Good luck with the new job. Thanks for all the reports you've done.
I have 2 questions.
1) The ONS report you link to is reporting test positivity. This is not prevalence. The report states:
"The estimates provided in this analysis are for the percentage of the private-residential population testing positive for COVID-19, otherwise known as the positivity rate. We do not report on the prevalence rate. To derive estimates for the prevalence rate instead, we would need to adjust for imperfect tests results. Since we do not have accurate information on the rate of false-positive and false-negative results, we are not providing estimates for prevalence at this time."
Have I missed something in your analysis?
2nd question is related to infection risk. If you test positive then you're infectious for say 5 days. So the chance of having someone in you class who's infectious is much higher then the positivity rate.
2. No, I think it's the other way round. They are doing a snapshot estimate of the proportion of the people who test positive at a particular time, but my point is that not all those people will be infectious - people would typically test PCR positive for 14 days or longer. (The point is that this ONS data is based on random sampling, not on people taking a test when they feel ill)
Thanks for all the posts and tweets! And most of all showing people that one can argue scientifically without getting bound up in personal pride. I have come across other scientists in this space who are the absolute opposite, which is an utterly weird experience. I envy your students (apart from all the learning stuff obviously, once was fine).
Thank you for being the voice of reason throughout Covid- and I’m sorry that it seems that sometimes you might as well bang your head on a brick wall rather than try to get people to engage in questioning their own beliefs and actions.
Good luck with the new job - but I hope you still have time for the odd ‘tweet’ as your little one liners seem to often give me a good giggle! :)
I think your account and your contribution is very important. I am a strong supporter of Prof. Pagel (from ISAGE) and found her article in the BMJ an important 'starter'. I want to suggest 'building bridges'. I have briefly suggested in comment elsewhere that interdisciplinary teams are needed ongoing, pro-bono etc., to examine 'Risk Assessment' (RA) as conducted in the commercial and linked government worlds of 'policy'. My own knowledge of the history of RA is based on my experience previously as a'cog in the machine' in the decades up to 2006. I came to understand by then the very shaky intellectual and evidence base for RA, particularly as it was deployed in the USA and UK. Case histories from early failures in the 1980s to date suggest almost zilch 'Learning from Error' within these cultures. This to my mind points to some deeper, perhaps profound faults that need a depth of study and perhaps a good deal of 'self-analysis'. We are not just talking of pandemics or zoonoses or even of plant diseases.
PS I understood before UK lockdown, to the point of sufficient certainty, the airborne nature of the virus and its context-driven potential explosive dynamic (within the context of doubling times already showing up in unrestricted spread in populations). Like all of us however I fixated (in my case additionally) on sanitising hands etc. I had worked in the past on highly contagious entities in laboratory conditions, so the possibility seemed very plausible. We might, however, go further than personal' reflection now and make a start with that old chestnut, 'the precautionary principle'?
Thank you. But honestly, I've tried building bridges (right back to October 2020 when I offered to help them to do better estimates of the growth rates in their presentations) and I'm afraid it just doesn't work, and that's why I'm frustrated.
Thanks for your reply. Somewhere in this there is a lesson. 😊
Prof Sridhar (Edinburgh, not ISAGE) is emphasising 'prevention' as UK upgrades 'risk' from the oncoming zoonosis. Her contributions to policy during covid were, to my mind, frustratingly (bafflingly?) ineffectual within UK/USA context. Is there a lesson?
I think I am suggesting widening the boundaries outside of 'pandemics' or indeed public health, or social sciences, or data handling/modelling, in the hope that in 'the west' in particular 'the mind set' can get a better take on what we don't know, and on how we think. There are some predicaments out there (I know of no solutions, only responses, to use Hagens' definition) that we seem not to know how to think about?
Thank you! I think sometimes ISAGE and I just agreed to ignore each other (and also some of the time we were probably more or less on the same page, as I'm sure people will tell you), but we seem to need to have a fight about once every six months just for old times' sake
Congratulations on the new job - obviously secondary to your primary role of educating us through your Substacks.
The educational shutdown that made the least sense to me was at universities. You have a cohort with the one of the lowest risks of severe effects, culturally self-isolating from the outside world for 2-3 months at a time, and intensely sociable so able to achieve high levels of shared infection very quickly. And later getting students to all go into isolation every time one tested positive was not much better…
Thanks. And yes, I agree it was a strange one. I think part of the problem is the way that University groups vary so much in size - you can have 400 in a first year lecture or 2 in an Oxbridge tutorial - so trying to come up with policies that can take account of all that is tricky!
