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Coronavirus - modelling aspects only please

Scientific discovery and discussion
johnhemming
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Re: Coronavirus - modelling aspects only please

#332315

Postby johnhemming » August 11th, 2020, 4:27 am

I refer you to my previous comments. If someone is not susceptible they dont get infected and cannot be counted as part of the IFR denominator.

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Re: Coronavirus - modelling aspects only please

#332358

Postby tjh290633 » August 11th, 2020, 10:10 am

johnhemming wrote:I refer you to my previous comments. If someone is not susceptible they dont get infected and cannot be counted as part of the IFR denominator.

OK, so they tell us that there have been 112,000 test with 25 positive results. Does that mean that the 111,975 do not get counted?

TJH

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Re: Coronavirus - modelling aspects only please

#332366

Postby johnhemming » August 11th, 2020, 10:29 am

That is a different issue.

The Infection Fatality Rate is the proportion of people who are infected that die. That is calculated by (dead people from the virus)/(total number of infections)

If someone is not susceptible they don't catch the disease so cannot appear in the (total number of infections)

Itsallaguess
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Re: Coronavirus - modelling aspects only please

#333066

Postby Itsallaguess » August 14th, 2020, 5:54 am

An article on the BBC site this morning talks about how the recent rises in UK cases, generally and also particularly in the various local hot-spots that have sprung up in recent weeks, doesn't seem to be driving a subsequent requirement for hospital admissions, and isn't being passed through into a corresponding rise in the number of deaths from the virus -

It may still be too soon for any increase in infections to translate into more people in hospital or dying with Covid-19 nationally.

But hotspots can test the theory since their numbers of cases started to increase earlier.

Leicester saw worsening infection figures throughout the early summer before Health Secretary Matt Hancock announced a local lockdown at the end of the June.

And Blackburn overtook Leicester as the part of the country with the highest rate of infection in July. Data released on Thursday by NHS England showed that rising cases were not matched by an increase in the number of people in hospital in the NHS trusts that serve either of these councils.

The number of people admitted to hospital for the first time with Covid-19 did increase in Leicester in June, but the rise was much smaller than the rise in confirmed cases.

In July, Leicester saw 1,336 cases but only seven people were admitted to hospital with Covid-19.

In Blackburn, the number of infections more than doubled in July, but the number of people admitted to hospital fell from 54 in June to 13 in July.

More of the cases now being detected nationally are in people aged 15-44.

They are much less likely to become seriously ill or die with coronavirus.


https://www.bbc.co.uk/news/health-53772459

Continuing to shield the more vulnerable sections of society whilst allowing herd-immunity to build up in those large sections that are much less susceptible to the worst symptoms of Covid-19 looks to me to be the best chance we've got, in the absence of a proven vaccine, of allowing the UK economy to build back up whilst still protecting the most vulnerable, and at the same time protecting the NHS from being overwhelmed by those 'most-vulnerable' cases..

Cheers,

Itsallaguess

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Re: Coronavirus - modelling aspects only please

#333291

Postby zico » August 14th, 2020, 7:39 pm

The government has decided to change the definition of a Covid-19 death in England. Previously it was anyone dying who had previously tested positive for Covid-19, no matter how long ago they tested positive. They are now using a definition of death being within 28 days of a positive Covid-19, with a subsidiary definition of 60 days since a positive test.

The change in definition has reduced the reported number of deaths by 5,400 with the difference only kicking in for July & August (because earlier deaths were almost entirely within 28 days of testing positive).

I've had a look at estimating the death rate for the sub-group of people who tested positive but died more than 28 days later.
There are 4,300 deaths for this category. In total, there have been 273,000 positive tests of which 40,000 have died - giving 233,000 positive cases.

The death rate for this sub-group = 4,300/233,00 = 2.33% over a period of 2 months, which equates to a 14% death rate per annum.
For comparison, the normal death rate for people aged 85-89 is 9.7% and the normal death rate for people aged 90+ is 19.1%.

So if you test positive for Covid-19, even if you survive the first 28 days, your expected death rate is higher than people aged 85-89 years old.
ONS figures show the % rate of positive cases does NOT vary by age groups.
If positive cases after 28 days have fully recovered from the virus, you'd expect them to have the same death rate as the general population - about 1% per annum. But they are dying at over 9 times that rate.

