Continuation The One Covid-19 Science and Medicine Thread Part 2

[Myriad]

Originally Posted by The Atheist

And there was me thinking you respected evidence, which is why I posted UNESCO's findings on schools. There are clear negatives to kids not going to school, some of which can be lifelong. It also affects girls far more than boys, but what do facts matter when faced with evidence we don't like?

I think UNSECO would have made a stronger case if they'd stuck to issues that related to the basic intended purpose of schools.

As it is, at least half their bullet points would apply just as well to a proposal to close a minimum-security prison, put the short-timers on probation, and move the hardcore violent offenders to a different prison. "Oh, but the convicts would miss the nutritionally balanced meals the prison provides. And some would miss their training and counseling programs. And once out of prison, they might become crime victims themselves. And the prison staff would have less job security. And hiring more probation officers would cost money. And prisons are hubs of social activity and human interaction that the convicts need for their rehabilitation. Plus, when we want to do psychological studies on convicts, it's so much easier to find them when they're in cells rather than living on their own."

[JeanTate]

Originally Posted by Rolfe

I was going to point out that in common with every other virus known to mankind, herd immunity will only happen with a vaccine. But I see this has turned into a snark-fest so as you were.

That seems to be inconsistent with what’s in the WP entry I linked to earlier*.

Can you expand on this please? Not limited to viruses contagious to humans, but all viruses known to mankind.

There are some interesting HIT (herd immunity threshold) values in the WP article; for COVID-19, it’s 50-83%.

*one mistake I made: the concept applies to infectious viruses

[Rolfe]

Herd immunity is the level of population protection at which the virus can no longer find new hosts and dies out.

Someone has been editing Wikipedia recently to bring it into line with the misuse of the term that has gained traction this year since some politicians redefined it to mean the transition from epidemic flare-ups to endemic disease.

[JeanTate]

Thanks.

Originally Posted by Rolfe

Herd immunity is the level of population protection at which the virus can no longer find new hosts and dies out.

Isn’t that what happened to SARS (in humans)? It died out without the help of a vaccine. Ditto MERS?

While I’m sure robust results are few and far between, doesn’t herd immunity work, in the wild, for viruses contagious to various animals?

Quote:

Someone has been editing Wikipedia recently to bring it into line with the misuse of the term that has gained traction this year since some politicians redefined it to mean the transition from epidemic flare-ups to endemic disease.

What sources would you recommend?

[Skeptic Ginger]

Originally Posted by Rolfe

Herd immunity is the level of population protection at which the virus can no longer find new hosts and dies out.

Someone has been editing Wikipedia recently to bring it into line with the misuse of the term that has gained traction this year since some politicians redefined it to mean the transition from epidemic flare-ups to endemic disease.

I have a pedantic quibble with "dies out." Rather herd immunity means transmission ceases. Small pox died out. Herd immunity to measles takes a very high percentage of the population to be immune to stop transmission. But we have not eliminated it.

The point being we reach herd immunity before the disease is eradicated. It's the point the infection is on the way out.

You are correct though that it doesn't mean the infection becomes endemic. And the term is being misused in political circles in multiple countries.

[Skeptic Ginger]

Originally Posted by JeanTate

Thanks.


Isn’t that what happened to SARS (in humans)? It died out without the help of a vaccine. Ditto MERS?

SARS 1, yes, MERS no.

Originally Posted by JeanTate

While I’m sure robust results are few and far between, doesn’t herd immunity work, in the wild, for viruses contagious to various animals?

It doesn't usually happen. Rather the pathogen is more likely to become endemic in that population, reaching a sort of steady state with flare-ups now and again.


While there was no vaccine for SARS 1, there were no mild cases. Every case was tracked down, contacts isolated until no more transmission occurred.

[marting]

Originally Posted by Rolfe

I was going to point out that in common with every other virus known to mankind, herd immunity will only happen with a vaccine. But I see this has turned into a snark-fest so as you were.

Herd immunity may not be possible absent a vaccine but it can reduce a disease to much lower endemic levels like smallpox was 300 years ago where it tended to be suppressed for a while until a new crop of kids with no immunity got large enough to push R above 1.

But then when Native Americans were exposed to it by European colonialists it was pretty bad.

[Rolfe]

Several different things coming up here. Smallpox didn't die out, it was actively eradicated by a rigorous vaccination campaign. Measles doesn't die out on its own and it takes a very active vaccination policy indeed to get a high enough uptake for herd immunity to kick in. SARS didn't die out on its own, it was aggressively contact-traced into oblivion. MERS is contained but it hasn't died out.

I suppose it's a difficult thing to prove because a virus that infected so many people who then became immune so that it vanished entirely would be a virus we don't know about. But viruses simply don't do this. There's a fundamental contradiction in the middle of it. People do their best not to get infected with a serious disease. They isolate themselves, they hide away. This is the exact opposite from a vaccination campaign where you pull out the maximum percentage of the population that you can to inject them. You can't pull people out of their houses and infect them with a virulent pathogen to protect the community!

You also have a shifting population. New members are being born, without immunity, and you can't line them up at the school break and infect them either - whereas childhood vaccination programmes are structured so as to neutralise the danger of the incoming cohort of naive youngsters and stop them letting the virus back in again and spreading within the population. If this is done right then you don't even need to give the adults booster vaccinations, although you may have to do that if the herd immunity breaks down and the virus gets back in, as has happened with measles from time to time.

