5 ms·

This paper seems to have every imaginable scenario of which 2022 is a worst case. But, now actual data is starting to come in - such as the extremely interesti

This paper seems to have every imaginable scenario of which 2022 is a worst case. But, now actual data is starting to come in - such as the extremely interesting serum testing in Scotland (1) - which suggests that the infection rate is much much higher than previously supposed. The Scotland serum testing shows that around 35000 people were infected at a time when only 110 cases were known officially, and strongly suggests that at least 10%-20% of the country have been infected by now. Similar data has been suggested by the Danish serum testing. So I'd be interested to see what comes out of this Harvard model if they put in the numbers suggested from serum testing. 1. https://figshare.com/articles/Serological_analysis_of_1000_Scottish_blood_donor_samples_for_anti-SARSCoV2_antibodies_collected_in_March_2020/12116778/2 https://figshare.com/articles/Serological_analysis_of_1000_S... )

elliekelly 6y ago
When “sero samples” are done like this is there any effort to notify the donors their blood has been tested and come back positive for the antibodies? Ideally donors would be notified either way but at the very least I think the people with positive results ought to be informed.
- deleted 6y ago
  [deleted]
raphlinus 6y ago
That's a lot of interpretation from 6 cases. There's a lot of serological testing being done right now, and we'll have hard data soon, but from what I see from expert epidemiologists (disclosure: I'm not one myself), the idea that we have a vast number of completely asymptomatic cases is wishful thinking.
- JetSetWilly 6y ago
  Ah, but if you do a sample of 1000 then even low numbers of positives are still statistically significant. The poisson distribution on just 6 might be somewhat wide but you can give a reasonable confidence interval (ie 0.3-0.9%) - and either end of that interval still suggests a lot of undetected cases at a time when there was hardly any officially. What you can't do - statistically - is say "oh there were just 6, that means it all could just be a coincidence and the prevlence is actually very low". Especially when - if you dig into the numbers they make sense. First, they were spread over a 2 week period, with all the positives being in the second cohort - which is what is expected if there's an exponential explosion of cases going on. Secondly, 4 of the 6 positives are in the Edinburgh area which is the most internationally connected and affluent area of Scotland. So I really don't think it can be breezily dismissed just because you don't like the data. But as you say, we'll have a lot more serological data before long so lets see.
  - f38zf5vdt 6y ago
    edit: removed for potentially being misleading.
    - JetSetWilly 6y ago
      Cross-reactivity is an issue in the ELISA test (the actual antibody test). But they validated their results with a second step, the "pseudotype neutralisation assay". This test is highly specific for SARS-CoV-2 - as I understand it, they essentially introduce the virus to the hypothetically immune blood samples and then test that it is indeed neutralised by antibodies. So, I think this Scottish serology test is pretty robust and accounts for these issues with cross-reactivity and specificity of the testing. In addition - they used a control sample from December 2019 none of which tested positive.
      - f38zf5vdt 6y ago
        Yeah, I read more into their assay and I'm inclined to agree with you.
      - tgb 6y ago
        0 out of 100 controls and 6 out of 500 gives a very wide confidence interval. You could easily get those numbers with 1% false positives and no true positives in either group. Is your prior for false positives low enough to rule that out?
