Coronavirus - Modelling Aspects Only

[johnhemming]

There are various figures I disagree with.

Firstly, susceptibility is not 100%. We don't know what figure it is. The only test on immunity found 50% resistance, but the test was only on 18 people and not in the UK. It was clear that for a lot of people the virus is not an issue.

Secondly, the most recent figure from CDC in USA on IFR was 0.26%. Now it is not entirely clear whether that is of the susceptible population or not. I think somewhere in the range of 0.1 - 0.2% is likely.

Thirdly, there is a developing body of evidence that the virus was active in the UK earlier than is thought.

Hence a lot of the figures the government are relying upon are wrong.

[zico]

There are various figures I disagree with.

Firstly, susceptibility is not 100%. We don't know what figure it is. The only test on immunity found 50% resistance, but the test was only on 18 people and not in the UK. It was clear that for a lot of people the virus is not an issue.

Secondly, the most recent figure from CDC in USA on IFR was 0.26%. Now it is not entirely clear whether that is of the susceptible population or not. I think somewhere in the range of 0.1 - 0.2% is likely.

Thirdly, there is a developing body of evidence that the virus was active in the UK earlier than is thought.

Hence a lot of the figures the government are relying upon are wrong.

Susceptibility is irrelevant for these scenarios, unless assuming that fewer than 20% of UK adult population can be susceptible - no data for this that I'm aware.

On the IFR, I'd rather use UK than USA figures, because the scenarios are for the UK. If you prefer to use lower IFR rates than the shape of the curves will follow the same pattern, just with lower numbers.

Even if the virus was active in the UK earlier than first thought, that doesn't affect my scenarios which apply different levels of R-values to the current daily infection figure of 8,000 given by the government in the most recent daily briefings.

Your points relate to the total eventual UK death toll, which is something I haven't even attempted to address.

Obviously I disagree on a number of factual issues. However, what is key in this situation is that the government should be aware of the numbers of people being admitted to hospital with pneumonia. Hence they should have a good warning of increases in infections (if any) well before people start dying in any numbers.

Personally I expect a smaller second wave in winter. (almost regardless of what the government does)

Yes, completely agree. I simply used a 1st August lockdown date as an illustration. In practice, the government would have a good idea of the new R-value within 2-3 weeks of easing the lockdown, but at that point the number of deaths would still look very low to the general public, so it would be hard for the government to convince people of the need to go back into lockdown, and crucially, obey the lockdown rules.

[Nimrod103]

Obviously I disagree on a number of factual issues. However, what is key in this situation is that the government should be aware of the numbers of people being admitted to hospital with pneumonia. Hence they should have a good warning of increases in infections (if any) well before people start dying in any numbers.

Personally I expect a smaller second wave in winter. (almost regardless of what the government does)

Surely, with 200,000 tests per day, the Govt will have an indication of a second wave long before patients start presenting themselves at hospital with pneumonia.

I am very doubtful there will be a second wave, but most things about this infection so far have been a surprise.

[servodude]

I am very doubtful there will be a second wave

Is that because of the very low levels of new cases currently occurring?
Or because of the apparent stringent observation of social distancing?
Or because of strict border controls?
Or because everyone's had it already?

-sd

[johnhemming]

Surely, with 200,000 tests per day, the Govt will have an indication of a second wave long before patients start presenting themselves at hospital with pneumonia.

That's an interesting question. It depends, of course, upon who the government test. In theory I suppose if the tests are random tests of the population as a whole it may give an indication as to levels of infection in the population as a whole, but I don't think they will test that way. Hence it probably won't give that answer.

[Nimrod103]

I am very doubtful there will be a second wave

Is that because of the very low levels of new cases currently occurring?
Or because of the apparent stringent observation of social distancing?
Or because of strict border controls?
Or because everyone's had it already?

-sd

Mainly ignorant desperate hope on my part. However, it has been widely reported today (https://www.dailymail.co.uk/news/articl ... otent.html) that Italian doctors think the virus is weakening.

Also just a feeling I have from the dynamics of the infection in London, where observance of the rules seems not too good, yet the rate of infection has plunged. I really feel as if a level of immunity has been reached, in some way inexplicable.

[Sorcery]

I am very doubtful there will be a second wave

Is that because of the very low levels of new cases currently occurring?
Or because of the apparent stringent observation of social distancing?
Or because of strict border controls?
Or because everyone's had it already?

-sd

Mainly ignorant desperate hope on my part. However, it has been widely reported today (https://www.dailymail.co.uk/news/articl ... otent.html) that Italian doctors think the virus is weakening.

Also just a feeling I have from the dynamics of the infection in London, where observance of the rules seems not too good, yet the rate of infection has plunged. I really feel as if a level of immunity has been reached, in some way inexplicable.