It's very clear that people with a positive test have a much higher chance than average of dying, even if they survive the first 28 days.



A graphical view of the effects of the changes in definition.

https://www.cebm.net/covid-19/public-he ... a-revised/

ONS report showing infection rates are similar across all age groups.

https://www.ons.gov.uk/peoplepopulation ... udy-period

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Re: Coronavirus - modelling aspects only please

#333379

Postby Itsallaguess » August 15th, 2020, 10:53 am

Looking at the relatively low, but steadily rising UK case-numbers, I wondered if others thought we might avoid the harshness of earlier lock-downs, so long as the numbers of deaths from the virus remains so stubbornly low -

Image

Image source - https://www.worldometers.info/coronavirus/country/uk/

Has the UK reached the point where many people wanted to get to anyway, where so long as those most vulnerable are taking stronger precautions themselves, and allowing those that are much less susceptible to the worst outcomes of a Covid infections to continue to get infected, then the benefits to the economy of allowing that situation to steadily progress might be the 'least-worst' sweet-spot whilst we all await a hoped-for vaccine?

Such an approach also, of course, might well turn out to help with any growing 'herd-immunity' that we might end up needing if such a vaccine takes much longer to develop, or doesn't emerge at all...

That's not to say, of course, that local hot-spots might well continue to be acted on with more ferocity, but I'm asking this question in more general terms, really...

Cheers,

Itsallaguess

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Re: Coronavirus - modelling aspects only please

#333381

Postby dealtn » August 15th, 2020, 10:58 am

zico wrote:

If positive cases after 28 days have fully recovered from the virus, you'd expect them to have the same death rate as the general population - about 1% per annum. But they are dying at over 9 times that rate.




You wouldn't expect that, statistics aren't that easy!

They might be likely to have the same death rate as those that have recovered from viral infections. Or if, as part of their treatment they required being put on a ventilator or having surgery, their expectation would be in line with others that have been on ventilators, or had recent surgery, for instance. That is a lot different to the same death rate as the general population.

They might also be part of a riskier subset of the general population too, For instance diabetic, prone to infection, only one lung etc. To illustrate with an example if it isn't intuitive. Consider the population of people recently discharged from A&E with a broken leg as a sample you want to analyse. Now if 50% of those are motorbike riders, but only 10% of the "general population" ride a motor bike, and you then do an analysis of those visiting an A&E for the second time within 6 months of being discharged with a broken leg you are looking at a subset of people undertaking risky activity (motorbike riding), distorting the picture where 90% of the "general population" don't ride bikes.

It is possible that someone who doesn't ride a motorbike will break a leg, then a few weeks later falls off a kerb and breaks an arm, of course. But a motorbike rider breaking a leg, and then having a second A&E visit (be that bike related or not) is a different risk percentage.

Now whether that is enough to explain a 9 fold difference is another matter entirely, and I don't have that answer, but what you claim doesn't follow I'm afraid as simply as you think.

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Re: Coronavirus - modelling aspects only please

#333388

Postby Itsallaguess » August 15th, 2020, 11:31 am

Itsallaguess wrote:
Has the UK reached the point where many people wanted to get to anyway, where so long as those most vulnerable are taking stronger precautions themselves, and allowing those that are much less susceptible to the worst outcomes of a Covid infections to continue to get infected, then the benefits to the economy of allowing that situation to steadily progress might be the 'least-worst' sweet-spot whilst we all await a hoped-for vaccine?


Apologies for replying to my own post, but I've just read this interesting analysis in the Telegraph this morning, that seems to confirm that the current cases are mostly within the age ranges with the least risk of major issues from the virus -

The recent spikes of coronavirus cases in localised areas around the UK are unlikely to lead to more deaths, the latest NHS Test and Trace data suggests.

New charts showing the age range of those testing positive for the virus in hotspot areas such as Blackburn with Darwen, Oldham, Leicester and Bradford, reveal that the vast majority of those impacted are under 65.

In contrast, large numbers of older people were testing positive at the height of the pandemic. The age difference matters because older people are far more likely to be hospitalised and to die from the virus.

And there is evidence that the death rate from Covid-19 has been falling steadily since March, when it was around six per cent overall. It is now around one per cent.

Professor Francois Balloux, of UCL, said the effect could be due to improved treatment and also a "mortality displacement" effect after many at-risk people died in the first wave. Prof Balloux believes that may reduce the number of deaths in the event of a second wave (see potential scenarios below).