Regarding isolation within universities I think it’s not only necessary to think of possible vulnerability of students, but you also have to consider the teaching staff who often might be in a much more vulnerable category. From my personal university teaching experience I have the anecdotal evidence that throughout my career I seemed to experience a period of personal illness immediately following my annual running and teaching on a practical laboratory class series for some 400 medical, veterinary and science students (ironically or not as part of the teaching of infectious diseases to these students). This was in October/November and following the return of students from their summer vacations, and thus a giant mixing pot for all the respiratory infections they may have encountered from travels around the world. We would have 100 students in a laboratory at a time, with 8 supervising members of staff, each half day long practical session repeated 4 times over 2 days and a total of 4 different practicals. From an infection risk perspective it’s clear that the number of potential contacts during such a time is high and thus as I say you need to consider risk for all who participate, students and teachers.
My main concern was actually the social disruption to the building of friendships and developing as people, which I saw first hand with my family. In practice lectures and supervisions could go online during the pandemic (and sadly often still are), but there seemed little reason to stop students socialising amongst themselves. Yes, there were some vulnerable ones - who would have had to isolate anyway in most cases. All hindsight, of course, but the hiatus in crucial personal development could have been avoided.
Yes I take your point and obviously with hindsight we can now evaluate that the policies were in many instances inappropriate and that there were consequences that we didn't give enough weight to. My anecdotal example above was to illustrate that infectious disease risk assessments when some of the risks are of an uncertain magnitude are not straightforward. I consider myself fortunate that I had already retired before COVID19 arose and thus I wasn't put in a position where I needed to make such decisions.
Thank you for all the tweets and posts; all the best with the new job.
Thank you!
Hi Oliver
Good luck with the new job. Thanks for all the reports you've done.
I have 2 questions.
1) The ONS report you link to is reporting test positivity. This is not prevalence. The report states:
"The estimates provided in this analysis are for the percentage of the private-residential population testing positive for COVID-19, otherwise known as the positivity rate. We do not report on the prevalence rate. To derive estimates for the prevalence rate instead, we would need to adjust for imperfect tests results. Since we do not have accurate information on the rate of false-positive and false-negative results, we are not providing estimates for prevalence at this time."
Have I missed something in your analysis?
2nd question is related to infection risk. If you test positive then you're infectious for say 5 days. So the chance of having someone in you class who's infectious is much higher then the positivity rate.
Am I missing something in your calculations?
1. I would say that they are technically right, that test positivity and prevalence aren't exactly the same, but I think for these kinds of purposes they are close enough that it doesn't really matter, for PCR testing at least. This report https://www.gov.uk/government/publications/gos-impact-of-false-positives-and-negatives-3-june-2020/impact-of-false-positives-and-false-negatives-in-the-uks-covid-19-rt-pcr-testing-programme-3-june-2020 talks about false negative and positive rates being less than 5%, and I think false positive rates are much lower than that (say 0.05% or lower).
2. No, I think it's the other way round. They are doing a snapshot estimate of the proportion of the people who test positive at a particular time, but my point is that not all those people will be infectious - people would typically test PCR positive for 14 days or longer. (The point is that this ONS data is based on random sampling, not on people taking a test when they feel ill)
And best wishes from me with your new job. You've been an oasis of sanity and good humour over the last few years.
Thank you so much!
Thanks for all the posts and tweets! And most of all showing people that one can argue scientifically without getting bound up in personal pride. I have come across other scientists in this space who are the absolute opposite, which is an utterly weird experience. I envy your students (apart from all the learning stuff obviously, once was fine).
Thank you so much for saying that, it means a huge amount!
Thank you for being the voice of reason throughout Covid- and I’m sorry that it seems that sometimes you might as well bang your head on a brick wall rather than try to get people to engage in questioning their own beliefs and actions.
Good luck with the new job - but I hope you still have time for the odd ‘tweet’ as your little one liners seem to often give me a good giggle! :)
Thank you very much. I'm not expecting to have a lot of time, but I'll see how it goes!
Re 'Learning from Error' and 'Covid'.
I think your account and your contribution is very important. I am a strong supporter of Prof. Pagel (from ISAGE) and found her article in the BMJ an important 'starter'. I want to suggest 'building bridges'. I have briefly suggested in comment elsewhere that interdisciplinary teams are needed ongoing, pro-bono etc., to examine 'Risk Assessment' (RA) as conducted in the commercial and linked government worlds of 'policy'. My own knowledge of the history of RA is based on my experience previously as a'cog in the machine' in the decades up to 2006. I came to understand by then the very shaky intellectual and evidence base for RA, particularly as it was deployed in the USA and UK. Case histories from early failures in the 1980s to date suggest almost zilch 'Learning from Error' within these cultures. This to my mind points to some deeper, perhaps profound faults that need a depth of study and perhaps a good deal of 'self-analysis'. We are not just talking of pandemics or zoonoses or even of plant diseases.
