epidemic in Germany. Those numbers do not generalize to Germany as a whole, let alone other countries. Also, the particular antibody tests they used appears to have a much higher FP rate than they claimed. Another study found 4% FPs rather than <1% like the press release for the Gangelt testing claimed.
  - gridlockd 7y ago
    It does generalize to my point, because we're talking about the basic reproduction number of the virus. It is not supposed to vary dramatically across populations. If COVID-19 can spread to 15% of that particular population within that timeframe, and the estimate of a basic reproduction number of 2-3 predicts that this is not possible, then the estimate must be wrong. > Also, the particular antibody tests they used appears to have a much higher FP rate than they claimed. Another study found 4% FPs rather than <1% like the press release for the Gangelt testing claimed. Perhaps, but that doesn't put much of a dent into the results.
    - jsnell 7y ago
      R0 isn't a fundamental constant, but just an estimated average. It's affected both by human behavior and random chance. In this case, the town had a very early superspreader event, which shifted them far ahead of the curve. A FP rate that high will make a very significant difference in the results. (How large a difference depends on whether the 15% is a raw number or if it's been adjusted based on the expected test specificity and sensitivity. One would hope nobody would just report the raw numbers. But since all we've gotten from this study is basically a press release, expecting scientific rigor seems ill advised.)
cgb223 7y ago
> In the US, we're now doing significant amounts of testing, but we're still primarily testing only those with severe symptoms Its not a significant amount of testing if we're only testing those with severe symptoms Here in SF at least there are scores of people I know who all were sick with a "weird flu" at some point from February to now who would all kill for a test to show that they have COVID immunity. These are people who could potentially go back into society and do more work / enjoy their lives instead of being shuttered inside with anxiety It is currently _IMPOSSIBLE_ to get any kind of test to prove that
- abarringer 7y ago
  Only way I know to get any COVID19 antibody test is through this study https://clinicaltrials.gov/ct2/show/NCT04334954?term=serosurvey&cond=covid-19&draw=2&rank=1 https://clinicaltrials.gov/ct2/show/NCT04334954?term=serosur... and the result may be inconclusive or take months.
  - blhack 7y ago
    This is weird to hear because there are several competing clinics in Phoenix all offering antibody testing.
- beamatronic 7y ago
  Go do the Stanford drive-through blood antibody tests. It takes five minutes it’s free and they do it for everybody.
  - cgb223 7y ago
    Do you need any kind of doctors order for that or health insurance? Like how does it work? Would love to go do that
  - DrScump 7y ago
    it’s free and they do it for everybody Do you have details on how to take advantage of this? Their website says nothing to to that effect: https://med.stanford.edu/covid19.html https://med.stanford.edu/covid19.html
MiguelVieira 7y ago
Likewise, South Korea reports a fatality rate of about 2% https://www.worldometers.info/coronavirus/country/south-korea/ https://www.worldometers.info/coronavirus/country/south-kore... Since they have coronavirus relatively under control and have been doing extensive testing and contact tracing for months, it's plausible that they've caught most cases. It's wishful thinking to believe the infection fatality rate is an order of magnitude lower.
- usaar333 7y ago
  It is not plausible they caught most cases. Here's the result of randomized testing in Iceland, which also has the virus under control and has done even more testing per capita (https://www.nejm.org/doi/full/10.1056/NEJMoa2006100?query=featured_coronavirus https://www.nejm.org/doi/full/10.1056/NEJMoa2006100?query=fe...) Randomized testing was still finding 0.6% of the population (outside those otherwise quarantined already) actively infected. This means even in Iceland, less than half of infections were being caught. Iceland's CFR right now is 0.74% using deaths/recovered (or if you use an ultimate 20% hospitalization fatality rate, around 0.87%). If they missed half of infections, you get an IFR down to under 0.5%, though I'll admit they are doing better by keeping their most vulnerable population from being infected. (note the low infection rate for people 70+ at https://www.covid.is/data https://www.covid.is/data). So no, not an order of magnitude lower, but 3x lower (0.7%) is looking pretty reasonable. Imperial College's latest estimate is 0.66% for China (https://www.medrxiv.org/content/10.1101/2020.03.09.20033357v1 https://www.medrxiv.org/content/10.1101/2020.03.09.20033357v...).
