Nimrod103 wrote:
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