Author Topic: Dropping Antibody Levels  (Read 21525 times)

Offline AsherO

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Re: Dropping Antibody Levels
« Reply #150 on: May 15, 2020, 06:30:34 PM »
As someone who is learning this stuff right now, I can tell you all that immunology is frighteningly complex, and unless anyone in this thread has expert knowledge in it (and can interpret things like this: https://www.biolegend.com/Files/Images/BioLegend/pathways/ImmPoster.jpg), I suggest that this is all an exercise in futility.

+1000

Armchair epidemiology is several orders of magnitude easier than armchair immunology.

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Re: Dropping Antibody Levels
« Reply #151 on: May 15, 2020, 06:34:03 PM »
Thanks!
These are the posts that make DDF shine. I think @biobook has the most "posts with substance" ratio.

Offline chevron

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Re: Dropping Antibody Levels
« Reply #152 on: May 15, 2020, 06:40:14 PM »
As someone who is learning this stuff right now, I can tell you all that immunology is frighteningly complex, and unless anyone in this thread has expert knowledge in it (and can interpret things like this: https://www.biolegend.com/Files/Images/BioLegend/pathways/ImmPoster.jpg), I suggest that this is all an exercise in futility.

I have never said that I know anything and I have quoted many great doctors who said that the more they understand about the virus the more they realize that they don't understand anything.

I haven't been trying to be a fear monger I'm trying to get people to just try to understand that we don't know what we're dealing with and we should be careful.

I'm making no attempt to scare people I'm making attempt to wake people up to various things or some of them known some of them unknown that's all
« Last Edit: May 15, 2020, 06:53:51 PM by chevron »

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Re: Dropping Antibody Levels
« Reply #153 on: May 17, 2020, 01:20:37 AM »
This is not my field, but here's how I understand it:
The graph is just meant to show how symptoms and antibodies change over time, but is not showing real data (note the lack of numbers on the y-axis and the Disclaimer below the graph).  The red line shows that IgG decreases after the infection has been fought off, then the line stops in midair. It doesn't necessarily mean that the levels plateau there, just that nobody knows exactly what will happen next.  Like the edge of medieval maps, where dragons and sea-serpents indicated that nobody really knows what's beyond this point.  It IS normal for the body to stop wasting energy producing a specific antibody when it's no longer needed, but it's not yet known how quickly the levels will go down, how far, for how long, etc.

The text on the graph seems a little misleading, where it says "IgG provides long-term immunity".  The ability to fight off future infections does not occur because of the presence of those antibodies in the blood, but rather because of the presence of memory B cells, which "remember" how to produce that particular antibody.   

During the first infection, antibodies are produced to fight the infection, which (in this graph) took about 12 days to reach an effective level, and in the interim, the virus caused disease symptoms. 

In a second infection, the memory B cells pour out IgG antibodies immediately, reaching an effective level so quickly that the virus is neutralized before symptoms can appear.  So IgG IS involved in long-term immunity, but it's not the remaining antibodies from the first infection, but rather similar, newly-produced IgG antibodies.

This is diagrammed on Fig. 2 on this page, don't know how to insert:
https://courses.lumenlearning.com/wm-biology2/chapter/immunological-memory/

So this might be what yeshivabucher expressed in other words:

As someone who is learning this stuff right now, I can tell you all that immunology is frighteningly complex, and unless anyone in this thread has expert knowledge in it (and can interpret things like this: https://www.biolegend.com/Files/Images/BioLegend/pathways/ImmPoster.jpg), I suggest that this is all an exercise in futility.
As you guys sound pretty knowledgeable maybe you can explain for the the simple guys what would prove immunity and why a lot of Doctors are saying it might take a long time to prove it
For example say its memory B cells you need can’t someone be tested for their presence?

Offline biobook

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Re: Dropping Antibody Levels
« Reply #154 on: May 18, 2020, 07:19:59 PM »
Most of what I know about coronavirus I've learned through DD, so I'm sure there are many here more knowledgeable than me!  But I'll try to provide an answer of sorts to what I think you're asking, and perhaps others can correct it.

A test for B memory cells wouldn't necessarily get you the information you want, because, for example, one could have B memory cells that are physically present, but that are not functioning properly to produce sufficient antibodies.  What you really want is not to know your level of B cells or any of the other cells and molecules in the fascinating poster that Eru Ilúvatar posted, but rather to know whether you're immune to a second infection of coronavirus.  And rather than answering this by dissecting and analyzing all the components of your own immune system, it makes more sense to answer this for the general case:  Do humans develop immunity to this coronavirus after a first infection?

Answering this would take a long time, as the doctors have told you.  If you want to know whether people are immune for two months or 6 months or 1 year or 2 years after their first infection, then obviously you have to wait two months or 6 months or 1 year or 2 years to get your answer.   There are two ways to study this:

1. Experimental:  Take a group of people who have recovered from Covid-19, infect them with the virus, and watch them over the next two weeks to see whether or not they get sick with Covid-19 a second time.

This kind of deliberate infection research has been done in the past, most famously when Nazi doctors infected people with tuberculosis or typhoid, and took careful scientific notes as they watched the infected people get sicker and sicker and finally die.  The post-war trial that disclosed this research horrified the world, not because it was worse than other Nazi atrocities, but because it was conducted by doctors who had taken an oath to use their skills in healing.  In response, international and national guidelines were composed that now regulate research on human health. 

To do this sort of experiment today, researchers would first need to decide on the exact details of the protocol they will use, including:
What people will you test?  Males, females, or both?  Young, old, or both?  Those who had severe symptoms, mild symptoms, no symptoms, or all of these?  Those who were treated with particular medications?  Those who had tested positive for the virus only, for the antibody only, or both? Etc.
How will you infect them?  Inject them with the virus, or spray it on their face with a sneeze-machine?
Which virus will you use?  Several mutated versions are known to exist already. 
What dose of the virus will you use?  If nobody gets sick, you won't know whether that's because they're immune, or whether you used too small of a dose to cause disease.  If you use too large a dose, and people are not sufficiently immune, you might cause an especially severe disease response.
If people DO get sick after this second infection, how will you treat them?  There are ethical issues in infecting someone with a potentially fatal disease before we have clearly effective treatments.
How will you obtain informed consent?  This means that anyone who participates in the experiment has to agree that they are doing so voluntarily, and have been informed of what might happen to them as a result of this participation.  For example, they might have a slight reaction at the site of the injection, but not get sick beyond that.  That of course is what we're hoping for, and it certainly would be great if that's the result. It's also possible that immunity does not develop, and the people will develop Covid-19 a second time. That would be annoying to go through that again, but at least people know what they're getting into.  But there's a third possibility, which is that following the second infection they will have a worse reaction than the first time.  Perhaps their immune system was partially weakened the first time, and now they are less able to cope and develop a more severe case.  Perhaps they had slight unnoticeable changes to the blood vessels the first time, and with the second infection, they are more likely to develop clotting disorders.  As far as I know, these last possibilities just exist in my imagination, but the point is that the researchers would have to consider all the things that might go wrong, and notify the participants in the experiment of these in advance.

After the researchers have figured out all these and other details, they would have to send this protocol to a review board, which would discuss whether the experiment, as proposed, is ethical and whether it is likely to lead to significant findings.  They might ask for changes, or they might turn it down entirely.  Or they might approve it, at which time the researchers would start looking for people willing to be subjects in the experiment. 

There are probably researchers considering this sort of experiment, but the process above could take weeks or months, so the rest of us won't hear about it until they announce that they're looking for subjects. 

2. Observational.  The second way to determine immunity is to simply wait for people who've recovered from Covid-19 to leave home and lead more normal lives, during which time some of them will inevitable come in contact with the virus again.  People who get sick with Covid-19 will be asked about their previous infections and previous positive tests for the virus or antibodies, and researchers will be able to analyze how many, if any, of the new Covid-19 cases are in people who had an earlier confirmed Covid-19 infection.  If no new infections occur in those who've had confirmed Covid-19 in the past, then we can assume that a first infection causes immunity. 

Again, if those with previous infections don't get sick for two months, we'll only know that immunity lasts two months.  It will take longer to find out whether this immunity is longer-lasting.

This study will take longer than the previous one, because you have to wait for people to incidentally meet up with a virus somewhere, rather than infecting them deliberately all at once, but it can be started more quickly.  In fact, it's started already.  We've heard of a few cases in China and South Korea that suggested that a recovered patient had gotten sick a second time, and researchers there are trying to figure out exactly what that means. Is this really a second infection, or a continuation of the first?  Was the first infection really the flu? There will undoubtedly be more such cases in the US as people increase their social activity.


Offline Dan

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Re: Dropping Antibody Levels
« Reply #155 on: May 18, 2020, 07:29:30 PM »
We've heard of a few cases in China and South Korea that suggested that a recovered patient had gotten sick a second time, and researchers there are trying to figure out exactly what that means. Is this really a second infection, or a continuation of the first?  Was the first infection really the flu? There will undoubtedly be more such cases in the US as people increase their social activity.
Or are they people whose bodies just don't produce lasting immunity?

Love your posts by the way!
Save your time, I don't answer PM. Post it in the forum and a dedicated DDF'er will get back to you as soon as possible.

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Re: Dropping Antibody Levels
« Reply #156 on: May 18, 2020, 07:33:32 PM »
Or are they people whose bodies just don't produce lasting immunity?

Love your posts by the way!
I thought someone posted an article here saying that the Korean cases were false positives or dead RNA or something like that.

+1!
Feelings don't care about your facts

Offline biobook

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Re: Dropping Antibody Levels
« Reply #157 on: May 18, 2020, 07:51:11 PM »
Thanks, Dan!  Likewise!

Yes, those possibilities, and more (no immunity after the first infection, or the first infection was a false positive, etc.)

My point was only that when studying this experimentally, you can take 1000 people today, selected for having a particular prior experience, infect them in a controlled setting, and get a pretty clear-cut answer in a few weeks.

When you wait for people to become infected naturally, the new cases dribble in, one by one, each one with different prior experiences.  And each one has to be analyzed to figure out exactly what had been going on with them in the first and second infections, and so this will take much longer to get an answer.

Offline presidentialplus

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Re: Dropping Antibody Levels
« Reply #158 on: May 19, 2020, 06:37:19 PM »
Anything could be.........

But antibody are only developed a few weeks in to the virus.
If you could still be spreading the virus while having anti bodies then the virus is contagious for more then a month. Something nobody says.
You could test positive for weeks after the virus is gone. It's from dead cells.
 


Wrong.

Next...

https://www.bloomberg.com/news/articles/2020-05-19/covid-patients-testing-positive-after-recovery-aren-t-infectious

Still Wrong?

Next?

« Last Edit: May 19, 2020, 06:40:33 PM by presidentialplus »

Offline S209

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Re: Dropping Antibody Levels
« Reply #159 on: May 19, 2020, 07:19:56 PM »

https://www.bloomberg.com/news/articles/2020-05-19/covid-patients-testing-positive-after-recovery-aren-t-infectious

Still Wrong?

Next?


Where was this confirmed? Last I checked it was a theory that many doctors were assuming (hoping?).
Perhaps the theory was now confirmed :)
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Offline chevron

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Re: Dropping Antibody Levels
« Reply #160 on: May 20, 2020, 01:27:57 AM »
Thanks, Dan!  Likewise!

Yes, those possibilities, and more (no immunity after the first infection, or the first infection was a false positive, etc.)

My point was only that when studying this experimentally, you can take 1000 people today, selected for having a particular prior experience, infect them in a controlled setting, and get a pretty clear-cut answer in a few weeks.

When you wait for people to become infected naturally, the new cases dribble in, one by one, each one with different prior experiences.  And each one has to be analyzed to figure out exactly what had been going on with them in the first and second infections, and so this will take much longer to get an answer.

Right but as a friend told me, it's possible to have the virus multiple times in mild form, this would likely mean that the person didn't develop immunity to it ?

Offline PlatinumGuy

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Re: Dropping Antibody Levels
« Reply #161 on: May 20, 2020, 04:02:37 AM »
Thanks, Dan!  Likewise!

Yes, those possibilities, and more (no immunity after the first infection, or the first infection was a false positive, etc.)

My point was only that when studying this experimentally, you can take 1000 people today, selected for having a particular prior experience, infect them in a controlled setting, and get a pretty clear-cut answer in a few weeks.

When you wait for people to become infected naturally, the new cases dribble in, one by one, each one with different prior experiences.  And each one has to be analyzed to figure out exactly what had been going on with them in the first and second infections, and so this will take much longer to get an answer.
To the best of my knowledge there is no such thing as a false positive PCR test. There may be an error in processing, but the test sees the physical virus so it cannot be false. It may have already been overcome by the immune system and no longer transmissible, and this can only be determined by plaque assay (to quantify plaque forming units) which is how the Korean study reached the conclusion the reinfected patients were not contagious.


Darpa funded research:

https://www.publichealth.columbia.edu/public-health-now/news/risk-coronavirus-reinfection-remains-after-recovery


(If my understanding is correct, over 90% of the general population already has these antibodies, and the specific COVID tests are only detecting an elevated number, so there is less indication B cells have newly developed antibody production capabilities they can memorize)
« Last Edit: May 20, 2020, 04:28:19 AM by PlatinumGuy »
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Offline biobook

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Re: Dropping Antibody Levels
« Reply #162 on: May 20, 2020, 01:28:37 PM »
Thanks for this very interesting article! 

It does say that 90% of people have antibodies to coronavirus, but they mean the general class of coronavirus, not  the novel coronavirus that causes covid-19.   

The body fights infections by making antibodies that can neutralize a particular infectious agent, so each antibody is made to neutralize a very specific bacteria or virus. (In rare cases, an antibody may "cross-react" with something else, but we'll ignore that for now.)  So for the 4 different types of coronaviruses they studied, there were 4 different types of antibodies, each with a somewhat different structure.  These coronaviruses have been going around for years and cause typical cold symptoms, especially in children.  They did this study in 2016-2018, and apparently published it now because it might give us an indirect clue about what to expect for the novel coronavirus. 

Of 86 people who had a positive nasal swab test for one of those 4 coronaviruses, 12 had a second positive test for that same  coronavirus within the next year or so, indicating that they were re-infected.  One second positive test occurred just 4 weeks after the first, but most were 9-12 months later. 

So the bad news: This suggests that immunity to a coronavirus may last less than a year, so it's worrying that this might be true for the novel coronavirus, too. 

The more hopeful news:  Only 12 of the 86 (14%) people who got sick were reinfected, so perhaps immunity lasts longer for most people.  And re-infections occurred for only 3 of the 4 coronaviruses they looked at, so perhaps some coronaviruses produce a longer-lasting immune response.  Remember they only looked for about a year, so we don't know how long immunity lasts for that 4th coronavirus they studied.  But it at least raises hope that the novel coronavirus might produce longer-lasting immunity.

The somewhat-good news:  In their records of the cold-symptoms people reported over this time, they found that people who got sick twice had similar symptoms both times.  If they had a mild cold the first time, they had a mild cold the second time.  If they had a severe cold the first time, they had a severe cold the second time.  Interestingly, those who were asymptomatic with the first infection, were asymptomatic with the second infection.  So it's reassuring to hear that the re-infection did not cause worse symptoms the second time around.  And if we extrapolate to the novel coronavirus, it makes us hopeful that those who have a positive virus test but had no symptoms, may really be unlikely to get infected in the future.

Interesting news:  Some families (children and parents) reported mild symptoms, others families had more severe symptoms.  The researchers think severity of disease depends on some unknown genetic factors.

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Re: Dropping Antibody Levels
« Reply #163 on: May 20, 2020, 01:44:41 PM »
Hit it out of the ballpark again!

@biobook What is your educational/work background?

Offline Iz

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Re: Dropping Antibody Levels
« Reply #164 on: May 20, 2020, 02:33:39 PM »
And the great news: nobody will die twice.