Re: Coronavirus - Modelling Aspects Only
Posted: 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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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.
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.
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?
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.
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.
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
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.
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.
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
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).
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
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.
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.
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.
zico wrote:We know the UK prevalence is under 10%