More here, in the pay-walled Telegraph article itself -

https://www.telegraph.co.uk/news/2020/08/14/analysis-local-spikes-unlikely-lead-coronavirus-deaths/

Cheers,

Itsallaguess

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Re: Coronavirus - modelling aspects only please

#333389

Postby zico » August 15th, 2020, 11:33 am

dealtn wrote:
zico wrote:

If positive cases after 28 days have fully recovered from the virus, you'd expect them to have the same death rate as the general population - about 1% per annum. But they are dying at over 9 times that rate.




You wouldn't expect that, statistics aren't that easy!

They might be likely to have the same death rate as those that have recovered from viral infections. Or if, as part of their treatment they required being put on a ventilator or having surgery, their expectation would be in line with others that have been on ventilators, or had recent surgery, for instance. That is a lot different to the same death rate as the general population.

They might also be part of a riskier subset of the general population too, For instance diabetic, prone to infection, only one lung etc. To illustrate with an example if it isn't intuitive. Consider the population of people recently discharged from A&E with a broken leg as a sample you want to analyse. Now if 50% of those are motorbike riders, but only 10% of the "general population" ride a motor bike, and you then do an analysis of those visiting an A&E for the second time within 6 months of being discharged with a broken leg you are looking at a subset of people undertaking risky activity (motorbike riding), distorting the picture where 90% of the "general population" don't ride bikes.

It is possible that someone who doesn't ride a motorbike will break a leg, then a few weeks later falls off a kerb and breaks an arm, of course. But a motorbike rider breaking a leg, and then having a second A&E visit (be that bike related or not) is a different risk percentage.

Now whether that is enough to explain a 9 fold difference is another matter entirely, and I don't have that answer, but what you claim doesn't follow I'm afraid as simply as you think.


Yes, fair points, and good timing, as I was just about to post my updated calculations, using hospitalised data.

In England there have been 233,000 positive cases (excluding those who died within 28 days).
73,000 positive cases were hospitalised, and didn't die within 28 days.
So there's 160,000 cases which weren't hospitalised. It seems reasonable to assume these cases would have the same death rate as the average population. (These cases will include for example, medical staff testing positive but not developing symptoms)
160,000 * 1% (2 mths /12 mths ) = 266 deaths expected from positive cases not hospitalised.
These 266 will die randomly from heart attacks, hit by buses etc and their deaths will have nothing to do with their positive Covid-19 test.

Excluding these 266 means the remaining 29+ days deaths come from hospitalised cases.
Deaths from hospitalised cases over 28 days after positive test = 4,300- 266 = 4,034
Death rate = 4,034/73,000 = 5.5% in 2 months (equating to 33% per year). (For comparison, 80-85 year old mortality rate is 5.2% - but per year, not per month)

This makes them almost twice as likely to die as the 90+ years age group death rate of 19%.

A couple of points. It's likely that the age profile of the "positive cases not hospitalised" group would be lower than the average age - if so, that would give expected deaths of lower than 266 deaths, but it's not that important a number.
Conversely, the hospitalised group than "recovered" (A.k.a - survived more than 28 days) are likely to be an older age profile, as Covid-19 is more likely to be serious for older people. Even so, a death rate of 33% is very high. "What doesn't kill you makes you stronger" really doesn't apply to this group.

Finally, the excess deaths figure is still the best measure of all, and stands at 57,749 for England.
(Assuming the average Covid-19 death means people die about 10 years earlier than they otherwise would have done, we'd expect the weekly death tolls to be 110 lower than they otherwise would have been - because those 57,000 deaths won't now be occuring at a rate of 5,700 per year, or 110 per week.)

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Re: Coronavirus - modelling aspects only please

#333396

Postby Mike4 » August 15th, 2020, 11:50 am

dealtn wrote:
zico wrote:

If positive cases after 28 days have fully recovered from the virus, you'd expect them to have the same death rate as the general population - about 1% per annum. But they are dying at over 9 times that rate.




You wouldn't expect that, statistics aren't that easy!

They might be likely to have the same death rate as those that have recovered from viral infections. Or if, as part of their treatment they required being put on a ventilator or having surgery, their expectation would be in line with others that have been on ventilators, or had recent surgery, for instance. That is a lot different to the same death rate as the general population.