        JetSetWilly 6y ago
        They did two independent assays so I would think the false positives rate should be far below 1% - certainly the authors seem to think so. Secondly if they were false positives, I would expect them to be randomly distributed. Not concentrated in the affluent capital city, and not solely in the second cohort with none in the early march cohort (as you would predict if exponential growth is occurring).
        6y ago
- raphlinus 6y ago
  Here's an expert thread (for example): https://twitter.com/richardneher/status/1250533354560159745 https://twitter.com/richardneher/status/1250533354560159745
chvid 6y ago
There is a study in Germany done on an outbreak in Heinsberg that has a similar result.
cm2187 6y ago
And also a similar study in Germany with similar results [1]. The result is of course to mechanically reduce the fatality rate to a number close to that of the flu (the problem for hospitals being not so much the fatality rate than the high number of infections), and well within the 0.1-1% range that US health authorities have been advertising for a while. Regarding models, it seems 0.15% is the new basis [2]. Even on the optimistic end of the range (0.1% fatality), with 13k deaths, that's 20% of the UK population infected, a long way from achieving herd immunity. The other thing is that I invite people on hackernews to better control their anxiety. It is not so long ago that pointing that case fatality ratios in jurisdictions that didn't do mass testing and where there seemed to be many unreported cases with mild symptom was overestimating the fatality rate would get you treated of conspirary theorist. South Korea had been measuring a fatality ratio in that range (~0.6%) over a month ago and that was probably already an upper bound (due to not testing 100% of the population). [1] https://mobile.twitter.com/AmeshAA/status/1249446561010106370 https://mobile.twitter.com/AmeshAA/status/124944656101010637... [2] https://mobile.twitter.com/AmeshAA/status/1249020677551796224 https://mobile.twitter.com/AmeshAA/status/124902067755179622...
- guscost 6y ago
  The people who were treating that hypothesis as an absurd conspiracy theory last month probably won’t own up to it, but I do hope they are reading.
  - DanBC 6y ago
    That's not really what those people were saying. It doesn't matter if the number is 5% with a low infection rate, or 0.5% with a very high infection rate: both will lead to very large numbers of dead people unless we take severe action early on. And so far they've been right. Covid-19 is causing huge amounts of excess mortality, even when compared to a really bad flu year.
    - guscost 6y ago
      Source? Europe shows excess mortality spiking to a similar level as the 2017-2018 flu season: https://www.euromomo.eu/ https://www.euromomo.eu/ And that’s with elective procedures being cancelled and everyone scared to go to the hospital for any reason. Here’s some new data indicating that half of the excess mortality in England might not be caused by COVID-19 itself: https://archive.is/2eKCW https://archive.is/2eKCW
loftyal 6y ago
The tests might be inaccurate. Current antibody tests seem to conflate the common cold with covid-19, as they are both coronaviruses. https://edition.cnn.com/2020/04/14/health/coronavirus-antibody-tests-scientists/index.html https://edition.cnn.com/2020/04/14/health/coronavirus-antibo...
- JetSetWilly 6y ago
  That is not the case for this study, see here for why: https://news.ycombinator.com/item?id=22879363 https://news.ycombinator.com/item?id=22879363
  - loftyal 6y ago
    That is good news if that's the case!

