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Old 05-14-2020, 03:46 PM
Fotheringay-Phipps is offline
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Are some people inherently impervious to Covid?


That has been my assumption, which is based on two things.

1. I know a lot of people who have had intense and prolonged exposure to infected people, with no distancing whatsoever, without getting infected themselves. In some cases these people may have had asymptomatic infections, but some have been tested and have no traces of infection or anti-bodies, and in some cases these people have themselves been exposed to other people none of whom got infected. (E.g. I know one husband who had tremendous exposure - close proximity for hours at a time over many days, up to the day when the other guy came out with symptoms - who never showed symptoms, nor did his wife, nor did any members of his parents' family when they moved in for a couple of weeks.)

2. There are differences in infection rate between genders, and other groups. Some of these are explainable in terms of lifestyle, but some are thought to be inherent. This would imply that among groups which get it at lower rates, there are some who have some sort of inherent protection against the virus, and don't get infected in circumstances when members of other groups would.

Of course, this doesn't imply that anyone is 100% immune to getting infected. Only that some people are much less likely to get it than other people, and in circumstances where many people would get infected these people won't.

ISTM that if correct, this would have tremendous public policy implications, in terms of the risk/reward balance at various levels of infection. (For example, suppose you need X% to have been infected and recovered for "herd immunity" if everyone is equally susceptible to getting infected, you might need some lesser percentage if some people are naturally less susceptible.) Question is whether there's some way to quantify this.

Last edited by Fotheringay-Phipps; 05-14-2020 at 03:47 PM.
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Old 05-14-2020, 04:35 PM
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That's one thing researchers are currently studying.
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Old 05-14-2020, 04:57 PM
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I have wondered about this also. I strongly suspect a genetic factor. I am curious as to how this will play out in Europe before it is done.
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Old 05-14-2020, 05:07 PM
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I think with any illness there are people who are "immune". The trick is going to be finding those people, establishing immunity without being completely unethical, and then understanding why they are immune. Those are all pretty big tricks.
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Old 05-14-2020, 05:17 PM
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Almost certainly there are some people who due to genetics are immune to covid-19. But there might not be very many of them.

During the Black Death there were some people very heavily exposed who never got sick.

There are some people today who simply can not catch HIV... but they are rare, only a very tiny percentage of people. (Oddly enough.... some of them are descendants of people immune or recovered from Black Death....)

So yes, probably, but there is no way to know right now how many there might be.
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Old 05-14-2020, 05:21 PM
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One more trick you missed, Sunny Daze: Even if you can figure out why someone is immune, can you use that method to somehow help others?
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Old 05-14-2020, 05:31 PM
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What does the OP mean by "impervious"? Certainly there are people who are infected but asymptomatic. It's not like the virus bounced off them--it's still in there. In fact, this helps the rapid spread of the virus, because so many people don't know that they are infected and passing on the infection to others.
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Old 05-14-2020, 05:59 PM
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I'm not sure if they're inherently (genetically) impervious, but certainly some people are less impacted. That could also be explained because they are younger and healthier or perhaps they were exposed to less of the virus, as there are reports that those who have limited exposure have much milder symptoms than those who lived or worked in close proximity to someone who had it (and didn't know it).
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Old 05-14-2020, 08:47 PM
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Quote:
Originally Posted by Broomstick View Post
Almost certainly there are some people who due to genetics are immune to covid-19. But there might not be very many of them.

During the Black Death there were some people very heavily exposed who never got sick.

There are some people today who simply can not catch HIV... but they are rare, only a very tiny percentage of people. (Oddly enough.... some of them are descendants of people immune or recovered from Black Death....)

So yes, probably, but there is no way to know right now how many there might be.
Is there anyone alive who is NOT a descendant of people who recovered from the Black Death? That is literally millions of people over wide geographical area over 600 years ago. Their descendants surely number close to 100% of humanity by now, and that's only assuming the plague 1340s. There must have been earlier outbreaks in Asia and there were certainly later outbreaks elsewhere.
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Old 05-15-2020, 04:47 AM
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Um... lots of people in the Americas? Did sub-Saharan Africa ever have a plague outbreak before modern transportation? Saharan Africa? The Arctic? Pacific islanders? Native Australians?

Not everyone caught the plague during the plague years, and pre-antibiotics people who caught the Black Death and recovered were not that large, as it had something like a 70% death rate without modern treatment.
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Old 05-15-2020, 05:49 AM
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Quote:
Originally Posted by Broomstick View Post
During the Black Death there were some people very heavily exposed who never got sick.

There are some people today who simply can not catch HIV... but they are rare, only a very tiny percentage of people. (Oddly enough.... some of them are descendants of people immune or recovered from Black Death....)