The Nic Lewis model mentioned way back (but it's not his, it's someone else's, he has replicated an epidemiologist's model), might make it explicable.
Am struggling a little with it because I would want to rewrite the model in my own way to avoid his mistakes (if any) and that will unfortunately create new mistakes (mine). Think the seed of it is, susceptibility correlates with infectiousness. The most susceptible get infected and become the super-spreaders. They either recover or die but once no longer spreading, that leaves a less susceptible and less infectious uninfected population. Hence Herd Immunity Thresh-hold (HIT) occurs at a far lower % than with the classical model where HIT = (1 -1/Ro). The classical model works for vaccinations because it's random who gets them first (in the susceptible - insusceptible range).

Anyway Nic Lewis has another post up, this one tries to work out if and when lockdowns are worth it, here
https://judithcurry.com/2020/05/29/when ... /#comments

[servodude]

I am very doubtful there will be a second wave

Is that because of the very low levels of new cases currently occurring?
Or because of the apparent stringent observation of social distancing?
Or because of strict border controls?
Or because everyone's had it already?

-sd

Mainly ignorant desperate hope on my part. However, it has been widely reported today (https://www.dailymail.co.uk/news/articl ... otent.html) that Italian doctors think the virus is weakening.

Also just a feeling I have from the dynamics of the infection in London, where observance of the rules seems not too good, yet the rate of infection has plunged. I really feel as if a level of immunity has been reached, in some way inexplicable.

Nothing wrong with hope!

I do think that a good proportion of people understand the motives for hygiene in public; which is where I'm hanging most of my hope.

I expect a bit of an uptick in cases as activity starts moving towards normal; hopefully there's enough vigilance around testing of cases to track any change and know that it's manageable (how they might act to remedy any change is more of a tricky issue).

That mail article should be read as if it comes from the daily mail: anything that starts assigning intent to the behaviour of a virus is probably wrong (to put it mildly)
- at least they included some of the detractors in the latter half of the article

There is some good stuff being done globally on tracking the changes in the virus - but you don't do it by counting the amount in a sample 9https://theconversation.com/heres-how-scientists-are-tracking-the-genetic-evolution-of-covid-19-134201)

stay well
- sd

[servodude]

susceptibility correlates with infectiousness.

Indeed.

One's a function of the host - the other of the virus
- both affect the likelihood of catching the virus if exposed

- sd

[servodude]

https://www.theguardian.com/world/2020/jun/01/spate-of-possible-uk-coronavirus-cases-from-2019-come-to-light

A day before the first confirmed fatality from coronavirus outside mainland China was reported on 2 February this year, the death of the influential guitarist and musician Andy Gill was announced. The 64-year-old, who fronted the post-punk band Gang of Four, died of pneumonia after two weeks in St Thomas’ hospital in London.

I listened to Catherine Mayer interviewed recently; apparently they are looking to have samples from Andy tested

I saw him play in November and I think they were heading to China soon afterwards (quite plausible that there was a variant of this around there at that time)
- they were originally meant to play back in March but that had been postponed because Andy had a chest infection

"In this land right now some are insane, and they're in charge"

- sd

[Itsallaguess]

Also just a feeling I have from the dynamics of the infection in London, where observance of the rules seems not too good, yet the rate of infection has plunged. I really feel as if a level of immunity has been reached, in some way inexplicable.

One question that's been rattling around my head a little is why we only ever hear the single phrase 'herd-immunity', where it's generally applied to country-level population numbers, and levels of around the 70% infection rate expected before 'herd-immunity' might be achieved...

Is there any consideration at all to what we might call 'sub-herd immunity', and how that might benefit the larger 'herd' with potentially much lower infection-numbers?

Imagine for a minute that for somewhere like London, where a large initial spike of infections and deaths was seen, there exists large 'sub-herds' who 'generally' have very common 'outside-home' movement routines.

Think of it along the lines of things like this -

• home / tube / work / tube / home

• home / bus / work / bus / home

• home / walk / work / walk / home

Given that generally, and certainly during the working-week, people's activity-times and patterns in relation to the above routines are likely to be fairly regular, and then outside of those routines there will of course be some 'non-routine' activities, but perhaps where very close contact with large numbers of people are at a very much reduced level, then if we might look to 'group' the numbers of people who might regularly carry out similar 'clockwork' routines (times / particular transport / locations) into 'sub-herds', where, once a given level of infection has passed through those 'sub-herds', and perhaps a level of 'sub-herd-immunity' has begun to develop, then might we perhaps then get to a point where 'city-level' herd immunity might actually begin to develop, but where only very small numbers of people actually 'posses' the 'sub-herd-immunity' that delivers it?

As a pointed example of the above, then consider a group of 10,000 people, but where only 1,000 generally ever leave their homes. In that scenario, why would 'herd-immunity' for the 10,000 people require that, for example a given level of 7,000 (70%) need to have had it?