Herd immunity is a term that was coined in relation to vaccine science, meaning that the herd (population) as a whole is immune (protected) even though there are individuals within it who are not immune. Because these unprotected individuals are surrounded by immune members of the herd, there's nobody for them to catch the virus from. The virus dies out in the population. This can't happen without a vaccine.

If you had asked the modellers who were bandying around phrases like "a sort of herd immunity" back in March what they meant by that, what they expected to be happening when they got their so-called herd immunity, the answer would not have been that the virus would no longer be present in the population. Graham Medley in an interview in early March was quite clear that his end-point was endemic disease. I think the numbers being talked about were something like 80 deaths a week, forever.

The truly appalling thing about this (OK, the second truly appalling thing, after the death toll that his first aim of having "a good-going epidemic" among the non-vulnerable population would have caused) was that he was happy to unlock the doors of the vulnerable population once this point had been reached, and let them mix freely with everyone else. In a population with endemic SARS-CoV-2. The death toll would have been even more frightful than it actually was.

Originally Posted by Me

Actual herd immunity: enough people vaccinated so the virus gives up and goes away.
Government herd immunity: enough people survived the disease so the virus doesn't cause epidemic spikes any more but just becomes endemic and decreases overall life expectancy by ten years.

https://twitter.com/DrMoragKerr/stat...87223825252356

Many people speak as if the "herd immunity" goal is what Trump described, "one day it will just go away, it will be like a miracle!" Because that's sort of what vaccine-acquired herd immunity does. The virus goes away so that even the vulnerable (the unvaccinated) can mix with society in safety. But that's not what the politicians mean. Their problem is the epidemic surges and spikes. If only these would stop and people would just keep getting ill and dying in manageable numbers, they don't care how long that continues for. (Maybe the idea of chopping a decade or so off of life expectancy is something the bean counters would even welcome.) That's their goal, and they stole the term herd immunity from vaccine science to make it sound more palatable.

You'd have thought that it would be a bit obvious that the best way to protect a population from a deadly disease is not to let most of them catch it, but a lot of people seem to have got carried away by their own cleverness. And most of the journalists, probably not wanting to seem less clever than the so-called experts, didn't call them on it. (There is film of one of them calling out Medley on the death toll implied by the figures he had just airily bandied about, and his squirm was excruciating.)

So no, you can only get "herd immunity" without a vaccine if you redefine herd immunity to mean something quite different from its actual meaning. I'm fairly disturbed that this has become such common currency. However the good news is that once we have a vaccine herd immunity is a real thing and as this virus is significantly less infectious than measles, it should be a moderate pushover to get it eradicated at that point.

There's another point that comes up, and that is population adaptation. I've even heard people speculating that this is what we need and what will end Covid-19!

This takes hundreds of years, if it happens at all. My late senior partner talked about it in relation to myxomatosis in rabbits, and also measles in Native American peoples. It happened quite quickly with the rabbits because they breed like - well, rabbits. Short generation interval. I thought he said it took 30 generations but that's over 600 years in human terms and even in rabbit terms it's too long. But then in April I was listening to a podcast by a historian (who understood this so much better than the bloody scientists) who was discussing it in relation to bubonic plague in European man.

I hadn't realised this, but this is also why plague died out in Europe. After several hundred years of endemic/epidemic behaviour, it wasn't Yersinia pestis that evolved to become less virulent, it was Caucasian Homo sapiens that evolved to become minimally susceptible to the bacterium. This isn't the case with other races and plague is still a problem in the Middle East for example, but apparently European man just doesn't get sick any more. And she (the historian) said "this takes thirteen generations", which is possibly what my colleague said and I misheard him. (She also said that the adaptations to the immune system that defeated plague are also thought to be the reason why western Europeans suffer more from auto-immune disease than other races.)

I'm not convinced this would even happen with SARS-CoV-2, because most of the people it kills have already done their reproducing. So even if Boris Johnson was prepared to wait three or four hundred years for this, he might be disappointed.

[The Atheist]

Originally Posted by JeanTate

What makes SARS-CoV-2 unique among viruses?

It's not unique, it's a coronavirus.

How's that herd immunity going for other coronaviruses that infect humans?

Originally Posted by JeanTate

Strange, I thought you were a Fauci fan. What makes you so (hyperbolically?) certain an effective vaccine is impossible (before ~3.3 million people die)?

Nice strawman you've got there. Nowhere did I say 3.3M Americans will die. If you go back and check, I only used that percentage to give a highest number of child deaths. You really do need to learn the difference between statistical probability and final results.

And I've also posted several pieces of information that show a vaccine is likely to work. You're failing miserably.

Originally Posted by JeanTate

“Under control” != “out” Just ask the Aussies. Or Danes. Or ...

Denmark - Daily new case increase = 0.2%
Australia - Daily new case increase = 1.9% and falling

There are dozens of countries growing at well under 1%.

And you know that.

Nice try with Aussie, though - they've had an outbreak; they're controlling it. How about you check them against USA in a fortnight and see who's winning.

Right now, USA is having daily new case increases of 2.2% and rising.

Originally Posted by JeanTate

“raging uncontrollably”? In which US states is COVID doing that?

Srsly?

Look for yourself - just pick a state and go for your life.

Originally Posted by Skeptic Ginger

Your link isn't open access unless I register and I'm not going to.

So you'll just assume what it says.

No problemo.

Originally Posted by Skeptic Ginger

But let's get back to the science because we know what the political message is, convince people kids are being harmed and must go back to school to save them all from suicides and miserable lives (or whatever risk it is that is supposed to outweigh the COVID 19 risk).

