6 ms·

This model is nice in principle, but its results depend crucially on what is ultimately an educated guess of the reporting rate of symptomatic cases. This para

by svara 7y ago

This model is nice in principle, but its results depend crucially on what is ultimately an educated guess of the reporting rate of symptomatic cases. This parameter can be found experimentally by testing for antibodies against the virus in a random sample of the population. This has not been done so far. As long as that's true, CFR estimates will be quite uncertain. Also really interesting in this context is how Germany is looking more and more like a huge outlier in terms of fatality. Almost 1000 cases and 0 deaths so far. Sure, that may still change, but the outbreak has been going on for a while there already.

bjourne 7y ago
But can you know that Germany is an outlier? Germany likely has a higher reporting rate than China so its numbers should be closer to the truth.
- svara 7y ago
  Exactly my point ;)
- chefkoch 7y ago
  Germany is not testing nearly enough people. There are lots of reports of people with legitimate concerns that did not find a way to get tested. Northern italy is like 2 hours by car and each weekend thousands drive there for a short trip.
  - svara 7y ago
    Something needs to explain the difference though between 939:0 in Germany and, e.g., 949:11 in France. Maybe the diagnoses in Germany are closer in time to infections? That would still point to a higher reporting rate in Germany vs. other countries.
    - usrusr 7y ago
      France has had a continuous epidemic since early on, but Germany successfully contained the first outbreak (thanks to one phone call from China at the right time), then it was all quiet for a while and only now Germany is catching up in case count, at a very high speed. This means that Frances, with a comparable total, has far more cases that are old enough to have already played out negatively.
      - svara 7y ago
        That's not true, case numbers in France and Germany are highly correlated. What you are saying would imply a substantial difference in growth rate between the two countries, which is easily disproved by looking at the data.
      - ernesth 7y ago
        Germany and France have had very parallel number of cases: see https://github.com/CSSEGISandData/COVID-19/blob/master/csse_covid_19_data/csse_covid_19_time_series/time_series_19-covid-Confirmed.csv https://github.com/CSSEGISandData/COVID-19/blob/master/csse_... The first case in Germany was 3 days after the first in France. They reached 4 cases the same day. When France hit 11 cases, Germany already had 13 and for 15 days they both only got 1 to 3 more cases in total. They both began increasing a lot on the 26th of February.
        usrusr 7y ago
        I haven't followed the French situation closely, are the late February cases in France clearly unrelated to early February cases or could they be the result of a phase of undetected spread?
        mygo 7y ago
        You’re assuming that the reporting in Germany is the same as the reporting in France. While they reached 4 cases the same day, that doesn’t mean that they had the same number of unknown infections. Let’s say France had 10x as many unknown infections than Germany. How would that impact the disparity in death count? And is this even a large enough sample size for that disparity to not just be explained to a high degree by mere chance?
  - keymone 7y ago
    > Germany is not testing nearly enough people Source? I’ve heard exactly the opposite - Germany is testing the whole cluster as soon as infection is found. That explains the low mortality.
    - xatxat 7y ago
      In Germany they are tracking down clusters. As a random person you won't get tested, unless you visited a risky region, had contact with an infected person or your doctor orders a test for you. As a German, this strategy makes sense to me.
      - efdee 7y ago
        Considering the shortage of reagentia for these tests, that definitely makes sense. Belgium only does tests on people who have recently been in regions at risk (China, Italy) or who have symptoms of pneumonia. 200 infected to date, zero deaths (so far).
      - keymone 7y ago
        Yep, that’s my understanding too and it makes perfect sense.
    - eggie 7y ago
      The low mortality is likely due to the recent introduction of the virus into the community there. It takes weeks to go from infection to ICU.
      - pelasaco 7y ago
        fair observation.
      - keymone 7y ago
        That’s incorrect, Germany is very much like France in terms of number of cases and their duration.
Maro 7y ago
I also saw this and found it odd. Assuming p=0.01, N=1000, k=0, the binomial probability is 0.00004317. At p=0.02, 0.03 it's even lower.
- cat199 7y ago
  not following closely, but unfortunately i don't think the data is good enough to take a hard-stats point of view of significance - take for example the rest home cluster in washington state which would hugely skew the results on a 1k sample size.
not_a_moth 7y ago
Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the age group breakdown. If I had to guess why CFR is so much lower in S Korea, it's because they tend to test more widely, ie. don't only test when patients show up at the hospital with severe symptoms. Or in other words they are closer to the real CFR.
- codeulike 7y ago
  Yes South Korea are testing huge numbers. Worth watching closely.
- lifthrasiir 7y ago
  > Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the age group breakdown. As of 2020-03-08 0:00 AM UTC+9 [1]: Patients Deaths Age (% of total) (% in group) 80+ 212 (3.0%) 14 (6.6%) 70--79 409 (5.7%) 18 (4.4%) 60--69 878 (12.3%) 11 (1.3%) 50--59 1349 (18.9%) 5 (0.4%) 40--49 975 (13.7%) 1 (0.1%) 30--39 760 (10.7%) 1 (0.1%) 20--29 2133 (29.9%) 0 (0.0%) 10--19 360 (5.0%) 0 (0.0%) 0--9 58 (0.8%) 0 (0.0%) Total 7134 50 (0.7%) [1] https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=158364414115900.pdf&rs=/upload_comm/docu/0015/ https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=15836441... (p. 10)
  - lern_too_spel 7y ago
    Most of Korea's cases were discovered since late February and have not had a chance to either recover or die (i.e., the numerator is right-censored). Expect the CFR to rise there.
    - lifthrasiir 7y ago
      You are right. If you want some other statistics, as of 2020-03-07 there were 59 patients [1] that are under respiratory support or oxygen therapy and thus considered "severe". [1] https://www.yna.co.kr/view/AKR20200307046000017 https://www.yna.co.kr/view/AKR20200307046000017
codeulike 7y ago
South Korea are testing huge numbers of people, 10,000 per day, so the stats from there are instructive
qiqitori 7y ago
Germany's outbreak has not been going on for a while. They had 79 cases one week ago (https://web.archive.org/web/20200301001656/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200301001656/https://www.world...), and the number was 16 two weeks ago (https://web.archive.org/web/20200223003733/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200223003733/https://www.world...), and 14 four weeks ago (https://web.archive.org/web/20200210100748/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200210100748/https://www.world...). It takes weeks to die after getting infected.
- usrusr 7y ago
  That, and with Christmas still in living memory the endangered age bracket is effectively quarantined anyways, not expecting the the next quarterly visit from children and grandchildren before the end of the month. Germany is a country of lonely old people.
- SpicyLemonZest 7y ago
  79 cases last week to 1000 today doesn't indicate that there's been a new outbreak this week; it indicates that there's been an outbreak for a while and they're just now noticing. Those 79 people alone couldn't have infected 1000.
- svara 7y ago
  That's not all there is to it, since the number of people infected grew at a similar pace in the early phase of an outbreak in different countries. For example, the number of people infected in France and Germany is rising in near perfect synchrony, but France has 11 deaths now. Similarly, growth in the early phase of the South Korea outbreak looks nearly identical to Germany and France (with a ca. 2 week delay), and they had 10 deaths when they had 1000 infected. Germany is looking increasingly anomalous every day. There has to be a difference with respect to detection, unless it's something more out there like viral strain differences.
  - grammerguy 7y ago
    Actually, to the point of viral strain differences, I did come across this paper indicating exactly that idea— that there are two strains. I am not a scientist, so I cannot evaluate the veracity of the claims, but did find the work interesting and compelling: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463 https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr...