They might also be part of a riskier subset of the general population too, For instance diabetic, prone to infection, only one lung etc. To illustrate with an example if it isn't intuitive. Consider the population of people recently discharged from A&E with a broken leg as a sample you want to analyse. Now if 50% of those are motorbike riders, but only 10% of the "general population" ride a motor bike, and you then do an analysis of those visiting an A&E for the second time within 6 months of being discharged with a broken leg you are looking at a subset of people undertaking risky activity (motorbike riding), distorting the picture where 90% of the "general population" don't ride bikes.

It is possible that someone who doesn't ride a motorbike will break a leg, then a few weeks later falls off a kerb and breaks an arm, of course. But a motorbike rider breaking a leg, and then having a second A&E visit (be that bike related or not) is a different risk percentage.

Now whether that is enough to explain a 9 fold difference is another matter entirely, and I don't have that answer, but what you claim doesn't follow I'm afraid as simply as you think.


I would have thought something that goes part way to explaining it is the erroneous concept that all people either die of COVID, or get better. They don't, there is a third option. Something like one third of people diagnosed with COVID-19 apparently remain ill with long term sequelae, sometimes serious, and their new COVID-inspired long term heart conditions, liver damage, lung damage, kidney damage, nerve damage etc etc would seem likely to come and get them sooner than if they'd never had the COVID.

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Re: Coronavirus - modelling aspects only please

#333398

Postby zico » August 15th, 2020, 11:51 am

Itsallaguess wrote:
Itsallaguess wrote:
Has the UK reached the point where many people wanted to get to anyway, where so long as those most vulnerable are taking stronger precautions themselves, and allowing those that are much less susceptible to the worst outcomes of a Covid infections to continue to get infected, then the benefits to the economy of allowing that situation to steadily progress might be the 'least-worst' sweet-spot whilst we all await a hoped-for vaccine?


Apologies for replying to my own post, but I've just read this interesting analysis in the Telegraph this morning, that seems to confirm that the current cases are mostly within the age ranges with the least risk of major issues from the virus -

The recent spikes of coronavirus cases in localised areas around the UK are unlikely to lead to more deaths, the latest NHS Test and Trace data suggests.

New charts showing the age range of those testing positive for the virus in hotspot areas such as Blackburn with Darwen, Oldham, Leicester and Bradford, reveal that the vast majority of those impacted are under 65.

In contrast, large numbers of older people were testing positive at the height of the pandemic. The age difference matters because older people are far more likely to be hospitalised and to die from the virus.

And there is evidence that the death rate from Covid-19 has been falling steadily since March, when it was around six per cent overall. It is now around one per cent.

Professor Francois Balloux, of UCL, said the effect could be due to improved treatment and also a "mortality displacement" effect after many at-risk people died in the first wave. Prof Balloux believes that may reduce the number of deaths in the event of a second wave (see potential scenarios below).


More here, in the pay-walled Telegraph article itself -

https://www.telegraph.co.uk/news/2020/08/14/analysis-local-spikes-unlikely-lead-coronavirus-deaths/

Cheers,

Itsallaguess


I think it's far more difficult now to draw conclusions from the testing figures because of the local lockdowns and increased testing in high-risk areas.
I really really don't want to sound like Donald Trump "Testing is causing cases. If we didn't test the virus would go away" but it's a fact that if you carry out proportionately more testing in areas which you think are high-risk, you will find a lot more cases and higher % of positive cases than if you test randomly, or just test people who present with symptoms.

Testing people in the high-risk areas of garment factories and meat-packing plants means that a higher proportion of mild cases are picked up, and also, because workers are being tested, they'll have a younger age range.

All these above factors mean that unfortunately, the figures don't give us much of a clue about what's going on at the moment, though it is likely that the recent increase in positive cases is down to better targeting of high-risk groups, rather than being a genuine increase in infections.

In the USA there was a similar view that primarily younger people were getting infected in their second wave, so there wouldn't be a problem with deaths, but their deaths have surged to over 1,000 per day.

My personal view (but it's just a view, with no back-up evidence) is that the "Eat Out to Help Out" scheme is going to fuel a nationwide rise in cases, particularly amongst 60+ age group, because cafes and restaurants are full 3 days a week, with lots of different groups of people not wearing masks indoors, and being in that environment for 1-2 hours, because the staff are rushed off their feet and there are long delays. Science has shown that large groups of people indoors for hours is a good way to spread the disease, but whether social distancing between tables will be enough to stop the spread is something we'll be finding out in the coming weeks and months.
I am slightly hopeful for the future as so far, positive cases have stayed quite low over the past few weeks.