I'm not interested in the politics of it, and you need to realise that I don't have a dog in this fight - my kid's at school full time and community transmission hasn't happened in NZ for 80 days.

You don't think there's a downside to kids not attending school. I disagree and UNESCO agrees with that, pointing out that girls are more likely to be disadvantaged by remaining absent.

You're quite welcome to post evidence to support your case.

Originally Posted by Skeptic Ginger

Palm Beach County’s health director warns of risk of long-term damage

Nope.
She actually said: We don’t know how that is going to manifest a year from now or two years from now

Don't know.

Yes, there's a risk, but it's not a known risk.

I do find it amusing you're so concerned with an unknown, unspecified risk while simultaneously denying a known risk. It all reminds me of Rumsfeld's "unknown unknowns".

Originally Posted by Skeptic Ginger

And as for using only the percentage of deaths to falsely conclude children aren't getting infected:

I think you're letting red mist disrupt your judgement, because that's nothing like what I said. I made a brief risk-assessment of death ans never commented on whether children get infected. (which they clearly do)

Originally Posted by Skeptic Ginger

There are a lot of people drawing unsupported conclusions, not just Trumpers.

And I think there are an equal number of people overstating the harm.

Originally Posted by Myriad

As it is, at least half their bullet points would apply just as well to a proposal to close a minimum-security prison...

I've long said the closest type of institution to schools are prisons, and you're right on all counts.

The big problem is, kids don't go to prison. Well, not in enlightened countries, so you're talking about two completely different demographics, with completely different risks. Not many 70 yos at school, but quite a few in prison.

[The Atheist]

Originally Posted by Rolfe

You'd have thought that it would be a bit obvious that the best way to protect a population from a deadly disease is not to let most of them catch it, but a lot of people seem to have got carried away by their own cleverness.

And what makes that fact worse is that lots of small, vulnerable nations realised early on that it is the best option - stop the disease from infecting people, period.

Works for us and most of the [South] Pacific Islands. Vietnam & SK as well, showing you don't need to be an island.

[JeanTate]

Thanks.

Just one, for now ...

Originally Posted by The Atheist

<snip>
Srsly?

Look for yourself - just pick a state and go for your life.

<snip>

I did.

Could not find any evidence of COVID “raging uncontrollably” in any US state (or territory).

Must be more nonsense hyperbole.

[Puppycow]

Originally Posted by JeanTate

Isn’t that what happened to SARS (in humans)? It died out without the help of a vaccine. Ditto MERS?

Not because of herd immunity, but by tracing and quarantining.

Quote:

While I’m sure robust results are few and far between, doesn’t herd immunity work, in the wild, for viruses contagious to various animals?

Eventually perhaps, but sometimes at great cost. Think about the Black Death in Europe.

[TellyKNeasuss]

An interesting (at least to me) tidbit from a Washington Post article on super-spreaders (bolding mine):

Quote:

Scientists suspect these “super-emitters” may have much higher levels of the virus in their bodies than others, or may release them by talking, shouting or singing in a different way from most people. Research based on the flu, which involved college students blowing into a tube, showed that a small percentage tended to emit smaller particles known as aerosols more than others.

and an interesting claim from the same article:

Quote:

Donald Milton, a professor of environmental health at the University of Maryland, and other experts have wondered if superspreading events could be the “Achilles’ heel” of the virus. If we could pinpoint the conditions under which these clusters occur, Milton argued, we could lower the transmission rate enough to extinguish the spread.

https://www.washingtonpost.com/healt...ge%2Fstory-ans

[The Atheist]

Originally Posted by JeanTate

Could not find any evidence of COVID “raging uncontrollably” in any US state (or territory).

Then you haven't even looked or are being plain dishonest.

What does CDC have to say on the subject?

Quote:

The novel coronavirus is spreading too fast and across too many places in the United States to bring it under control, a top expert said Monday as some states set records for new cases every day.

Let me work this out....

If it's "spreading too fast to bring under control" I'm pretty sure even my stupid bush logic says that means it's out of control now.

https://www.voanews.com/covid-19-pan...dc-expert-says

Originally Posted by Puppycow

Not because of herd immunity, but by tracing and quarantining.

Also, SARS & MERS had the luxury of people only being infectious once they were symptomatic.

Trace & quarantine works, but as many countries have shown, you need to do it from the start.

[marting]

Originally Posted by The Atheist

Also, SARS & MERS had the luxury of people only being infectious once they were symptomatic.

Trace & quarantine works, but as many countries have shown, you need to do it from the start.

The USA Covid-19 situation is highly variable from one state to the other.

Trace and quarantine works but requires these factors:

1. Community spread has to be low enough that it's doable. This is the case in some states, particularly the ones most hard hit in the North East but is a long way from feasible in much of the Southern states.

2. Where community spread is too large for T&Q, NPI, aka shutdowns and masks have to be implemented and observed widely. This hasn't been done effectively in many states where R was reduced only to around 1. Had it been reduced another 20% back then T&Q would have been feasible. But with "opening up" lots of people were grouping together in bars, delayed wedding, etc. with a huge increase in infections. So now we are doing shutdowns part deux. I'm not optimistic as there is a lot of resistance. OTOH, masks finally seem to be more widely used. So we'll see. It'll be another few weeks to see what effect recent changes have made in Calif. where I'm at. Probably not too different in TX, AZ, and FL though they have a higher percentage of people that think Covid-19's is fake news. All of us southern states had about 1/10th the problem NY, MA, NJ, etc. had so it's just starting to become real to many here.

