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A inconvenient [immunological] truth

Posted: Fri Mar 13, 2020 2:23 pm
by _Chap
Listening to the BBC today, I heard an immunologist make a clear statement about what governments are really trying to do with COVID-19 - and which, in fact, they currently have no alternative to doing. But they can't say it openly, because it does not sound at all good. I was already aware of the science behind this, but I had not yet seen it so clearly put together and stated so starkly. Here it is:

Governments know that it is not only inevitable that a large part of their populations will be infected with and suffer illness from COVID-19 - they actually need this to happen, because (in the absence of any vaccine), it is the only way to eliminate the virus from their population.

It works like this. Viruses can only live, multiply, and pass through the population if they find suitable human bodies to inhabit for a while (outside human bodies, they die quite quickly). Now, on the whole, a human body that has suffered an infection and recovered from it will have done so by creating antibodies specific to the virus, which will make that body highly inhospitable to future virus visitors of that type. That body then 'has immunity' to the virus in question.

But that's OK, so long as the virus can jump to another previously uninfected (and hence vulnerable by its lack of antibodies) human body, and live and multiply there for a while before infecting another previously uninfected body when the last one has itself developed antibodies and become inhospitable, i.e. immune.

When a virus is new to a population, life is easy. it can find lots of fresh bodies to jump into. But when a substantial proportion of the population have contracted the virus, become ill, then recovered, hence possessing immunity, then when the poor little virus is kicked out of one body it can find nowhere else to go ... and it dies. :cry: Poor little virus!

So, when a large proportion of the population (it does not have to be 100%) has contracted the virus, become ill, recovered, and hence become immune ... the virus actually dies out through lack of suitable hosts. That's called 'herd immunity'. That's what the US population, and every other population, needs to do. It's the only way to make the virus go away.

The trick, however, is to slow down the rate at which the population is infected to the point where the number of sick people needing intensive care is always within the capacity of the available hospital beds. That's hard to do ...

Of course, the US government, or any other government, can't tell people 'Hey! In order to beat this virus we need a lot of you to get sick! Do your duty as good citizens'. True as it is, people don't want to hear that, even if it would be the honest thing to say. And of course the fact that it is the honest thing to say makes it extremely unlikely that Trump will ever say it.


FOOTNOTES:

What about vaccines?
Vaccines are a clever immunological trick to make your body produce antibodies without you having to catch the virus and get sick. But they are irrelevant to COVID-19, since it is highly unlikely that a vaccine for that virus can be developed in less than a year from now.

What about locking down cities, and stuff?
That's basically a tactic, first tried in China, to make the mass infection - herd immunity - virus die-out cycle happen in one limited population segment, so it does not have to happen elsewhere. It's not very likely to work in the US by the look of things.

So (hopefully slow) mass infection is the only way through this. But that is not a nice thing to have to tell people, is it?

Re: A inconvenient [immunological] truth

Posted: Fri Mar 13, 2020 3:26 pm
by _Res Ipsa
That’s what a pure mitigation strategy is. Governments take the resources used in containment, assume that most people will get the virus, and shift all resources to raise the ability of the healthcare system to avoid being overwhelmed at the peak. It’s just like seasonal flu. We don’t demand widespread testing for people with mild flu systems. We do surveillance testing so doctors and hospitals can know what’s coming.

Looking at my county’s numbers, we have over 80 new cases a day. Only eight are under investigation. The others are simply categorized as community spread. Containment and mitigation can be used together, but only if one has the resources.

I’m skeptical that the strategy in Wuhan was mitigation. I suspect it was containment. Having herd immunity in Wuhan doesn’t help the rest of China.

ETA: I don’t think it’s that the government “needs” this to happen. It’s that, if the disease can’t be contained and transmission interrupted, it will happen. It’s not like the government has a choice.

Re: A inconvenient [immunological] truth

Posted: Fri Mar 13, 2020 4:39 pm
by _EAllusion
I think the hope is we can limit population spread to reduce stress on hospital systems until we have meaningful treatments or vaccines in place. If those measures do their job, not enough people will be infected to generate true herd immunity. That’s why people who think we have a couple of months before things go back to business as usual seem very optimistic.