I've had a go at calculating the UK "mortality displacement" effect in my earlier post, which doesn't appear to be significant. I think a more likely explanation is that earlier Covid-19 sufferers had higher viral loads, because nobody was social distancing in early March.

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Re: Coronavirus - modelling aspects only please

#333402

Postby johnhemming » August 15th, 2020, 12:01 pm

zico wrote:My personal view (but it's just a view, with no back-up evidence) is that the "Eat Out to Help Out" scheme is going to fuel a nationwide rise in cases, particularly amongst 60+ age group, because cafes and restaurants are full 3 days a week, with lots of different groups of people not wearing masks indoors, and being in that environment for 1-2 hours, because the staff are rushed off their feet and there are long delays. Science has shown that large groups of people indoors for hours is a good way to spread the disease, but whether social distancing between tables will be enough to stop the spread is something we'll be finding out in the coming weeks and months.
I am slightly hopeful for the future as so far, positive cases have stayed quite low over the past few weeks.

We will know about this when we get the hospital admissions for next week. It takes 13/14 days before someone gets admitted after catching the infection (if it is serious enough). Hence the first admissions would be Sunday/Monday and we should see those figures by the end of next week or the week afterwards.

These figures for England
https://coronavirus.data.gov.uk/healthc ... me=England

Have shown no tick up so far following the relaxations so far.

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Re: Coronavirus - modelling aspects only please

#333404

Postby Itsallaguess » August 15th, 2020, 12:19 pm

zico wrote:
My personal view (but it's just a view, with no back-up evidence) is that the "Eat Out to Help Out" scheme is going to fuel a nationwide rise in cases, particularly amongst 60+ age group, because cafes and restaurants are full 3 days a week, with lots of different groups of people not wearing masks indoors, and being in that environment for 1-2 hours, because the staff are rushed off their feet and there are long delays.

Science has shown that large groups of people indoors for hours is a good way to spread the disease, but whether social distancing between tables will be enough to stop the spread is something we'll be finding out in the coming weeks and months.

I am slightly hopeful for the future as so far, positive cases have stayed quite low over the past few weeks.


To be fair, there's been lots of predictions of imminent case-surges, right back to the BLM protests, the shops re-opening, the beaches being 'crammed' (nice zoomed camera angles lads...), and of course those pesky virus-laden, non-social-distanced, mask-less pubs that have been open for weeks now, so I'm not sure that the 'Eat Out to Help Out' schemes are likely to be as big a source of widespread cases as you might think, and that's especially so given that in my experience, having eaten out a number of times in recent weeks at a number of different places, and also reading anecdotally about the processes elsewhere, the places people are eating in are taking stringent records of customer visits and contact details, so even small outbreaks should be relatively manageable, I would hope.

Cheers,

Itsallaguess

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Re: Coronavirus - modelling aspects only please

#333411

Postby zico » August 15th, 2020, 12:51 pm

Itsallaguess wrote:
To be fair, there's been lots of predictions of imminent case-surges, right back to the BLM protests, the shops re-opening, the beaches being 'crammed' (nice zoomed camera angles lads...), and of course those pesky virus-laden, non-social-distanced, mask-less pubs that have been open for weeks now, so I'm not sure that the 'Eat Out to Help Out' schemes are likely to be as big a source of widespread cases as you might think, and that's especially so given that in my experience, having eaten out a number of times in recent weeks at a number of different places, and also reading anecdotally about the processes elsewhere, the places people are eating in are taking stringent records of customer visits and contact details, so even small outbreaks should be relatively manageable, I would hope.

Cheers,

Itsallaguess


Yes, you're right in that the media likes a nice bit of drama, so they scaremonger about beaches even though outdoor transmission is far less likely, so beaches are much less risk. We've eaten out a few times recently, picking our places carefully and going in at opening time, and been comfortable doing so except for 1 time when we ate indoors. I've also seen a lot of places (from the outside) that have been just crammed with elderly people. It's all a question of percentages, if less than X% of people ignore regulations, that's not a big problem, but more than Y% of people ignoring rules and the virus spreads again.