3. Eventually, either in the next few weeks, or months from now after a lot more infections people will eventually come around. Also, as a higher percentage of people have gotten Covid the R value for will naturally reduce. An R of 1.1 will become .9 for instance. So it will be an interplay between behavior and percent previously infected. What we don't know is what percentage of the population has to get infected to drive R below 1 when a population is partially adhering to NPI requests. Probably somewhere between 15% and 50% depending on the state. But eventually community spread should decline to the point T&Q can be effective assuming we follow the trajectory of most European states. The only question is how many people have to die to get there.

And all this also assumes some degree of immunity from prior infection which is a big unknown as is whether a vaccine is even possible. But this will be known at some point.

There is one bit of good news in all the bad in the USA.

The new infections are heavily skewed towards people below the age of 60 so the deaths associated will be much lower than that in the North East where the distribution of Covid-19 cases was fairly evenly spread amongst age groups. BTW, this is also what's happening in Sweden where cases are still high but deaths have been on a long decline. They had a shift starting 3 months ago where older people were far less likely to get Covid-19. A very similar thing is now happening in Southern states though delayed in comparison to Sweden. Whether it continues remains to be seen but it's a good bet older people are much more aware how at risk they are than was the case not long ago.

[Skeptic Ginger]

Ignoring the poppycock like claiming we don't know what will happen isn't a warning or that somehow living in a COVID free zone makes one neutral:


Texas Tribune July 1st: More than 300 children in Texas day cares have caught COVID-19, and the numbers are rising

TX Tribune July 5th: Texas parents face a frightening lack of information on coronavirus risks in child care centers

Quote:

According to the state health agency, as of Wednesday, Texas children and staff reported 1,695 positive cases at 1,078 child care centers, about 8.8% of the centers open as of this week. About a third of the cases were children, and the rest were staff.

In mid-May, 59 confirmed cases among children and staff had been reported. By the end of June the total had risen to 950, including 307 children and 643 staff.

TX Tribune today: 85 babies under 1 year old in Nueces County have tested positive for COVID-19, according to report

And some claim it's safe to open schools?

[Orphia Nay]

That's on 17 July.

Google's latest is from 16 July. 936 deaths; 142K cases.

Going down? Myriad?

I also saw on Fox News (know thine enemy) 2 days ago that the Florida health department records haven't been up to reporting cases and recovered cases, so their stats were highly inflated by a factor of 10.

[Pixel42]

It's the global trends that are worrying me.

[Planigale]

Originally Posted by Rolfe

Several different things coming up here. Smallpox didn't die out, it was actively eradicated by a rigorous vaccination campaign. Measles doesn't die out on its own and it takes a very active vaccination policy indeed to get a high enough uptake for herd immunity to kick in. SARS didn't die out on its own, it was aggressively contact-traced into oblivion. MERS is contained but it hasn't died out.

I suppose it's a difficult thing to prove because a virus that infected so many people who then became immune so that it vanished entirely would be a virus we don't know about. But viruses simply don't do this. There's a fundamental contradiction in the middle of it. People do their best not to get infected with a serious disease. They isolate themselves, they hide away. This is the exact opposite from a vaccination campaign where you pull out the maximum percentage of the population that you can to inject them. You can't pull people out of their houses and infect them with a virulent pathogen to protect the community!

You also have a shifting population. New members are being born, without immunity, and you can't line them up at the school break and infect them either - whereas childhood vaccination programmes are structured so as to neutralise the danger of the incoming cohort of naive youngsters and stop them letting the virus back in again and spreading within the population. If this is done right then you don't even need to give the adults booster vaccinations, although you may have to do that if the herd immunity breaks down and the virus gets back in, as has happened with measles from time to time.

Herd immunity is a term that was coined in relation to vaccine science, meaning that the herd (population) as a whole is immune (protected) even though there are individuals within it who are not immune. Because these unprotected individuals are surrounded by immune members of the herd, there's nobody for them to catch the virus from. The virus dies out in the population. This can't happen without a vaccine.

If you had asked the modellers who were bandying around phrases like "a sort of herd immunity" back in March what they meant by that, what they expected to be happening when they got their so-called herd immunity, the answer would not have been that the virus would no longer be present in the population. Graham Medley in an interview in early March was quite clear that his end-point was endemic disease. I think the numbers being talked about were something like 80 deaths a week, forever.

The truly appalling thing about this (OK, the second truly appalling thing, after the death toll that his first aim of having "a good-going epidemic" among the non-vulnerable population would have caused) was that he was happy to unlock the doors of the vulnerable population once this point had been reached, and let them mix freely with everyone else. In a population with endemic SARS-CoV-2. The death toll would have been even more frightful than it actually was.




https://twitter.com/DrMoragKerr/stat...87223825252356

Many people speak as if the "herd immunity" goal is what Trump described, "one day it will just go away, it will be like a miracle!" Because that's sort of what vaccine-acquired herd immunity does. The virus goes away so that even the vulnerable (the unvaccinated) can mix with society in safety. But that's not what the politicians mean. Their problem is the epidemic surges and spikes. If only these would stop and people would just keep getting ill and dying in manageable numbers, they don't care how long that continues for. (Maybe the idea of chopping a decade or so off of life expectancy is something the bean counters would even welcome.) That's their goal, and they stole the term herd immunity from vaccine science to make it sound more palatable.