Maybe so long as 700 of the 1,000 who move around have had it, then the external results might begin to look exactly the same in the general population infection figures when compared to a second group of 10,000, where they all move around, and 7,000 (70%) of those have become infected at a much later time...

Just some idle thoughts on the above specific point regarding London, where it's clear that the infection rate has now dropped dramatically and relatively quickly, with little explanation as to how this might happen in such a crowded and busy city..

I'm happy for the above to be poked and hand-grenades used if there's any faulty thinking - it is very early!

Cheers,

Itsallaguess

[johnhemming]

I think it would be reasonable to expect London to be less susceptible to infection now as the primary wave has probably gone through London and lockdown came in too late to have an effect on the peak.

I would still, however, expect some deaths in a second wave later this year in London and the South East.

An interesting question is what happens with the virus over the summer when it is less infectious. That could continue to build up some immunity and it may also result in people getting less of a viral load and hence not responding as badly.

Whichever way I think the UK has had the big first wave and any later waves of infection will be lower.

I am also expecting there to be more pressure to lift lockdown faster as it becomes obvious the impact of the virus is dissipating (for now).

I would think the second wave will be higher outside the South East, but less so in the big cities.

[GoSeigen]

[In London] lockdown came in too late to have an effect on the peak.

I've probably missed some sort of conclusive study, but could you say how we know this with so much confidence?

GS

[servodude]

I'm happy for the above to be poked and hand-grenades used if there's any faulty thinking - it is very early!

No that's all pretty sound
- its droving your herds in groups or keeping them in different fields - they can only catch stuff from the group they're mixed in with
- introduce a new bull though and you can quickly spread novel stuff around (which to be honest is probably why you bought him)

It makes some sense to apply it to populations because it's a big funge and relies on the smoothing of large numbers
- in reality the outbreak(s) are likely to be sporadic and clustered as interlopers infect between their local herds

- sd

[johnhemming]

[In London] lockdown came in too late to have an effect on the peak.

I've probably missed some sort of conclusive study, but could you say how we know this with so much confidence?

GS

The peak date of deaths in England was 8th April.

[GoSeigen]

[In London] lockdown came in too late to have an effect on the peak.

I've probably missed some sort of conclusive study, but could you say how we know this with so much confidence?

GS

The peak date of deaths in England was 8th April.

So...?

How long are we assuming it takes for lockdowns to have an effect and how do we know?

GS
[EDITED: Clicked submit by mistake.]

[johnhemming]

I have posted about this before. The steps are .
a) Someone gets infected
b) They show symptoms
c) If Ill enough they get admitted to hospital
d) They may go into ICU
e) they may get ventilated
f) They die (if ill enough)

The government have access to reliable figures for c, d, e and f.

The evidence is that a-f is at least on median average 23 days. In fact probably longer.

Hence if the peak of deaths in England was on 8th April then you can work backwards to the date of peak infection.

[servodude]

I have posted about this before. The steps are .
a) Someone gets infected
b) They show symptoms
c) If Ill enough they get admitted to hospital
d) They may go into ICU
e) they may get ventilated
f) They die (if ill enough)

The government have access to reliable figures for c, d, e and f.

The evidence is that a-f is at least on median average 23 days. In fact probably longer.

Hence if the peak of deaths in England was on 8th April then you can work backwards to the date of peak infection.

That's a whopping big house of cards.
You said it was too late to have had "an effect on the peak"
- are you claiming that it affected neither the timing nor magnitude?
- that the social distancing brought about by the lockdown directive had no impact?

None?
-sd

[johnhemming]

I think it is obviously the case that it had no effect on the timing. It is quite possible that it may have had a small effect on the magnitude, but one would have to study the details of the individual cases to work out how much of an effect that depends substantially on the spread. I would be surprised if it could have an effect in excess of 25%. I would think the social distancing prior to lockdown did affect the timing and the magnitude and the lockdown itself had an effect on the numbers of deaths following the peak and possibly in this first wave directly from Covid-19.

[zico]

One question that's been rattling around my head a little is why we only ever hear the single phrase 'herd-immunity', where it's generally applied to country-level population numbers, and levels of around the 70% infection rate expected before 'herd-immunity' might be achieved...

Is there any consideration at all to what we might call 'sub-herd immunity', and how that might benefit the larger 'herd' with potentially much lower infection-numbers?

Itsallaguess

Sub-herd immunity seems like pretty sound logic to me, but very difficult to measure.
I've also been scratching my head about London's much sharper decline in cases than any other region. Here's my hypothesis for people to shoot at (unsupported by data).

What's different about London? Public transport (especially tube) probably used far more intensively than any other city in UK. So, lots of packed tubes/trains/buses for fairly long commutes in very close proximity to lots of different people (particularly tubes). If you assume each tube journey is a potential "superspreader" event, then if most people stop using public transport, then the potential for infection falls dramatically.