So yes, probably, but there is no way to know right now how many there might be.
The S Asian subcontinent got fucked sideways by the Spanish flu (compounded by the disinterest of the then ruling British to take any action to ameliorate it), with 10% death rate and 80% in some areas. One hypothesis for the reduced death rate there now and the generally low rate of severe disease is inherited immunity ad a result.
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Old 05-15-2020, 05:52 AM
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Um... lots of people in the Americas? Did sub-Saharan Africa ever have a plague outbreak before modern transportation? Saharan Africa? The Arctic? Pacific islanders? Native Australians?
Recent research suggests that not only did the Black Death hit sub-Saharan Africa, but it was the cause of the breakdown of the trade routes that had existed between it and the MENA region.
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Old 05-15-2020, 08:40 AM
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I wondered this myself. A friend of mine had it and lives in a VERY small house with his wife and two teenage daughters. The kids both worked fast food and were continuing to go to work and one was seeing her boyfriend daily.
When my friend got sick there was nowhere in the house to self-isolate or quarantine so he was amongst his family the whole time. He was the only one in the house to get sick. This was 7 weeks ago.

I know this is anecdotal and but I've heard similar stories so it got me thinking.
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Old 05-15-2020, 08:50 AM
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It is certainly possible, probable even, that some people are immune. I think this is true for virtually every disease except maybe measles.

But in any individual case, it may well be the person who had it was unusually less contagious. We know some people are super spreaders, shedding virus is such massive quantities that the immune systems of those around them are easily overwhelmed. It seems quite plausible that there are less contagious people as well, who are sick but s h ending so little virus that other's immune systems can easily fight it off.

It seems like a distinctive quality in COVID is that severity of symptoms isn't strongly correlated with contagiousness.
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Old 05-15-2020, 09:06 AM
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I think with any illness there are people who are "immune". The trick is going to be finding those people, establishing immunity without being completely unethical, and then understanding why they are immune. Those are all pretty big tricks.
I don't think identifying those people is the point. The real point is how many of such people there are, as a percentage of the population.

Because suppose we find out that 40% of the population has antibodies to the disease (assuming that we can establish that having antibodies makes one immune). Then if we also believe that another 40% don't antibodies because they were never infected but they are immune anyway, then this means that 80% of the population is effectively immune. But if we think only 2% (or 0%) are inherently immune, then we're left with a much lower effectively immune percentage. This has public health ramifications.
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Old 05-15-2020, 09:50 AM
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Um... lots of people in the Americas?
In the 1600s, maybe, but there are comparatively few people in the Americans today without any European, Asian and / or African ancestry.
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Old 05-15-2020, 11:01 AM
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Originally Posted by Fotheringay-Phipps View Post
I don't think identifying those people is the point. The real point is how many of such people there are, as a percentage of the population.

Because suppose we find out that 40% of the population has antibodies to the disease (assuming that we can establish that having antibodies makes one immune). Then if we also believe that another 40% don't antibodies because they were never infected but they are immune anyway, then this means that 80% of the population is effectively immune. But if we think only 2% (or 0%) are inherently immune, then we're left with a much lower effectively immune percentage. This has public health ramifications.
More likely there are people who it affects unusually hard, people who it affects about normally (for COVID-19), and those who it affects unusually mildly, or not at all.

The big question is why the unusual groups are affected those ways- nobody seems to know why some people live through it- it's not even a death sentence for the elderly AND infirm, or why it sometimes kills relatively young and healthy people.

I suspect there's some kind of genetic resistance or unusual susceptability- something that we haven't teased out of the data yet that spells the difference between the various ends of the spectrum. Something much like the way that 10% of people of European descent are effectively resistant to HIV due to genetic mutations that were advantageous for smallpox or plague back in antiquity.
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Old 05-15-2020, 12:54 PM
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Quote:
Originally Posted by Sunny Daze View Post
I think with any illness there are people who are "immune". The trick is going to be finding those people, establishing immunity without being completely unethical, and then understanding why they are immune. Those are all pretty big tricks.
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One more trick you missed, Sunny Daze: Even if you can figure out why someone is immune, can you use that method to somehow help others?
There's a difference between immune and impervious. We are impervious to a lot of corona viruses, and other viruses, that do not infect people, only animals or bacteria. To infect a human, a virus needs to be able to latch onto a human cell and infiltrate it. SARS-CoV-2 binds to human cells with specialized surface proteins shaped into "binding domains" or keys, the spikey bits on the outside of the virus. The key has to match a receptor on the surface of a human cell, usually a certain type of human cell. SARS-CoV-2 binds to the receptor ACE-2. People who are born with oddly shaped ACE-2 cell receptors* can be impervious to those keys. No immune response is needed because the virus can't enter cells.

Identifying people with morphed ACE-2 would not do anyone else any good. Researchers are looking for ways to manipulate the linkage to prevent or reduce cell infiltration.