You'd have thought that it would be a bit obvious that the best way to protect a population from a deadly disease is not to let most of them catch it, but a lot of people seem to have got carried away by their own cleverness. And most of the journalists, probably not wanting to seem less clever than the so-called experts, didn't call them on it. (There is film of one of them calling out Medley on the death toll implied by the figures he had just airily bandied about, and his squirm was excruciating.)

So no, you can only get "herd immunity" without a vaccine if you redefine herd immunity to mean something quite different from its actual meaning. I'm fairly disturbed that this has become such common currency. However the good news is that once we have a vaccine herd immunity is a real thing and as this virus is significantly less infectious than measles, it should be a moderate pushover to get it eradicated at that point.

There's another point that comes up, and that is population adaptation. I've even heard people speculating that this is what we need and what will end Covid-19!

This takes hundreds of years, if it happens at all. My late senior partner talked about it in relation to myxomatosis in rabbits, and also measles in Native American peoples. It happened quite quickly with the rabbits because they breed like - well, rabbits. Short generation interval. I thought he said it took 30 generations but that's over 600 years in human terms and even in rabbit terms it's too long. But then in April I was listening to a podcast by a historian (who understood this so much better than the bloody scientists) who was discussing it in relation to bubonic plague in European man.

I hadn't realised this, but this is also why plague died out in Europe. After several hundred years of endemic/epidemic behaviour, it wasn't Yersinia pestis that evolved to become less virulent, it was Caucasian Homo sapiens that evolved to become minimally susceptible to the bacterium. This isn't the case with other races and plague is still a problem in the Middle East for example, but apparently European man just doesn't get sick any more. And she (the historian) said "this takes thirteen generations", which is possibly what my colleague said and I misheard him. (She also said that the adaptations to the immune system that defeated plague are also thought to be the reason why western Europeans suffer more from auto-immune disease than other races.)

I'm not convinced this would even happen with SARS-CoV-2, because most of the people it kills have already done their reproducing. So even if Boris Johnson was prepared to wait three or four hundred years for this, he might be disappointed.

The highlighted is nonsense and verging on race science. A historian is a poor source for an expert opinion on innate immunity to infections and sad that you should rate a poorly remembered broadcast from a historian as better evidence than research from scientists. 'The European race' whatever that is do not have innate immunity to plague, plague ceased to be an issue due to sanitary regulations. Whilst individual auto-immune conditions vary in their epidemiology, many are more common in those of African or Asian ethnicity. There may be a relationship to immunological priming and early childhood infections (for which poverty and ethnicity may be surrogates), there may be an issue around access to diagnosis (as above for issues around access).

Better examples of acquired immunity would be to malaria and haemoglobin gene polymorphisms such as haemoglobin S or C or thalassaemia. There is evidence that SLE an autoimmune condition may be associated with genetic resistance to trypanosomiasis explaining the higher incidence of SLE in those from endemic areas.

An example of herd immunity naturally occurring would be the 1918 flu epidemic. The original strain disappeared, flu recirculates because it changes its antigenicity, but the previous strains effectively disappear because of herd immunity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4660050/
https://www.nature.com/articles/s41435-019-0065-0

[rjh01]

Originally Posted by Planigale

The highlighted is nonsense and verging on race science. A historian is a poor source for an expert opinion on innate immunity to infections and sad that you should rate a poorly remembered broadcast from a historian as better evidence than research from scientists. 'The European race' whatever that is do not have innate immunity to plague, plague ceased to be an issue due to sanitary regulations. Whilst individual auto-immune conditions vary in their epidemiology, many are more common in those of African or Asian ethnicity. There may be a relationship to immunological priming and early childhood infections (for which poverty and ethnicity may be surrogates), there may be an issue around access to diagnosis (as above for issues around access).

Better examples of acquired immunity would be to malaria and haemoglobin gene polymorphisms such as haemoglobin S or C or thalassaemia. There is evidence that SLE an autoimmune condition may be associated with genetic resistance to trypanosomiasis explaining the higher incidence of SLE in those from endemic areas.

An example of herd immunity naturally occurring would be the 1918 flu epidemic. The original strain disappeared, flu recirculates because it changes its antigenicity, but the previous strains effectively disappear because of herd immunity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4660050/
https://www.nature.com/articles/s41435-019-0065-0

What you highlighted in your quote is reasonable. For many centuries many Europeans lived in dirty cities. The survivors of these times would have had a very good immune system. They then went to the American continent where they bought smallpox. This devastated the natives who had never been hit by such diseases. 80-90% of the natives were killed by it. Yet it killed only 30% or so of the Europeans.

Ref: https://en.wikipedia.org/wiki/Smallpox

[Planigale]

Originally Posted by Skeptic Ginger

Ignoring the poppycock like claiming we don't know what will happen isn't a warning or that somehow living in a COVID free zone makes one neutral:


Texas Tribune July 1st: More than 300 children in Texas day cares have caught COVID-19, and the numbers are rising

TX Tribune July 5th: Texas parents face a frightening lack of information on coronavirus risks in child care centers

TX Tribune today: 85 babies under 1 year old in Nueces County have tested positive for COVID-19, according to report

And some claim it's safe to open schools?

I think the problem is what do we mean by safe. The risk to children from covid-19 is small but not zero. It is certainly below the risks we accept for other issues. So for the children it is probably safe. Unlike flu children are not the major spreaders of infection. Children can spread infection, but R is probably below 1. So the question is how much of a risk - how unsafe are school openings for teachers and families. In general the parents of children are younger adults, the significant risk relates to the grandparents. (In the UK figures show that risk of dying doubles for every seven years of age.)

