There's "no evidence" coronavirus survivors can't be reinfected, WHO

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  • #1
Evo
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I know Dr Fauci said that the virus might mutate by September and that we are likely to see another round of the virus then (if we have a reprieve in the summer). But I've been reading that they don't know if people that have had the virus are immune for weeks, or months. It's not very reassuring since we don't even have the first version of a vaccine yet. I know viruses mutate, which is why we have to have a new flu vaccine every year based on what they think will be effective.

So, what are the plans? Just forget the quarantines and what we're going through right now? I mean, yes, it does keep infection down, but it's financially devastating to many. Just accept that this is the new norm?

There's "no evidence" Coronavirus survivors can't be reinfected, WHO says

The World Health Organization (WHO) said there is "no evidence" that survivors of COVID-19 cannot be reinfected with the virus. In a statement Saturday morning, WHO warned that antibodies may not adequately protect survivors, leaving them vulnerable to a second Coronavirus infection.

https://www.cbsnews.com/news/corona...U0yjmwQ8b_-4YtwzY5hU8NQ-jaMAY6t-tyVM3072C74kY
 

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  • #2
phinds
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I saw a medical talking head on TV who said, yes the WHO statement is true but it is very restrictive and correctly waiting for overwhelming evidence before making any definitive statements. He added that it DOES seem we have enough evidence to know that it is at least likely that immunity will be there (at least for a year or two). I don't know anything about his reliability but at least it wasn't on Fox "News"
 
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  • #3
Evo
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I saw a medical talking head on TV who said, yes the WHO statement is true to it is very restrictive and correctly waiting for overwhelming evidence before making any definitive statements. He added that it DOES seem we have enough evidence to know that it is at least likely that immunity will be there (at least for a year or two). I don't know anything about his reliability but at least it wasn't on Fox "News"
But if the virus mutates, then you won't have immunity to the "new" version, just the old. Correct? And when will we know the virus has mutated, it is so varied right now, mild cases such varied symptoms, now they're saying blood clots, organ damage and strokes occurring in those that had been thought to have been cured of the virus.
 
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phinds
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But if the virus mutates, then you won't have immunity to the "new" version, just the old. Correct?
Very likely that's correct. Mutations seem to happen because of a reaction to medicine or bodily rejection, which is why antibiotics have become less effective than they used to be. Damn smart little bugs "figured out" how to get around them.
 
  • #5
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Very likely that's correct. Mutations seem to happen because of a reaction to medicine or bodily rejection, which is why antibiotics have become less effective than they used to be. Damn smart little bugs "figured out" how to get around them.
No, no, no, it's a virus. No antibiotics. :wink:
 
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BillTre
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The virus genome encodes a number of different proteins with different functions in different parts of the genome.
The genome is mutating all the time at some relatively low level.
Most of those changes in the genome will not affect the parts on the outside of the virus which are those that interact with antibodies (they come from the outside).
Other genome changes will affect other aspects of the viruses behavior, like maybe: what tissues it goes to, or how long it takes to replicate, or some other aspect of its functioning. those won't directly affect whether antibodies will still be able to bind to their target molecules (on the surface of the virus).

All of these different mutations can be identified by comparing the entire genome sequence of lots of different viruses. These different mutations can be used to identify variants which can then be traced through the world as different variants (usually randomly) invade different places. That is our current use for them.

You can't tell if immunity is going to work or for how long until a significant number of people have recovered and then been re-exposed to the virus. Therefore early in the history of a new infection, it is tru that these things are not empirically known. However, it could be a false negative absed on not having any evidence either way.
There are lots of other details that are not yet known, like what is the difference between the immunity that develops in someone who had a weak infection vs. someone who survived a very bad infection, how long do the antibodies last in an individual, are those antibodies effective in preventing reinfection?, if not why did the person recover, ...

Too soon to worry.
 
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  • #7
atyy
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I think the WHO is not so much concerned with the vaccine, but more concerned with the increased use of antibody tests, which may have a high false positive rate. This may lead to people with not even partial immunity to behave as if they cannot get the disease and cannot infect anyone else. I should point out we don't even know the false positive/negative rate of the PCR tests, which are generally thought to be more reliable than the antibody tests.
https://www.nytimes.com/2020/04/24/health/coronavirus-antibody-tests.html
https://www.evaluate.com/vantage/ar...-19-antibody-tests-face-very-specific-problem
https://www.fiercebiotech.com/medtech/current-covid-19-antibody-tests-aren-t-accurate-enough-for-mass-screening-say-oxford

From SARS we suspect that people who have recovered should have immunity for a year or so (not because the virus mutates, but because the body produces less antibodies over time), but the WHO is strictly correct that we don't know this for COVID-19. In the other thread @Ygggdrasil pointed to some interesting papers in which the level of particular antibodies was low in some people with a mild disease; but these papers pointed out that the antibodies examined by the assay may not be the only mechanisms contributing to immunity in some people.
https://www.bbc.com/future/article/20200421-will-we-ever-be-immune-to-covid-19
""Antibodies are not the only answer," says Iwasaki. "We don’t know why the people recovered but I suspect it was because they had a very good T cell response.""

With respect to a vaccine, most people think that the mutation rate of the virus will not affect the effectiveness of a vaccine for a few years, because there are currently very few mutations in the spike protein, which is the part of the virus most vaccine-development efforts hope to use to induce immunity.
 