  - rocha 7y ago
    The comparison between the two countries is so difficult. The population of Iceland is around 360K, while South Korea is over 51 million (~140x). The population density is in the same order, 3 per Km^2 to 500 per Km^2 respectively (~160x).
  - halfdan 7y ago
    Half of Iceland's population lives in the Reykjavik area. The rest are thinly spread out over the country - which of which is still inaccessible due to ice (usually until April/May). Comparing this to a densely populated South Korea is incredibly difficult.
throwaway_USD 7y ago
>We already have lots of data that says this is not true... Longer term follow-up found ~25% of infections were asymptomatic. Based on other available data the severity of the Covid symptoms are dependent on both the length of exposure and total exposure to the virus. A cruise ship with recirculated air likely means prolonged exposure to high concentrations of the virus that won't fit most other patients exposure.
throwaway_pdp09 7y ago
> good evidence that the Basic Reproduction Number is somewhere between 2-3. May be about double that. Per wiki article, I noticed this a few days ago (https://en.wikipedia.org/wiki/2019%E2%80%9320_outbreak_of_novel_coronavirus_%282019-nCoV%29 https://en.wikipedia.org/wiki/2019%E2%80%9320_outbreak_of_no...) "Initial estimates of the basic reproduction number (R0) for COVID-19 in January were between 1.4 and 2.5,[381] but a subsequent statistical analysis has concluded that it may be much higher.[382]" From that link wiki provided (https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article) (edit: and note this is published on the CDC website) "...we calculated a median R0 value of 5.7 (95% CI 3.8–8.9)" So this sucks harder then.
smsm42 7y ago
What's "significant amount of testing"? In Santa Clara country, for example, 16585 tests have been done[1], that's less than 1% of the population. I know from personal experience of several people that it's next to impossible to get tested if you don't have very severe symptoms. Positivity rate is 10.8% - over people which are sick enough to get tested. > Given a seeding of cases in mid-to-late January, even without social distancing measures, it would be unlikely to have 10% of the population infected yet This sounds like circular logic - how we know it indeed started in January and not before? How do we know how many had it asymptomatically if we didn't test 99% of the population? We're making assumption based on knowledge gathered by select sample of 1% chosen by severity of symptoms - how can we make conclusion about how it works in the rest of the population and what's the dynamics there? [1] https://www.sccgov.org/sites/covid19/Pages/dashboard.aspx https://www.sccgov.org/sites/covid19/Pages/dashboard.aspx
- jlmorton 7y ago
  > This sounds like circular logic - how we know it indeed started in January and not before? Indeed, without serological testing, we're necessarily making some assumptions. But there's other evidence that points this way, too. Genetic analysis based on samples from around China and the world point to a single index patient in Hubei Province around late November. China's case tracing has not gotten to an index patient, but it appears to be pretty close, and also points to an initial case around the same time. If there was a single case in late November, then we'd expect a few hundred cases by January. Some number of these will have traveled, but many would not. While the US clearly had major blind spots in testing, we were explicitly looking for symptomatic cases from China. The first detected case was Jan 21. There may have been a few earlier, but genetic analysis of cases in Washington point to an index patient in the Seattle area around that time.