Can we be more specific with our schools and children's education? Ensure that children with at risk families are segregated? Should they board? Ensure parents do not socialise at drop off pick up time is probably important.

[Planigale]

Originally Posted by rjh01

What you highlighted in your quote is reasonable. For many centuries many Europeans lived in dirty cities. The survivors of these times would have had a very good immune system. They then went to the American continent where they bought smallpox. This devastated the natives who had never been hit by such diseases. 80-90% of the natives were killed by it. Yet it killed only 30% or so of the Europeans.

Ref: https://en.wikipedia.org/wiki/Smallpox

The problem is the assumption that Smallpox is one disease, in fact variant strains existed with differing mortality but causing cross resistance. Less virulent strains were common in Europe so simple comparisons of mortality may not be comparing like with like. In addition as an endemic illness smallpox tended to infect children, those who survived would be immune. Therefore the adult colonists would be immune, the susceptible population would tend to be the children, and small pox was less disruptive socially and the parents could care for their children with little risk. In contrast native American populations were entirely susceptible, so with the loss of the adult population to illness there would have been no food preparation etc. There is no need to create some special immune virtue in the European and an innate weakness of the Native to explain differential mortality.

Interestingly the trigger for the development of Smallpox may have been the arrival of camels in Africa (remembering camels originated in South America and took some millions of years to get to Africa). Rather like MERS camels may then have acquired an ancestral form of smallpox that domesticated camels spread to humans that then evolved into Smallpox a few thousand years ago. In the meantime the ancestors of the indigenous population of the Americas had migrated in the opposite direction to the camels, and had become isolated in the Americas before Smallpox appeared in Africa and subsequently spread throughout the old world. Another trigger for Smallpox may have been a climate change event (volcanic eruption) causing movements in fauna, leading to a rodent virus infecting camels. Climate change may lead to an increased frequency of pandemic events.

[Rolfe]

Originally Posted by Puppycow

Not because of herd immunity, but by tracing and quarantining.

Yes.

Originally Posted by Puppycow

Eventually perhaps, but sometimes at great cost. Think about the Black Death in Europe.

No. It doesn't happen. Not ever. I can't stress this enough.

As I said in an earlier post, the Black Death (Yersinia pestis) ran rampant for quite some time in epidemic waves then settled down to a more endemic pattern although still with some epidemic surges within that pattern. It didn't go away because it made too many people immune, it went away because eventualy the host organism evolved. People who had the right genetics for the situation were naturally selected to survive and eventually all the survivors had these genes. Not immunity, evolution.

I'm pretty sure we don't want to wait until we've evolved resistance to SARS-CoV-2. Particularly since I suspect it wouldn't happen anyway. The mortality rate isn't high enough and the people who die have mainly already reproduced as much as they're going to.

ETA: I see a later post disputing this. It's a derail I'm not getting into, but this phenomenon definitely exists. It's not "race science" in a pejorative way to note that different races have some different physical characteristics. Tolerance to lactose is another one. Ethnic origin is a definite factor in disease susceptibility from sickle cell anaemia to cystic fibrosis. And the broadcast isn't poorly remebered, it's still there on YouTube. She merely brought together some things I was already familiar with.

[Delphic Oracle]

The existence of genetic abnormalities does not support your ideas of varying viral susceptibility.

Genetic abnormalities are not contagious, first of all...

[anduin]

Delurking to post. I have a very personal interest in this fight, I caught Covid-19 during a trip to Paris in early March, before the lock-down. I developed symptoms on Saturday March 14, just a small fever and a cough at first, then the symptoms got worse. Cough, tight chest, fever, eventually diarrhoea and lost my sense of small, but things got better after 3 weeks, but I still felt a bit off.

Then the symptoms continued, and continued, and continued.

I'm still sick, I'm one of the Long Covid contingent, tens of thousands of us are congregating online sharing our symptoms, most have been sick for 4 months.

I no longer have covid, I had a negative test 2 weeks ago, but I have a range of symptoms, chest pain, coughing, shortness of breath, brain fog, fatigue, if I over-do physical activity I become extremely fatigued and can't get out of bed.

I've had blood test, everything seems fine, and an inconclusive X-ray, so if things continue as they are I will get a lung scan, I can feel there's something wrong with my lungs. This disease is the worst thing that has happened to me, and for at least 10% of patients it seems to linger is some sort of post-viral infection.

[Skeptic Ginger]

Originally Posted by Rolfe

...

As I said in an earlier post, the Black Death (Yersinia pestis) ran rampant for quite some time in epidemic waves then settled down to a more endemic pattern although still with some epidemic surges within that pattern. It didn't go away because it made too many people immune, it went away because eventualy the host organism evolved. People who had the right genetics for the situation were naturally selected to survive and eventually all the survivors had these genes. Not immunity, evolution. ...

If you are talking about the CCR5 deletion, that's only in a small percent of the European population. And it may have had only a limited effect on the plague. It may be that plague amplified that mutation but not by that much.

Plague subsided with decreased exposure, and later with antibiotics.

Nature: CCR5 mutation and plague protection

Quote:

Here we infect both normal and CCR5-deficient mice with the bacterium Yersinia pestis, the cause of the plague epidemics that wiped out one-third of Europeans in the Middle Ages3, and find no difference in either bacterial growth or survival time between the two groups. Unless the pathogenesis of Yersinia infection differs markedly between mice and humans, our results indicate that CCR5 deficiency in people is unlikely to protect against plague.