One bugbear of mine is the constant reference to infection "spikes". Exponential growth doesn't work like that, it's like ivy "first it sleeps, then it creeps, then it leaps". You get 1 case, 2, 4, 8, 16, 32, 64, 128, 256, 512 and if you only check when the numbers are 512, it looks like a spike, but it's just that you didn't check earlier. When numbers are growing, it doesn't look like a big problem until it's too late.

The best guide we have as to the future is the EU, as it comprises countries like us, but were earlier to lockdown and earlier to start lifting lockdown. They are showing a slow but steady increase in cases, with the 7-day rolling average being 50% higher than 2 weeks ago, and 3 times higher than their lowest rates in early-July (source FT Coronavirus latest - https://ig.ft.com/coronavirus-chart/?ar ... lues=cases). The EU experience is that cases reduced when lockdown was first lifted, but then started to gradually increase. In the short-term, I reckon the UK may do a bit better than the EU because we will have had much less influx of holidaymakers from different regions of the EU.
The challenge for all countries is keeping the rate of increase under control until a vaccine appears (though even then I saw a report that said vaccines are typically only 60% effective).

I'm still fairly pessimistic, but really hope I'm wrong and you're right!

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Re: Coronavirus - modelling aspects only please

#333420

Postby Itsallaguess » August 15th, 2020, 1:15 pm

zico wrote:
The best guide we have as to the future is the EU, as it comprises countries like us, but were earlier to lockdown and earlier to start lifting lockdown.

They are showing a slow but steady increase in cases, with the 7-day rolling average being 50% higher than 2 weeks ago, and 3 times higher than their lowest rates in early-July (source FT Coronavirus latest - https://ig.ft.com/coronavirus-chart/?ar ... lues=cases).

The EU experience is that cases reduced when lockdown was first lifted, but then started to gradually increase. In the short-term, I reckon the UK may do a bit better than the EU because we will have had much less influx of holidaymakers from different regions of the EU.

The challenge for all countries is keeping the rate of increase under control until a vaccine appears (though even then I saw a report that said vaccines are typically only 60% effective).


But that's the point I was trying to make - in your post above, you're still concentrating on 'cases', and I'm trying to ask if, given the recent gradual rise in 'cases' hasn't yet 'passed through' into a subsequent rise in 'deaths', that there will perhaps now grow to be less of a direct focus where previously 'case-numbers' drove policy, and where 'persistently-low deaths' might now gradually start to inform policy in a greater way going forward, whilst 'allowing' a rise in acceptable cases, given that they are not causing the same problems to the health services that previous waves did...

Cheers,

Itsallaguess

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Re: Coronavirus - modelling aspects only please

#333424

Postby zico » August 15th, 2020, 1:31 pm

Itsallaguess wrote:
But that's the point I was trying to make - in your post above, you're still concentrating on 'cases', and I'm trying to ask if, given the recent gradual rise in 'cases' hasn't yet 'passed through' into a subsequent rise in 'deaths', that there will perhaps now grow to be less of a direct focus where previously 'case-numbers' drove policy, and where 'persistently-low deaths' might now gradually start to inform policy in a greater way going forward, whilst 'allowing' a rise in acceptable cases, given that they are not causing the same problems to the health services that previous waves did...

Cheers,

Itsallaguess


We have evidence from the USA which lifted restrictions early, had an initial surge in cases, and after the inevitable lag, these increased cases are now causing an increase in deaths. There may well be promising signs that the death rate is reducing, which we would expect because doctors are getting better at finding out for a new disease what works, and what doesn't - for example, it's clear that ventilators were over-used at the start of the outbreak.

As you say, there's more to it than simply looking at cases, and there's also more to it than simply looking at deaths, because there are worrying signs that Covid-19 causes more lasting damage than first thought. I've shown that positive cases surviving after 28 days have a 33% annual death rate, so seems pretty clear at least to me that their deaths are being caused by the virus.

The problem with waiting for an uptick in deaths before taking action is that it's then far too late and will cost many additional lives if the virus is still just as dangerous. When faced with a choice between actual evidence of the death rate or a hypothesis about the death rate being lower in future, it's a pretty clear and obvious choice to me.

For me the Daily Telegraph has lost credibility as a source because it has been consistently arguing various hypotheses about Covid-19, but everything they've published argues that it isn't so bad and we shouldn't worry too much - there is simply no balance to it at all.