*usually on lung and gut cells
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Old 05-15-2020, 05:00 PM
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Aaaand, SciShow just posted a YouTube video reporting that researchers are looking for proteins that would latch onto the keys on the virus, leaving them less or nothing to grab a cell with. One candidate protein was discovered by the game Foldit, and it's being tested now. You can play the game, too, if you want to help. Also, the app Folding@home will use your computor to calculate for other proteins that could work. Then your computer could work to fight the virus while you binge watch or sleep.
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Old 05-16-2020, 03:08 PM
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I'm not sure if they're inherently (genetically) impervious, but certainly some people are less impacted. That could also be explained because they are younger and healthier or perhaps they were exposed to less of the virus, as there are reports that those who have limited exposure have much milder symptoms than those who lived or worked in close proximity to someone who had it (and didn't know it).
AFAIK it's generally believed there are at least 4 main factors affecting how serious the outcome
-age
-preexisting health conditions, which tends to correlate with age but isn't the same thing
-viral load
-individual genetics

But like most major questions about COVID the degree of influence of each is still subject a wide uncertainty, especially the last two.

Also there could be significant variation according to individual genetics without anyone being literally immune.

Anecdotally I tested positive for antibodies (from a test with claimed 100% specificity). I probably got it in brief interaction in a crowd at a big public function just before they stopped having those where I live. I was somewhat sick for awhile and it seems to still have a minor effect on my breathing after 2 months, but it wasn't very bad. My wife and I never isolated from each other (I wasn't sure I had it because not all that sick, she wasn't sure she didn't because also had even slighter symptoms, of something) but she tested negative for COVID antibodies. Also a friend tested positive for active infection and recovered, limited isolation possible from husband but he's never had any symptoms (hasn't been tested for antibodies AFAIK). All kinds of explanations for any given one or two situations, but it all seems mysterious still to me.
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Old 05-16-2020, 11:12 PM
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Chao, how is your friend and his family doing now?
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Old 05-18-2020, 01:00 AM
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Question is whether there's some way to quantify this.
I don't think so. There are too many variables. Just extrapolating from a personal experience, when I was young, my mom had me play with kids with chicken pox so I would get it early. I didn't get it. I wasn't immune. I got it as an adult. I don't know why I didn't get it when I was young with multiple exposures, but it didn't mean I was immune.

Just looking at people who don't get it doesn't give enough of an indication. There has to be some testing or screening to determine why people don't get it. That doesn't exist yet, so just observation isn't going to give quantifiable results.
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Old 05-18-2020, 08:08 AM
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Chao, how is your friend and his family doing now?
To date (I just spoke with him last week) he is doing very well. Seems to be completely back to normal which is wonderful as he went into this with some preexisting health issues. (Obesity, high blood pressure, pre-diabetic)
His wife who is on disability due to extreme health issues still has not shown any symptoms of Covid-19 and his daughters are great as well. In fact, his one daughter is 3-1/2 months pregnant and feeling grand.
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Old 05-21-2020, 03:42 PM
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I had two smallpox shots when I was a kid and neither one of them made a mark on my arm. They weren't going to let me into kindergarten until we got a note from the doctor surmising that I was naturally immune. I had the flu in 1957 when I was 5 years old and have not had it since. I do not get a flu shot.

I am now 67 and my attitude is, if I get it, I get it. I've lived a good life and we all are going sometime.
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Old 05-21-2020, 03:56 PM
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I am now 67 and my attitude is, if I get it, I get it. I've lived a good life and we all are going sometime.
Well, we will miss you and a significant fraction of the people you interact with in your daily life.
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Old 05-21-2020, 06:24 PM
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That has been my assumption, which is based on two things.

1. I know a lot of people who have had intense and prolonged exposure to infected people, with no distancing whatsoever, without getting infected themselves..
There is an alternate explanation, which is getting a lot of consideration: Some people just seem to be capable of infecting a lot of other people. If the infected people you know doesn't include one of those "super-spreaders", then you probably won't catch the disease.

If, a lot of the time, you are exposed to a lot of people who are infected, then "probably won't catch the disease from them" won't protect you. In an epidemic situation, even lots of small chances of catching disease adds up. But some of the outbreaks are explosive.

They are trying to put numbers on this, by comparing the number of explosive outbreaks to numbers of single cases. C19 may be somewhere in the middle compared to other diseases. AFAIK there aren't any good explanations for this.
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Old 05-23-2020, 11:30 AM
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Interesting question. I do know that with HIV, there is a small subset of people called "elite controllers" who are HIV-positive, but asymptomatic with an undetectable viral load. However, and it's a big however, being an EC doesn't mean you'll live forever. The last hypothesis I saw was that ECs' immune systems were running all-out to keep a lid on HIV, but eventually, it burns out, so to speak, and the person develops something fairly rapidly fatal like incurable non-hodgkins lymphoma.

Whether experiences with retroviruses like HIV can be directly correlated to a coronavirus remains to be seen.
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