Wiki

Quote:

A study measuring allele frequencies in 18 European populations found a North-to-South gradient, with the highest allele frequencies in Finnish and Mordvinian populations (16%), and the lowest in Sardinia (4%).[46]

[Skeptic Ginger]

Originally Posted by Delphic Oracle

The existence of genetic abnormalities does not support your ideas of varying viral susceptibility.

Genetic abnormalities are not contagious, first of all...

Pathogens can exert a selective pressure on human genetics (and all animals) that after many generations can result in a genetic amplification of certain genetic mutations. It takes thousands of years.

[Skeptic Ginger]

Originally Posted by Planigale

I think the problem is what do we mean by safe. The risk to children from covid-19 is small but not zero. It is certainly below the risks we accept for other issues. So for the children it is probably safe. Unlike flu children are not the major spreaders of infection. Children can spread infection, but R is probably below 1. So the question is how much of a risk - how unsafe are school openings for teachers and families. In general the parents of children are younger adults, the significant risk relates to the grandparents. (In the UK figures show that risk of dying doubles for every seven years of age.)

Can we be more specific with our schools and children's education? Ensure that children with at risk families are segregated? Should they board? Ensure parents do not socialise at drop off pick up time is probably important.

Those things are very important.

We know from pathogens like influenza that schools are a common source of propagating the infection.

Conclusions were drawn early on in this pandemic that kids weren't a large source of the infection. That was based on the assumption now shown to be false, that kids aren't catching it.

You can't look at the kids in isolation as if they aren't a source of spread. We don't know.

We've already learned that it was a false assumption only people with symptoms spread the infection.

In Sweden, if I'm getting the data right, teachers didn't have a high rate of infection. There are a half dozen variables I can think of off the top of my head that weren't looked at with the data that was collected on teachers.

[Skeptic Ginger]

Originally Posted by rjh01

What you highlighted in your quote is reasonable. For many centuries many Europeans lived in dirty cities. The survivors of these times would have had a very good immune system. They then went to the American continent where they bought smallpox. This devastated the natives who had never been hit by such diseases. 80-90% of the natives were killed by it. Yet it killed only 30% or so of the Europeans.

Ref: https://en.wikipedia.org/wiki/Smallpox

Living in a dirty city doesn't leave people with a "good immune system".

[Puppycow]

Originally Posted by The Atheist

Also, SARS & MERS had the luxury of people only being infectious once they were symptomatic.

Trace & quarantine works, but as many countries have shown, you need to do it from the start.

It's a bit like a fire. If you spot it early enough you may be able to extinguish it before it grows. But if it spreads too much the whole building is going to burn. It feeds on itself until it runs out of fuel.

[Puppycow]

Originally Posted by anduin

Delurking to post. I have a very personal interest in this fight, I caught Covid-19 during a trip to Paris in early March, before the lock-down. I developed symptoms on Saturday March 14, just a small fever and a cough at first, then the symptoms got worse. Cough, tight chest, fever, eventually diarrhoea and lost my sense of small, but things got better after 3 weeks, but I still felt a bit off.

Then the symptoms continued, and continued, and continued.

I'm still sick, I'm one of the Long Covid contingent, tens of thousands of us are congregating online sharing our symptoms, most have been sick for 4 months.

I no longer have covid, I had a negative test 2 weeks ago, but I have a range of symptoms, chest pain, coughing, shortness of breath, brain fog, fatigue, if I over-do physical activity I become extremely fatigued and can't get out of bed.

I've had blood test, everything seems fine, and an inconclusive X-ray, so if things continue as they are I will get a lung scan, I can feel there's something wrong with my lungs. This disease is the worst thing that has happened to me, and for at least 10% of patients it seems to linger is some sort of post-viral infection.

Thanks for this information. I have read stories like this. May I ask how old you are and how physically fit you were prior to this?

[anduin]

Originally Posted by Puppycow

Thanks for this information. I have read stories like this. May I ask how old you are and how physically fit you were prior to this?

50, quite fit and active, never had any health problems, my only visit to the doctor in the last 10 years was due to a broken rib (fell down the stairs in a stupidly comical home accident). I hike a lot, walk to work, and I have an exercise bike at home which I use 3 times a week.

Now I can barely go out, today I've been in bed most of the day after a long walk yesterday.

I'm in FB groups with younger people, interestingly lots of young women. perhaps that's the demographic that shares their symptoms online.

[JeanTate]

Originally Posted by anduin

50, quite fit and active, never had any health problems, my only visit to the doctor in the last 10 years was due to a broken rib (fell down the stairs in a stupidly comical home accident). I hike a lot, walk to work, and I have an exercise bike at home which I use 3 times a week.

Now I can barely go out, today I've been in bed most of the day after a long walk yesterday.

I'm in FB groups with younger people, interestingly lots of young women. perhaps that's the demographic that shares their symptoms online.

Glad you have de-lurked and joined the discussion here.

May I ask, in the fora where you discuss Long Covid, is there mention of school-age kids with similar, drawn out, challenging symptoms (say, age 4 to 18)?

Also, exercise - often necessarily mild - is (AFAIK) recommended as a possible means of lessening, or alleviating, or making more tolerable fatigue (which, as I’m sure you know all too well, is not the same as tiredness); for people undergoing chemotherapy, for example. Have you found that gentle exercise is helpful? Related: in your discussion group, there are likely people who have had other medical conditions where fatigue is a common symptom (or side effect of treatment). How do they compare the Long Covid fatigue with their other experiences?

[Delphic Oracle]

Originally Posted by Skeptic Ginger

Pathogens can exert a selective pressure on human genetics (and all animals) that after many generations can result in a genetic amplification of certain genetic mutations. It takes thousands of years.