by svara 7y ago

bjourne 7y ago

But can you know that Germany is an outlier? Germany likely has a higher reporting rate than China so its numbers should be closer to the truth.

svara 7y ago
Exactly my point ;)
chefkoch 7y ago
Germany is not testing nearly enough people. There are lots of reports of people with legitimate concerns that did not find a way to get tested. Northern italy is like 2 hours by car and each weekend thousands drive there for a short trip.
- svara 7y ago
  Something needs to explain the difference though between 939:0 in Germany and, e.g., 949:11 in France. Maybe the diagnoses in Germany are closer in time to infections? That would still point to a higher reporting rate in Germany vs. other countries.
  - usrusr 7y ago
    France has had a continuous epidemic since early on, but Germany successfully contained the first outbreak (thanks to one phone call from China at the right time), then it was all quiet for a while and only now Germany is catching up in case count, at a very high speed. This means that Frances, with a comparable total, has far more cases that are old enough to have already played out negatively.
    - svara 7y ago
      That's not true, case numbers in France and Germany are highly correlated. What you are saying would imply a substantial difference in growth rate between the two countries, which is easily disproved by looking at the data.
    - ernesth 7y ago
      Germany and France have had very parallel number of cases: see https://github.com/CSSEGISandData/COVID-19/blob/master/csse_covid_19_data/csse_covid_19_time_series/time_series_19-covid-Confirmed.csv https://github.com/CSSEGISandData/COVID-19/blob/master/csse_... The first case in Germany was 3 days after the first in France. They reached 4 cases the same day. When France hit 11 cases, Germany already had 13 and for 15 days they both only got 1 to 3 more cases in total. They both began increasing a lot on the 26th of February.
      - usrusr 7y ago
        I haven't followed the French situation closely, are the late February cases in France clearly unrelated to early February cases or could they be the result of a phase of undetected spread?
      - mygo 7y ago
        You’re assuming that the reporting in Germany is the same as the reporting in France. While they reached 4 cases the same day, that doesn’t mean that they had the same number of unknown infections. Let’s say France had 10x as many unknown infections than Germany. How would that impact the disparity in death count? And is this even a large enough sample size for that disparity to not just be explained to a high degree by mere chance?
- keymone 7y ago
  > Germany is not testing nearly enough people Source? I’ve heard exactly the opposite - Germany is testing the whole cluster as soon as infection is found. That explains the low mortality.
  - xatxat 7y ago
    In Germany they are tracking down clusters. As a random person you won't get tested, unless you visited a risky region, had contact with an infected person or your doctor orders a test for you. As a German, this strategy makes sense to me.
    - efdee 7y ago
      Considering the shortage of reagentia for these tests, that definitely makes sense. Belgium only does tests on people who have recently been in regions at risk (China, Italy) or who have symptoms of pneumonia. 200 infected to date, zero deaths (so far).
    - keymone 7y ago
      Yep, that’s my understanding too and it makes perfect sense.
  - eggie 7y ago
    The low mortality is likely due to the recent introduction of the virus into the community there. It takes weeks to go from infection to ICU.
    - pelasaco 7y ago
      fair observation.
    - keymone 7y ago
      That’s incorrect, Germany is very much like France in terms of number of cases and their duration.