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  • #8
Borek
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My understanding is that lack of long term immunity has nothing to do with virus mutations - it is immunology thing. Some viruses induce immunological answer that is permanent (or at least long lasting), some don't. Virus mutations can add to troubles, but are not required.

And if that's the problem here, than vaccine - which triggers exactly the same immunological response, just without the illness itself - won't produce long term immunity for the same reasons. If so, it will probably require some reshooting regime (say, every year, or every two years) to keep us safe.
 
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  • #9
Ygggdrasil
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Current evidence suggests that the mutation rate of the virus is slow enough that we should not expect that the virus will mutate to avoid immunity. Of course, mutations can be unpredictable, so mutation to avoid immunity is always a possibility, though something that can be monitored.

In studies with monkeys, infection with COVID-19 provides immunity to the disease in the short term, suggesting that re-infection is unlikely or rare and that a vaccine should be able to produce immunity. A bigger concern may be that our body's immune response to the virus can wane over time. Our experience with the four other endemic coronaviruses suggests that immunity to these viruses wanes over time, and studies on people who were infected by the similar SARS virus from the 2003 outbreak also suggests that levels of antibodies against the virus wane over the course of a few years. A non-peer-reviewed pre-print looking for the presence of antibodies in the blood of those with confirmed COVID-19 infections found that up to ~1/3 had low or no detectable antibodies (mostly from people who had mild cases), which could be a concern for the possibility of re-infection. However, as @atyy mentioned, it is not clear whether these antibody tests truly reflect immunity, and it is possible that some of the people with low/no detectable antibodies still have immunity, but the particular test is not able to detect the antibodies.

Here's a good summary of what we know regarding immunity to COVID-19 from STAT news: https://www.statnews.com/2020/04/20...nity-and-antibodies-and-plenty-we-still-dont/
 
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  • #10
Dr. Courtney
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I've been working hard to keep myself out of high risk groups for almost a decade. Many people focus on short term, easy ways to avoid disease like masks and vaccines and isolation. I focus more on long term practices to keep my immune system healthy and my body more resistant to disease.

For example, most type 2 diabetes patients are in their circumstance due to behavioral choices over a long period of time. This puts them at much higher risk of COVID-19 and lot of other illnesses.

On the whole, I will continue to practice social distancing at about the same level I am now as long as COVID-19 numbers in my county are as high as they are now. For me, that means over a 90% reduction in social interactions, not going to restaurants, minimizing time at places like Walmart, keeping the 6 ft spacing, trying not to touch common objects in public, and so on at least through the end of May.

But that level of isolation is probably not sustainable indefinitely (or in repeated cycles for months out of every year) for me or for most Americans. At some point, we'll have to depend more on being healthy, caring for our immune systems, and some practices (like not shaking hands) that are more sustainable indefinitely.
 
  • #11
atyy
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While the WHO statements referred to in the OP were strictly correct, they conveyed an helpful perception. The WHO has since removed that statement, and replaced it with clarification that people who recover can expect some level of protection from re-infection for some time. Although the earlier statement has been removed, its main concern about the possible the false positive rate of immunity tests remains important.
 
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  • #12
StatGuy2000
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As someone who works within the health care and pharmaceutical/biotechnology sectors, and have worked specifically on infectious diseases among other areas, what the WHO states is correct in the sense that we do not have evidence of the extent of the immunity for those who have recovered from COVID-19.

It is generally understood that patients (especially those who are otherwise healthy and do not have compromised immune systems) who recover from any infectious disease will develop antibodies specific to the pathogen that the patients were infected to (e.g. influenza, measles, or for SARS-CoV2, the Coronavirus that leads to COVID-19), and these antibodies confer immunity to at least some extent.

What is not known are the following:

1. The duration of the immunity -- is the immunity conferred by recovery from COVID-19 lifelong (e.g. recovery from mumps), or will immunity wane after a period of time.

2. To what extent any mutation within the SARS-CoV2 virus could lead to a decline or loss in immunity to those who have survived and recovered from a previous COVID-19. It is possible that certain mutations could lead to COVID-19 recovered patients to become reinfected. However, from what I understand, any such patients will more than likely suffer much milder illness as their immune systems will be able to "recognize" the virus and will be able to fight off the infection, even though not sufficiently to prevent illness. After all, much of the severity we see with COVID-19 is due to the population being "immunologically naive" due to the novel nature of the SARS-CoV2 virus.

As others have already stated, points #1 and #2 will likely not be known until more people recover from COVID-19. So I feel that the WHO is being conservative in their statements about this, and basing any statements on the best scientific evidence.

So I do not feel that we need to add to the worry beyond what we are currently facing this pandemic.
 
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  • #13
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https://www.msn.com/en-ca/news/world/a-mutant-coronavirus-has-emerged-even-more-contagious-than-the-original-study-says/ar-BB13DH2x?OCID=ansmsnnews11
Mutation:
Scientists have identified a new strain of the Coronavirus that has become dominant worldwide and appears to be more contagious than the versions that spread in the early days of the COVID-19 pandemic, according to a new study led by scientists at Los Alamos National Laboratory.

The new strain appeared in February in Europe, migrated quickly to the East Coast of the United States and has been the dominant strain across the world since mid-March
Italy was one of the first countries to see the new virus in the last week of February, almost at the same time that the original strain appeared. Washington was among the first states to get hit with the original strain in late February, but by March 15 the mutated strain dominated. New York was hit by the original virus around March 15, but within days the mutant strain took over. The team did not report results for California
 

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