According to the Telegraph
- we didn't need lockdown
- we wouldn't get a lot of deaths in the UK
- we might have already achieved herd immunity
- we didn't need to keep lockdown as long as we have done
- we need to get back to working in offices
- lockdown will cost 200,000 lives.
- mask-wearing shouldn't be enforced because there was no need
- a vaccine will be available by September
- children can't spread the virus.
I'm sure there are a lot more similar articles in similar vein that I can't recall.

I'm not saying we should ignore the Telegraph articles, but it is important to look at the actual research they mention, rather than depending on the Telegraph writers' take on it.

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Re: Coronavirus - modelling aspects only please

#333426

Postby Mike4 » August 15th, 2020, 1:41 pm

zico wrote:We have evidence from the USA which lifted restrictions early, had an initial surge in cases, and after the inevitable lag, these increased cases are now causing an increase in deaths. There may well be promising signs that the death rate is reducing, which we would expect because doctors are getting better at finding out for a new disease what works, and what doesn't - for example, it's clear that ventilators were over-used at the start of the outbreak. However, there are worrying signs that Covid-19 causes more lasting damage than first thought.


Another hypothesis is the cause of the missing deaths whilst infections are rising, is that nearly 50% of people being tested positive
on both sides of the pond are under 30 years old. No-one is sure why yet but ideas are that the under-30s rarely get particularly ill with it (if at all all), and that the most susceptible people have all had it now and either died or developed immunity. Another idea is the herd immunity threshold is a lot lower than we first thought although I'd say this would show up as a reduction in infection rate before death rate, not the other way around that we are seeing.

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Re: Coronavirus - modelling aspects only please

#333428

Postby zico » August 15th, 2020, 1:56 pm

Mike4 wrote:Another hypothesis is the cause of the missing deaths whilst infections are rising, is that nearly 50% of people being tested positive
on both sides of the pond are under 30 years old. No-one is sure why yet but ideas are that the under-30s rarely get particularly ill with it (if at all all), and that the most susceptible people have all had it now and either died or developed immunity. Another idea is the herd immunity threshold is a lot lower than we first thought although I'd say this would show up as a reduction in infection rate before death rate, not the other way around that we are seeing.


We know that younger people are now more likely to mingle, because they see the virus as something that is only serious for older people (quite a reasonable evidence-based viewpoint) so you'd expect that a larger proportion of younger people are going to develop symptoms. It's important to remember that the Chinese whistle-blower doctor who died was fairly young and with no previous medical conditions, so if young people are partying like they are immune, they're more likely to catch higher doses of the virus. If I was under 30 years old, I'd have a very different approach to personal risk of Covid-19 infection.

As for herd immunity, the previously accepted scientific wisdom was that it kicked in around 70%, and even the proponents of lower herd immunity figures aren't saying it's less than 20%. We know the UK prevalence is under 10% so it seems vanishingly unlikely we're anywhere near herd immunity levels. As I've suggested before, the (mostly) right-wing libertarians proposing these ideas should offer to have a party with infected people in a very small space so we can see whether they are right, and only 20% actually catch the virus. Unsurprisingly, no young right-wing journalists have offered to help science in this way. However, there have been a few tragic reports of young people in USA deliberately holding parties to prove Covid is just a hoax, and they saw infection levels of 50% + and some deaths as a result.

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Re: Coronavirus - modelling aspects only please

#333429

Postby johnhemming » August 15th, 2020, 2:00 pm

zico wrote:We have evidence from the USA which lifted restrictions early, had an initial surge in cases, and after the inevitable lag, these increased cases are now causing an increase in deaths.

I have not studied in the USA in a lot of detail, but my impression is that those areas which had a substantial initial wave are not having a second wave. This, of course, is symptomatic of having hit herd immunity.

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Re: Coronavirus - modelling aspects only please

#333434

Postby Mike4 » August 15th, 2020, 2:18 pm

zico wrote:We know the UK prevalence is under 10%


Thanks for your reply and I agree with most of it, except this.

Dr John Campbell did an article on this about a month ago and cited a number of studies he found on this subject, with wildly differing answers. 10% being at the low end of the range, and 80% at the upper IIRC.

The only conclusion one could draw was if anyone was brave enough to claim a definite figure (e.g. 10%), Dr John's article gives a study which proves them wrong!


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