Maro 7y ago

I also saw this and found it odd. Assuming p=0.01, N=1000, k=0, the binomial probability is 0.00004317. At p=0.02, 0.03 it's even lower.

cat199 7y ago
not following closely, but unfortunately i don't think the data is good enough to take a hard-stats point of view of significance - take for example the rest home cluster in washington state which would hugely skew the results on a 1k sample size.

not_a_moth 7y ago

Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the age group breakdown. If I had to guess why CFR is so much lower in S Korea, it's because they tend to test more widely, ie. don't only test when patients show up at the hospital with severe symptoms. Or in other words they are closer to the real CFR.

codeulike 7y ago
Yes South Korea are testing huge numbers. Worth watching closely.
lifthrasiir 7y ago
> Or look at S Korea, 7313 cases 50 deaths, .68% CFR. Would like to see the age group breakdown. As of 2020-03-08 0:00 AM UTC+9 [1]: Patients Deaths Age (% of total) (% in group) 80+ 212 (3.0%) 14 (6.6%) 70--79 409 (5.7%) 18 (4.4%) 60--69 878 (12.3%) 11 (1.3%) 50--59 1349 (18.9%) 5 (0.4%) 40--49 975 (13.7%) 1 (0.1%) 30--39 760 (10.7%) 1 (0.1%) 20--29 2133 (29.9%) 0 (0.0%) 10--19 360 (5.0%) 0 (0.0%) 0--9 58 (0.8%) 0 (0.0%) Total 7134 50 (0.7%) [1] https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=158364414115900.pdf&rs=/upload_comm/docu/0015/ https://is.cdc.go.kr/upload_comm/syview/doc.html?fn=15836441... (p. 10)
- lern_too_spel 7y ago
  Most of Korea's cases were discovered since late February and have not had a chance to either recover or die (i.e., the numerator is right-censored). Expect the CFR to rise there.
  - lifthrasiir 7y ago
    You are right. If you want some other statistics, as of 2020-03-07 there were 59 patients [1] that are under respiratory support or oxygen therapy and thus considered "severe". [1] https://www.yna.co.kr/view/AKR20200307046000017 https://www.yna.co.kr/view/AKR20200307046000017

codeulike 7y ago

South Korea are testing huge numbers of people, 10,000 per day, so the stats from there are instructive

qiqitori 7y ago

Germany's outbreak has not been going on for a while. They had 79 cases one week ago (https://web.archive.org/web/20200301001656/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200301001656/https://www.world...), and the number was 16 two weeks ago (https://web.archive.org/web/20200223003733/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200223003733/https://www.world...), and 14 four weeks ago (https://web.archive.org/web/20200210100748/https://www.worldometers.info/coronavirus/ https://web.archive.org/web/20200210100748/https://www.world...). It takes weeks to die after getting infected.

usrusr 7y ago
That, and with Christmas still in living memory the endangered age bracket is effectively quarantined anyways, not expecting the the next quarterly visit from children and grandchildren before the end of the month. Germany is a country of lonely old people.
SpicyLemonZest 7y ago
79 cases last week to 1000 today doesn't indicate that there's been a new outbreak this week; it indicates that there's been an outbreak for a while and they're just now noticing. Those 79 people alone couldn't have infected 1000.
svara 7y ago
That's not all there is to it, since the number of people infected grew at a similar pace in the early phase of an outbreak in different countries. For example, the number of people infected in France and Germany is rising in near perfect synchrony, but France has 11 deaths now. Similarly, growth in the early phase of the South Korea outbreak looks nearly identical to Germany and France (with a ca. 2 week delay), and they had 10 deaths when they had 1000 infected. Germany is looking increasingly anomalous every day. There has to be a difference with respect to detection, unless it's something more out there like viral strain differences.
- grammerguy 7y ago
  Actually, to the point of viral strain differences, I did come across this paper indicating exactly that idea— that there are two strains. I am not a scientist, so I cannot evaluate the veracity of the claims, but did find the work interesting and compelling: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaa036/5775463 https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr...