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Another bizarre case of infection...
Posted by: PeterB
Date: April 18, 2020 08:13AM
Not sure if this should be on this side (I'm erring on the side of caution here) and if it's OK to post as a separate thread or if it should be in the sticky above. But here goes...

I just had another of my students report to me that one of her relatives, her aunt, is in bad shape. The peculiar thing is that she was tested a month ago... tested positive, but apparently with no symptoms at that time. (I'm not clear on why she was tested if she had no symptoms; possibly she was with someone who had symptoms and was also being tested, so knew she was exposed and got tested at the same time, or maybe she's a healthcare worker, I don't know.)

So the question becomes...

1) Was the original positive test a false positive, and she got infected later;

2) Did this thing somehow have a month-long incubation period;

3) Did she have it, but have such a mild case as to have essentially no symptoms, but then got reinfected later

... any of these possibilities is more than a bit disturbing.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Another bizarre case of infection...
Posted by: deckeda
Date: April 18, 2020 09:07AM
I have the answers to all three:

"Could be."
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Re: Another bizarre case of infection...
Posted by: deckeda
Date: April 18, 2020 09:09AM
Part of this is that contact tracing really isn't a thing. More of a wish list luxury.

Part of this is we don't know how the virus actually works in "most" scenarios.

Bottom line, she's sick, like so many others.
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Re: Another bizarre case of infection...
Posted by: btfc
Date: April 18, 2020 09:41AM
[amp.cnn.com]
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Re: Another bizarre case of infection...
Posted by: PeterB
Date: April 18, 2020 10:26AM
Quote
deckeda
I have the answers to all three:

"Could be."

Yes, of course ... that's why I listed all three... but as I said, each of the three is concerning in its own way.

Quote
btfc
[amp.cnn.com]

Right, but that's the thing ... those are people who have already had it, who have presumably recovered, who are later testing positive. What I've described is someone who tested positive, apparently without symptoms, who then is showing severe symptoms a month later... not quite the same thing. The doctor in the video clip in your link suggests that the people who've recovered and are testing positive, have "remnants" of the virus left and that's why they're testing positive. (He also says that such individuals are not contagious, but I don't think we know that for sure yet.) It's also possible that there's substantial error in the testing, or that the virus is going dormant, then reactivating. Again, each of these possibilities is disturbing. I'm much more concerned about options #2 or 3 versus #1, since I presume the general accuracy of testing will improve with time.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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Re: Another bizarre case of infection...
Posted by: deckeda
Date: April 18, 2020 11:45AM
The major local news last week was that a 7th Grader was rushed to Nashville (by car) an hour away because he/they/someone was playing with a handgun. Last I heard, doctors didn't want to risk removing the bullet that busted his spinal cord or neck?

And so what have several middle schoolers done? A bunch got together the other day to hang out for a little while and take pictures to share. In the photo they are standing side by side, just like any other day.

Young people truly live forever. Most of my daughter's friends are convinced they either won't get sick or if they do will have total, permanent immunity.

31 cases confirmed how. Each day it creeps up a little more. I'd be shocked if TN's peak was truly April 24, as previously published.
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Re: Another bizarre case of infection...
Posted by: Filliam H. Muffman
Date: April 18, 2020 12:29PM
Quote
PeterB
Quote
btfc
[amp.cnn.com]

Right, but that's the thing ... those are people who have already had it, who have presumably recovered, who are later testing positive. What I've described is someone who tested positive, apparently without symptoms, who then is showing severe symptoms a month later... not quite the same thing. The doctor in the video clip in your link suggests that the people who've recovered and are testing positive, have "remnants" of the virus left and that's why they're testing positive. (He also says that such individuals are not contagious, but I don't think we know that for sure yet.) It's also possible that there's substantial error in the testing, or that the virus is going dormant, then reactivating. Again, each of these possibilities is disturbing. I'm much more concerned about options #2 or 3 versus #1, since I presume the general accuracy of testing will improve with time.

I think this is going to be a really hard thing to track without a lot more forensic testing. It could be she got reinfected with a second strain that went through her local family/community and mutated just enough to bypass her initial response.



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Re: Another bizarre case of infection...
Posted by: JoeH
Date: April 18, 2020 02:58PM
Or the initial response wasn't strong enough to protect at all.

There have been a number of reports of patients getting more than one case connected to COVID-19, I suspect this is going to keep the virologists busy for months or years figuring out the exact aspects of this virus that made it so contagious. Some reports I have seen mentioned 80-85% commonality with the SARS virus of th early 2000s which was not nearly as infectious. Examining those differences is likely to be important.
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Re: Another bizarre case of infection...
Posted by: PeterB
Date: April 18, 2020 04:31PM
Quote
JoeH
Or the initial response wasn't strong enough to protect at all.

There have been a number of reports of patients getting more than one case connected to COVID-19, I suspect this is going to keep the virologists busy for months or years figuring out the exact aspects of this virus that made it so contagious. Some reports I have seen mentioned 80-85% commonality with the SARS virus of th early 2000s which was not nearly as infectious. Examining those differences is likely to be important.

My impression from a quick read of the literature is that a major part of it is the affinity of this particular virus' spike protein for the ACE-2 receptor ... it has an approximately 10-fold higher affinity than the original SARS virus. [www.nature.com]

Edit: one not-very-amusing aspect of the search I just did to find that Nature article (I remembered the figure, but couldn't remember where I read it) is that, unfortunately, the ACE-2 receptors are also found in the Leydig cells of the testes... raising the spectre (admittedly unlikely though) of this virus having another, very unfortunate, side-effect for males.

And yes, I also did consider the possibility of the virus mutating, but apparently this particular virus is not mutating very quickly... only has a few particular, closely related strains, one would hope that the tests are able to detect all the strains. One would also hope that antibodies are likely to be cross-reactive between strains, since they're not likely to differ THAT much.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)



Edited 3 time(s). Last edit at 04/18/2020 04:45PM by PeterB.
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Re: Another bizarre case of infection...
Posted by: AllGold
Date: April 18, 2020 05:52PM
Quote
PeterB
Edit: one not-very-amusing aspect of the search I just did to find that Nature article (I remembered the figure, but couldn't remember where I read it) is that, unfortunately, the ACE-2 receptors are also found in the Leydig cells of the testes... raising the spectre (admittedly unlikely though) of this virus having another, very unfortunate, side-effect for males.

Ruh roh!



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Re: Another bizarre case of infection...
Posted by: Filliam H. Muffman
Date: April 18, 2020 07:10PM
I wonder if people would be having freedom rallies if they knew China designed this virus to attack their balls.



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Re: Another bizarre case of infection...
Posted by: Janit
Date: April 19, 2020 10:30AM
Quote
PeterB
My impression from a quick read of the literature is that a major part of it is the affinity of this particular virus' spike protein for the ACE-2 receptor ... it has an approximately 10-fold higher affinity than the original SARS virus. [www.nature.com]

I wonder, though, if it will turn out to be more complex than the ACE-2 affinity. These questions come to mind:

Why are so many COVID-19 cases mild or asymptomatic, when SARS appears to hit all it's victims very hard (and is this understanding of SARS correct)?

Is there a difference between COVID-19 and SARS outcomes once they get into the lungs? At what stage is the difference most dramatic?

Do the spike proteins of the two viruses have different abilities to elicit a fast and effective immune response?
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Re: Another bizarre case of infection...
Posted by: Ca Bob
Date: April 19, 2020 10:38AM
Quote
Filliam H. Muffman
I wonder if people would be having freedom rallies if they knew China designed this virus to attack their balls.

Winner of the internet award for the week.
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Re: Another bizarre case of infection...
Posted by: PeterB
Date: April 19, 2020 12:57PM
Quote
Janit
Quote
PeterB
My impression from a quick read of the literature is that a major part of it is the affinity of this particular virus' spike protein for the ACE-2 receptor ... it has an approximately 10-fold higher affinity than the original SARS virus. [www.nature.com]

I wonder, though, if it will turn out to be more complex than the ACE-2 affinity. These questions come to mind:

Why are so many COVID-19 cases mild or asymptomatic, when SARS appears to hit all it's victims very hard (and is this understanding of SARS correct)?

Is there a difference between COVID-19 and SARS outcomes once they get into the lungs? At what stage is the difference most dramatic?

Do the spike proteins of the two viruses have different abilities to elicit a fast and effective immune response?

I'm going to do some educated speculation here -- answering your questions in order:

1) I'm guessing that there are LOTS of other factors at play in terms of the host's clearance of this virus. The spike protein allows entry, but once the virus is in, the host can try to eliminate it in a variety of ways. And my understanding of SARS is that, yes, it did seem to hit most of its victims hard, compared to SARS-CoV-2, which seems much more variable from person to person. Here is a nice rundown of all the proteins we're talking about:
[www.nytimes.com]
(sorry for paywall)

2) See my answer to #1. I can imagine that some people eliminate the virus in its early stages, before the spike protein can even do anything; yet others eliminate it once it's inside the cell, and yet others eliminate the infected cells relatively quickly. Other people (especially the elderly and immunosuppressed) have a crappy immune response and end up on a ventilator. Again, some nice rundowns of the infectious process:

[www.youtube.com]
[www.youtube.com]
[www.youtube.com]

3) I'd bet that if the spike protein is not very high affinity for the receptor, then normal lung clearance mechanisms will get rid of it, before it has a chance to infect. But you're right, it's also possible that the SARS vs. SARS-CoV-2 spike proteins could differ in immunogenicity and therefore the host's ability to fight off the infection, once it's established.

My overall suspicion is that there are a LOT of host factors that we've just begun to look at, as well as variation between viral strains... unfortunately, the virus being a moving target.




Freya says, 'Hello from NOLA, baby!' (Laissez bon temps rouler!)
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