PS I understood before UK lockdown, to the point of sufficient certainty, the airborne nature of the virus and its context-driven potential explosive dynamic (within the context of doubling times already showing up in unrestricted spread in populations). Like all of us however I fixated (in my case additionally) on sanitising hands etc. I had worked in the past on highly contagious entities in laboratory conditions, so the possibility seemed very plausible. We might, however, go further than personal' reflection now and make a start with that old chestnut, 'the precautionary principle'?
Thank you. But honestly, I've tried building bridges (right back to October 2020 when I offered to help them to do better estimates of the growth rates in their presentations) and I'm afraid it just doesn't work, and that's why I'm frustrated.
Thanks for your reply. Somewhere in this there is a lesson. 😊
Prof Sridhar (Edinburgh, not ISAGE) is emphasising 'prevention' as UK upgrades 'risk' from the oncoming zoonosis. Her contributions to policy during covid were, to my mind, frustratingly (bafflingly?) ineffectual within UK/USA context. Is there a lesson?
I think I am suggesting widening the boundaries outside of 'pandemics' or indeed public health, or social sciences, or data handling/modelling, in the hope that in 'the west' in particular 'the mind set' can get a better take on what we don't know, and on how we think. There are some predicaments out there (I know of no solutions, only responses, to use Hagens' definition) that we seem not to know how to think about?
Thank you for everything. I’ve learned a great deal from you and enjoyed all of it. Wishing you continued success!
Thank you for reading!
Thank you Oliver. You are right, you know. Plus impossible to say how much a sensible take, with a clear explanation, meant at the time.
Thank you, that means a huge amount to hear
As always a good read and points well put.
I often felt during Covid isage didn’t challenge you as it was hard to argue against.
Best wishes for your new role (you don’t need luck, you’ll smash it) and hopefully you’ll find time for the odd piece.
Thank you! I think sometimes ISAGE and I just agreed to ignore each other (and also some of the time we were probably more or less on the same page, as I'm sure people will tell you), but we seem to need to have a fight about once every six months just for old times' sake
Thanks for all your thoughtful and well argued contributions, here and on Twitter, and I hope that all goes well in your new role as HoS.
Thank you - I'm looking forward to getting stuck in now!
Good luck in your new role..... you've been a revelation
Thank you!
Congratulations on the new job - obviously secondary to your primary role of educating us through your Substacks.
The educational shutdown that made the least sense to me was at universities. You have a cohort with the one of the lowest risks of severe effects, culturally self-isolating from the outside world for 2-3 months at a time, and intensely sociable so able to achieve high levels of shared infection very quickly. And later getting students to all go into isolation every time one tested positive was not much better…
Thanks. And yes, I agree it was a strange one. I think part of the problem is the way that University groups vary so much in size - you can have 400 in a first year lecture or 2 in an Oxbridge tutorial - so trying to come up with policies that can take account of all that is tricky!
Regarding isolation within universities I think it’s not only necessary to think of possible vulnerability of students, but you also have to consider the teaching staff who often might be in a much more vulnerable category. From my personal university teaching experience I have the anecdotal evidence that throughout my career I seemed to experience a period of personal illness immediately following my annual running and teaching on a practical laboratory class series for some 400 medical, veterinary and science students (ironically or not as part of the teaching of infectious diseases to these students). This was in October/November and following the return of students from their summer vacations, and thus a giant mixing pot for all the respiratory infections they may have encountered from travels around the world. We would have 100 students in a laboratory at a time, with 8 supervising members of staff, each half day long practical session repeated 4 times over 2 days and a total of 4 different practicals. From an infection risk perspective it’s clear that the number of potential contacts during such a time is high and thus as I say you need to consider risk for all who participate, students and teachers.
My main concern was actually the social disruption to the building of friendships and developing as people, which I saw first hand with my family. In practice lectures and supervisions could go online during the pandemic (and sadly often still are), but there seemed little reason to stop students socialising amongst themselves. Yes, there were some vulnerable ones - who would have had to isolate anyway in most cases. All hindsight, of course, but the hiatus in crucial personal development could have been avoided.
Yes I take your point and obviously with hindsight we can now evaluate that the policies were in many instances inappropriate and that there were consequences that we didn't give enough weight to. My anecdotal example above was to illustrate that infectious disease risk assessments when some of the risks are of an uncertain magnitude are not straightforward. I consider myself fortunate that I had already retired before COVID19 arose and thus I wasn't put in a position where I needed to make such decisions.