elliekelly 6y ago

When “sero samples” are done like this is there any effort to notify the donors their blood has been tested and come back positive for the antibodies? Ideally donors would be notified either way but at the very least I think the people with positive results ought to be informed.

deleted 6y ago
[deleted]

raphlinus 6y ago

That's a lot of interpretation from 6 cases. There's a lot of serological testing being done right now, and we'll have hard data soon, but from what I see from expert epidemiologists (disclosure: I'm not one myself), the idea that we have a vast number of completely asymptomatic cases is wishful thinking.

JetSetWilly 6y ago
Ah, but if you do a sample of 1000 then even low numbers of positives are still statistically significant. The poisson distribution on just 6 might be somewhat wide but you can give a reasonable confidence interval (ie 0.3-0.9%) - and either end of that interval still suggests a lot of undetected cases at a time when there was hardly any officially. What you can't do - statistically - is say "oh there were just 6, that means it all could just be a coincidence and the prevlence is actually very low". Especially when - if you dig into the numbers they make sense. First, they were spread over a 2 week period, with all the positives being in the second cohort - which is what is expected if there's an exponential explosion of cases going on. Secondly, 4 of the 6 positives are in the Edinburgh area which is the most internationally connected and affluent area of Scotland. So I really don't think it can be breezily dismissed just because you don't like the data. But as you say, we'll have a lot more serological data before long so lets see.
- f38zf5vdt 6y ago
  edit: removed for potentially being misleading.
  - JetSetWilly 6y ago
    Cross-reactivity is an issue in the ELISA test (the actual antibody test). But they validated their results with a second step, the "pseudotype neutralisation assay". This test is highly specific for SARS-CoV-2 - as I understand it, they essentially introduce the virus to the hypothetically immune blood samples and then test that it is indeed neutralised by antibodies. So, I think this Scottish serology test is pretty robust and accounts for these issues with cross-reactivity and specificity of the testing. In addition - they used a control sample from December 2019 none of which tested positive.
    - f38zf5vdt 6y ago
      Yeah, I read more into their assay and I'm inclined to agree with you.
    - tgb 6y ago
      0 out of 100 controls and 6 out of 500 gives a very wide confidence interval. You could easily get those numbers with 1% false positives and no true positives in either group. Is your prior for false positives low enough to rule that out?
      - JetSetWilly 6y ago
        They did two independent assays so I would think the false positives rate should be far below 1% - certainly the authors seem to think so. Secondly if they were false positives, I would expect them to be randomly distributed. Not concentrated in the affluent capital city, and not solely in the second cohort with none in the early march cohort (as you would predict if exponential growth is occurring).
        6y ago
raphlinus 6y ago
Here's an expert thread (for example): https://twitter.com/richardneher/status/1250533354560159745 https://twitter.com/richardneher/status/1250533354560159745

chvid 6y ago

There is a study in Germany done on an outbreak in Heinsberg that has a similar result.

cm2187 6y ago

And also a similar study in Germany with similar results [1]. The result is of course to mechanically reduce the fatality rate to a number close to that of the flu (the problem for hospitals being not so much the fatality rate than the high number of infections), and well within the 0.1-1% range that US health authorities have been advertising for a while. Regarding models, it seems 0.15% is the new basis [2]. Even on the optimistic end of the range (0.1% fatality), with 13k deaths, that's 20% of the UK population infected, a long way from achieving herd immunity. The other thing is that I invite people on hackernews to better control their anxiety. It is not so long ago that pointing that case fatality ratios in jurisdictions that didn't do mass testing and where there seemed to be many unreported cases with mild symptom was overestimating the fatality rate would get you treated of conspirary theorist. South Korea had been measuring a fatality ratio in that range (~0.6%) over a month ago and that was probably already an upper bound (due to not testing 100% of the population). [1] https://mobile.twitter.com/AmeshAA/status/1249446561010106370 https://mobile.twitter.com/AmeshAA/status/124944656101010637... [2] https://mobile.twitter.com/AmeshAA/status/1249020677551796224 https://mobile.twitter.com/AmeshAA/status/124902067755179622...

guscost 6y ago
The people who were treating that hypothesis as an absurd conspiracy theory last month probably won’t own up to it, but I do hope they are reading.
- DanBC 6y ago
  That's not really what those people were saying. It doesn't matter if the number is 5% with a low infection rate, or 0.5% with a very high infection rate: both will lead to very large numbers of dead people unless we take severe action early on. And so far they've been right. Covid-19 is causing huge amounts of excess mortality, even when compared to a really bad flu year.
  - guscost 6y ago
    Source? Europe shows excess mortality spiking to a similar level as the 2017-2018 flu season: https://www.euromomo.eu/ https://www.euromomo.eu/ And that’s with elective procedures being cancelled and everyone scared to go to the hospital for any reason. Here’s some new data indicating that half of the excess mortality in England might not be caused by COVID-19 itself: https://archive.is/2eKCW https://archive.is/2eKCW

loftyal 6y ago

The tests might be inaccurate. Current antibody tests seem to conflate the common cold with covid-19, as they are both coronaviruses. https://edition.cnn.com/2020/04/14/health/coronavirus-antibody-tests-scientists/index.html https://edition.cnn.com/2020/04/14/health/coronavirus-antibo...

JetSetWilly 6y ago
That is not the case for this study, see here for why: https://news.ycombinator.com/item?id=22879363 https://news.ycombinator.com/item?id=22879363
- loftyal 6y ago
  That is good news if that's the case!