Re: A inconvenient [immunological] truth

Posted: Fri Mar 13, 2020 4:50 pm
by _Res Ipsa
EAllusion wrote:I think the hope is we can limit population spread to reduce stress on hospital systems until we have meaningful treatments or vaccines in place. If those measures do their job, not enough people will be infected to generate true herd immunity. That’s why people who think we have a couple of months before things go back to business as usual seem very optimistic.


Yep. I have my doubts that we will develop herd immunity before there is a vaccine. But, as soon as we get a reliable serology test and more data about immunity and transmission, people who have had the disease can start getting the economy running again.

Re: A inconvenient [immunological] truth

Posted: Fri Mar 13, 2020 11:45 pm
by _Gunnar
Chap wrote:Governments know that it is not only inevitable that a large part of their populations will be infected with and suffer illness from COVID-19 - they actually need this to happen, because (in the absence of any vaccine), it is the only way to eliminate the virus from their population.

So, when a large proportion of the population (it does not have to be 100%) has contracted the virus, become ill, recovered, and hence become immune ... the virus actually dies out through lack of suitable hosts. That's called 'herd immunity'. That's what the US population, and every other population, needs to do. It's the only way to make the virus go away.

The trick, however, is to slow down the rate at which the population is infected to the point where the number of sick people needing intensive care is always within the capacity of the available hospital beds. That's hard to do ...

Of course, the US government, or any other government, can't tell people 'Hey! In order to beat this virus we need a lot of you to get sick! Do your duty as good citizens'. True as it is, people don't want to hear that, even if it would be the honest thing to say. And of course the fact that it is the honest thing to say makes it extremely unlikely that Trump will ever say it.

Yes. I have been thinking a lot about that inevitability ever since the news of the corona virus first broke. Evolution at work! Vulnerable and suitable hosts either die off or become immune after recovery.

The same thing is true of Ebola virus, of course, but because it is so deadly and kills so quickly, it more quickly runs out of new, vulnerable hosts to infect in any given, local breakout.

Re: A inconvenient [immunological] truth

Posted: Sat Mar 14, 2020 7:21 am
by _MeDotOrg
'Herd immunity'. It's funny, but even if mankind does NOT think 'We are one', the virus sure as hell does.

Re: A inconvenient [immunological] truth

Posted: Sat Mar 14, 2020 10:44 am
by _moksha
Hopefully, a COVID-19 vaccine can be developed to eventually give to the most vulnerable part of the population that does not contract the virus at this time. Since this virus is new, nobody has immunity to it except those few who have recovered.

Re: A inconvenient [immunological] truth

Posted: Sat Mar 14, 2020 11:09 am
by _Chap
moksha wrote:Hopefully, a COVID-19 vaccine can be developed to eventually give to the most vulnerable part of the population that does not contract the virus at this time. Since this virus is new, nobody has immunity to it except those few who have recovered.


Yup. But getting a vaccine from start to something that can be used for mass immunisation will take at least a year, according to expert consensus.

While awaiting vaccine development you can either:

(a) Allow a rapid spread amongst the population, with consequent rapid development of large-scale illness-generated immunity which will decrease virus incidence, but with the risk of health facilities being overwhelmed, leading to a high number of deaths, or

(B) You can do your best to slow the spread and depress the death rate by identifying and isolating infected people, and getting people to make burdensome lifestyle changes that will have major economic costs, which will of course also slow the development of large-scale illness-generated immunity.

Re: A inconvenient [immunological] truth

Posted: Sat Mar 14, 2020 1:57 pm
by _Philo Sofee
Mother Nature washing her hands, the virus is her soap.......

Re: A inconvenient [immunological] truth

Posted: Sat Mar 14, 2020 4:22 pm
by _subgenius
Philo Sofee wrote:Mother Nature washing her hands, the virus is her soap.......

huh?

Did you just rationalize Jeffrey Dahmer as an attribute of natural selection?

Yep, you sure did.