And therefore is completely irrelevant to the discussion taking place.

[anduin]

Originally Posted by JeanTate

Glad you have de-lurked and joined the discussion here.

May I ask, in the fora where you discuss Long Covid, is there mention of school-age kids with similar, drawn out, challenging symptoms (say, age 4 to 18)?

I've read a few people posting about their kids, a few of them with similar long covid, but these seem extremely rare.

The picture that is emerging is that if this doesn't kill you, there's a 10% chance that you end up with lasting organ damage. Liver, kidneys, heart, lungs. Ages of those in the forums are from 20-55. My liver, kidneys and heart appear to be fine, but I fear for my lungs.

Covid-19 could be more like polio.

[JeanTate]

Rolfe: “Herd immunity is the level of population protection at which the virus can no longer find new hosts and dies out.”

Puppycow (re controlling the original SARS): “Not because of herd immunity, but by tracing and quarantining.“

I’m confused; wouldn’t “tracing and quarantining” be a means to attain herd immunity? (leave aside the slight anthropomorphism of a virus “finding” something).

Likewise, wouldn’t some vaccines (not all) also be a means to attain herd immunity?

[anduin]

Originally Posted by JeanTate

Also, exercise - often necessarily mild - is (AFAIK) recommended as a possible means of lessening, or alleviating, or making more tolerable fatigue (which, as I’m sure you know all too well, is not the same as tiredness); for people undergoing chemotherapy, for example. Have you found that gentle exercise is helpful? Related: in your discussion group, there are likely people who have had other medical conditions where fatigue is a common symptom (or side effect of treatment). How do they compare the Long Covid fatigue with their other experiences?

I have found that I can operate at home quite well, carry bags, clean the house, etc. The problem comes if I try to do more, like taking longer walks. A walk to the shops is fine if I don't carry much, but anything longer and I suffer the next day, not just tiredness, fatigue.

Fatigue is the most common symptoms in the group, followed by coughing, constant headaches, palpitations and irregular heart rate, gastrointestinal (diarrhoea, nausea, vomiting, loss of appetite), and a whole range of weird symptoms related to nerves and neurological inflammation. My other main symptom has been loss of balance and my eyesight in one eye.

As for previous fatigue, most of the people posting are healthy and have no experience with any illness, so there's little scope for comparison. A few have had previous illness, and this is nothing like anything they've ever experienced.

[JeanTate]

Thanks.

Originally Posted by anduin

I've read a few people posting about their kids, a few of them with similar long covid, but these seem extremely rare.

Could that be because (very) few kids got “bad covid”?

Quote:

The picture that is emerging is that if this doesn't kill you, there's a 10% chance that you end up with lasting organ damage. Liver, kidneys, heart, lungs. Ages of those in the forums are from 20-55. My liver, kidneys and heart appear to be fine, but I fear for my lungs.

Covid-19 could be more like polio.

So everyone who has long covid had “bad covid” first? As in hospitalization, time in an ICU, on a vent, that sort of thing.

So you have dyspnea (shortness of breath)?

[JeanTate]

Thanks.

Originally Posted by anduin

I have found that I can operate at home quite well, carry bags, clean the house, etc. The problem comes if I try to do more, like taking longer walks. A walk to the shops is fine if I don't carry much, but anything longer and I suffer the next day, not just tiredness, fatigue.

Fatigue is the most common symptoms in the group, followed by coughing, constant headaches, palpitations and irregular heart rate, gastrointestinal (diarrhoea, nausea, vomiting, loss of appetite), and a whole range of weird symptoms related to nerves and neurological inflammation. My other main symptom has been loss of balance and my eyesight in one eye.

As for previous fatigue, most of the people posting are healthy and have no experience with any illness, so there's little scope for comparison. A few have had previous illness, and this is nothing like anything they've ever experienced.

I hang out in some cancer support fora. Common advice from cancer survivors is that the fatigue is a new normal, irrespective of pre-diagnosis/treatment fitness (though many whose cancers went away were able to return to prior levels of fitness, albeit only after several years in some cases). However, within the new normal, exercise seems to be able to help deal with fatigue ... with an almost universal rider: you have to work at it, it’ll take time (and lots of trial and error) to find what works for you, support and encouragement is good (and the internet is replete with scammers, BS cures, etc).

Oh, and as that list of symptoms has a large overlap with those with cancer (treatment), and as many of your fellow long covid sufferers will have close family or friends with cancer, some of you may find discussions with cancer survivors helpful.

[anduin]

Originally Posted by JeanTate

Could that be because (very) few kids got “bad covid”?

Not sure, it could just be under-reporting, nobody in their teens would be using Facebook

Funnily enough I just read about a mother posting on behalf of her 16 year old daughter who is quite poorly.

Originally Posted by JeanTate

So everyone who has long covid had “bad covid” first? As in hospitalization, time in an ICU, on a vent, that sort of thing.

Not at all, if anything it seems more common with people who had very mild initial symptoms, practically nobody was in the ICU, there may be some, but the common denominator in all of us is that we had very mild initial illness.

Strangely enough, my brother was also sick and was in the ICU for a week (oxygen, no ventilator), and he's fully recovered, no fatigue at all, he's out running and swimming.

Originally Posted by JeanTate

So you have dyspnea (shortness of breath)?

Not any more, the last bad episode was weeks ago. Now I have fatigue, bad eyesight, a burning pain in my lungs after exercise, and hoarse voice.