onlyrealcuzzo 7y ago

For reference, ~19% of people get the flu and are asymptomatic. Source: https://www.contagionlive.com/news/asymptomatic-influenza-infection-rates-deserve-more-attention https://www.contagionlive.com/news/asymptomatic-influenza-in... > Study results revealed an overall pooled prevalence for asymptomatic carriers of 19.1% for any type of influenza, 21.0% for influenza A, and 22.7% for influenza A(H1N1). For subclinical carriers, the overall pooled prevalence of was found to be 43.4% for any type of influenza, 42.8% for influenza A, and 39.8% for influenza A(H1N1).

sauwan 7y ago

The Diamond Princess likely had a very atypical (older) population than the general population though. The CDC is currently estimating an R0 of 5.7, which has likely been repressed by shelter in place orders. But even if it was only 4 before any interventions, there's still a chance there there are closer to 20M cases in the US rather than the 660,000 now. My point is just that there's still a lot we don't know, and small changes in our understanding could implicate massive changes in the reality on the ground.

ksaun 7y ago
Here is a reference for the R0 = 5.7 estimate: https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article
usaar333 7y ago
5.7 in Wuhan. That could be true for NYC as well, but is far less likely to be true in the rest of the lower density country. That said I agree with you that infections are likely in the 10M range.
wutbrodo 7y ago
> The Diamond Princess likely had a very atypical (older) population than the general population though. This would dovetail with the fact that places like sub-Saharan Africa and India haven't been hit very hard yet; they also happen to be _very_ young compared to Western countries.
- dguaraglia 7y ago
  I don't know if people are aware of this, but there's an increasing suspicion that countries still using the BCG vaccine for tuberculosis might be seeing [1]way lower infection rates. If that's the case, it'd explain why developed countries are bearing the brunt of the pandemic. A very interesting example of similarly developed countries with comparable (but not equal) populations and population density, but different vaccination regimes are Portugal and Spain. Looking at their [2]respective [3]charts, the differences are stark. A similar difference can be seen between Ecuador and Argentina, even though the Greater Buenos Aires area is very population dense. If this pans out, following the trends and [4] this map would validate that hypothesis. [1]https://nypost.com/2020/04/14/coronavirus-death-rates-lower-in-countries-using-tb-vaccine/ https://nypost.com/2020/04/14/coronavirus-death-rates-lower-... [2]https://www.worldometers.info/coronavirus/country/portugal/ https://www.worldometers.info/coronavirus/country/portugal/ [3]https://www.worldometers.info/coronavirus/country/spain/ https://www.worldometers.info/coronavirus/country/spain/ [4]http://www.bcgatlas.org/ http://www.bcgatlas.org/
  - perl4ever 7y ago
    "there's an increasing suspicion that countries still using the BCG vaccine for tuberculosis might be seeing [1]way lower infection rates" Obvious to me, perhaps dumb, question - if countries that were slower to change vaccination regimes have some advantage, then wouldn't we see older people in the countries that did change also at an advantage? Yet all reporting seems to be that older people are harder hit.
    - coliveira 7y ago
      BCG vaccine requires a booster every few decades, so it becomes less effective over the years. Apart from health issues related to age, this would explain why old people are at higher risk.

gridlockd 7y ago

If you already have severe symptoms the PCR test from a throat sample is likely to give a false negative. The BPR is estimated from the known cases, so it cannot tell you anything about a hypothetical large number of unknown cases. Antibody tests in a recent German study of households gave 15% infection rate.

jsnell 7y ago
It wasn't a study of representative German households, but just those in a Gangelt. A small town that was basically the ground zero for the epidemic in Germany. Those numbers do not generalize to Germany as a whole, let alone other countries. Also, the particular antibody tests they used appears to have a much higher FP rate than they claimed. Another study found 4% FPs rather than <1% like the press release for the Gangelt testing claimed.
- gridlockd 7y ago
  It does generalize to my point, because we're talking about the basic reproduction number of the virus. It is not supposed to vary dramatically across populations. If COVID-19 can spread to 15% of that particular population within that timeframe, and the estimate of a basic reproduction number of 2-3 predicts that this is not possible, then the estimate must be wrong. > Also, the particular antibody tests they used appears to have a much higher FP rate than they claimed. Another study found 4% FPs rather than <1% like the press release for the Gangelt testing claimed. Perhaps, but that doesn't put much of a dent into the results.
  - jsnell 7y ago
    R0 isn't a fundamental constant, but just an estimated average. It's affected both by human behavior and random chance. In this case, the town had a very early superspreader event, which shifted them far ahead of the curve. A FP rate that high will make a very significant difference in the results. (How large a difference depends on whether the 15% is a raw number or if it's been adjusted based on the expected test specificity and sensitivity. One would hope nobody would just report the raw numbers. But since all we've gotten from this study is basically a press release, expecting scientific rigor seems ill advised.)

cgb223 7y ago

> In the US, we're now doing significant amounts of testing, but we're still primarily testing only those with severe symptoms Its not a significant amount of testing if we're only testing those with severe symptoms Here in SF at least there are scores of people I know who all were sick with a "weird flu" at some point from February to now who would all kill for a test to show that they have COVID immunity. These are people who could potentially go back into society and do more work / enjoy their lives instead of being shuttered inside with anxiety It is currently _IMPOSSIBLE_ to get any kind of test to prove that

abarringer 7y ago
Only way I know to get any COVID19 antibody test is through this study https://clinicaltrials.gov/ct2/show/NCT04334954?term=serosurvey&cond=covid-19&draw=2&rank=1 https://clinicaltrials.gov/ct2/show/NCT04334954?term=serosur... and the result may be inconclusive or take months.
- blhack 7y ago
  This is weird to hear because there are several competing clinics in Phoenix all offering antibody testing.
beamatronic 7y ago
Go do the Stanford drive-through blood antibody tests. It takes five minutes it’s free and they do it for everybody.
- cgb223 7y ago
  Do you need any kind of doctors order for that or health insurance? Like how does it work? Would love to go do that
- DrScump 7y ago
  it’s free and they do it for everybody Do you have details on how to take advantage of this? Their website says nothing to to that effect: https://med.stanford.edu/covid19.html https://med.stanford.edu/covid19.html

MiguelVieira 7y ago

Likewise, South Korea reports a fatality rate of about 2% https://www.worldometers.info/coronavirus/country/south-korea/ https://www.worldometers.info/coronavirus/country/south-kore... Since they have coronavirus relatively under control and have been doing extensive testing and contact tracing for months, it's plausible that they've caught most cases. It's wishful thinking to believe the infection fatality rate is an order of magnitude lower.

usaar333 7y ago
It is not plausible they caught most cases. Here's the result of randomized testing in Iceland, which also has the virus under control and has done even more testing per capita (https://www.nejm.org/doi/full/10.1056/NEJMoa2006100?query=featured_coronavirus https://www.nejm.org/doi/full/10.1056/NEJMoa2006100?query=fe...) Randomized testing was still finding 0.6% of the population (outside those otherwise quarantined already) actively infected. This means even in Iceland, less than half of infections were being caught. Iceland's CFR right now is 0.74% using deaths/recovered (or if you use an ultimate 20% hospitalization fatality rate, around 0.87%). If they missed half of infections, you get an IFR down to under 0.5%, though I'll admit they are doing better by keeping their most vulnerable population from being infected. (note the low infection rate for people 70+ at https://www.covid.is/data https://www.covid.is/data). So no, not an order of magnitude lower, but 3x lower (0.7%) is looking pretty reasonable. Imperial College's latest estimate is 0.66% for China (https://www.medrxiv.org/content/10.1101/2020.03.09.20033357v1 https://www.medrxiv.org/content/10.1101/2020.03.09.20033357v...).
- rocha 7y ago
  The comparison between the two countries is so difficult. The population of Iceland is around 360K, while South Korea is over 51 million (~140x). The population density is in the same order, 3 per Km^2 to 500 per Km^2 respectively (~160x).
- halfdan 7y ago
  Half of Iceland's population lives in the Reykjavik area. The rest are thinly spread out over the country - which of which is still inaccessible due to ice (usually until April/May). Comparing this to a densely populated South Korea is incredibly difficult.

throwaway_USD 7y ago

>We already have lots of data that says this is not true... Longer term follow-up found ~25% of infections were asymptomatic. Based on other available data the severity of the Covid symptoms are dependent on both the length of exposure and total exposure to the virus. A cruise ship with recirculated air likely means prolonged exposure to high concentrations of the virus that won't fit most other patients exposure.

throwaway_pdp09 7y ago

> good evidence that the Basic Reproduction Number is somewhere between 2-3. May be about double that. Per wiki article, I noticed this a few days ago (https://en.wikipedia.org/wiki/2019%E2%80%9320_outbreak_of_novel_coronavirus_%282019-nCoV%29 https://en.wikipedia.org/wiki/2019%E2%80%9320_outbreak_of_no...) "Initial estimates of the basic reproduction number (R0) for COVID-19 in January were between 1.4 and 2.5,[381] but a subsequent statistical analysis has concluded that it may be much higher.[382]" From that link wiki provided (https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article https://wwwnc.cdc.gov/eid/article/26/7/20-0282_article) (edit: and note this is published on the CDC website) "...we calculated a median R0 value of 5.7 (95% CI 3.8–8.9)" So this sucks harder then.

smsm42 7y ago

What's "significant amount of testing"? In Santa Clara country, for example, 16585 tests have been done[1], that's less than 1% of the population. I know from personal experience of several people that it's next to impossible to get tested if you don't have very severe symptoms. Positivity rate is 10.8% - over people which are sick enough to get tested. > Given a seeding of cases in mid-to-late January, even without social distancing measures, it would be unlikely to have 10% of the population infected yet This sounds like circular logic - how we know it indeed started in January and not before? How do we know how many had it asymptomatically if we didn't test 99% of the population? We're making assumption based on knowledge gathered by select sample of 1% chosen by severity of symptoms - how can we make conclusion about how it works in the rest of the population and what's the dynamics there? [1] https://www.sccgov.org/sites/covid19/Pages/dashboard.aspx https://www.sccgov.org/sites/covid19/Pages/dashboard.aspx

jlmorton 7y ago
> This sounds like circular logic - how we know it indeed started in January and not before? Indeed, without serological testing, we're necessarily making some assumptions. But there's other evidence that points this way, too. Genetic analysis based on samples from around China and the world point to a single index patient in Hubei Province around late November. China's case tracing has not gotten to an index patient, but it appears to be pretty close, and also points to an initial case around the same time. If there was a single case in late November, then we'd expect a few hundred cases by January. Some number of these will have traveled, but many would not. While the US clearly had major blind spots in testing, we were explicitly looking for symptomatic cases from China. The first detected case was Jan 21. There may have been a few earlier, but genetic analysis of cases in Washington point to an index patient in the Seattle area around that time.