
Coronavirus protective immunity is short-lasting [pdf] - metafunctor
https://www.medrxiv.org/content/10.1101/2020.05.11.20086439v2.full.pdf
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lbeltrame
Notice that this is for common coronaviruses, and doesn't mention SARS or MERS
much: IIRC, the former elicited an IgG response years after exposure in an
experiment. As far as I can tell, this preprint does not cite that work.

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arcticbull
Indeed -- studies of SARS have something different to say. Here's one study
that shows duration of antibody response to SARS is at least 3 years [1].
Here's a study that shows T cell response for at least 6 years [2].

MERS had a much, much higher fatality rate (~35%) and infected a small handful
of people (~2500) so it's harder to get meaningful data.

[1]
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/)

[2]
[https://www.jimmunol.org/content/186/12/7264.short](https://www.jimmunol.org/content/186/12/7264.short)

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tim333
And more:

>Two findings emerge: first, the T cells generated back then are still active
17 years on. And second, those old T cells offer protection against the new
coronavirus. [https://www.telegraph.co.uk/health-fitness/body/no-
antibodie...](https://www.telegraph.co.uk/health-fitness/body/no-antibodies-
could-still-have-had-covid-fighting-t-cells/)

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quicklime
It might be worth pointing out that this study is about coronaviruses in
general, not the coronavirus that causes COVID-19 (SARS-CoV-2).

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asdfasgasdgasdg
Also worth noting that strain is not controlled for in this study. The study
acknowledges at the end that reinfection may be by different strains. Under
the same parameters as this study it could be said that flu infection doesn't
confer immunity. But, it does, just there are a lot of distinct strains of
flu.

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pritovido
This is for common coronavirus but something very important must be
remembered: The reinfection is not the same.

The first time you face a new virus, you don't have antibodies. You also have
no information to generate them. Generating this information takes a long
time, which is dangerous.

If you reinfect again after 12 months, you don't have antibodies, but there
are cells that contain the information to regenerate the antibodies much
faster than the first time you faced the virus.

So reinfection is not as dangerous as the first time.

~~~
war1025
> The reinfection is not the same

As a parent of young kids who manages to catch the stomach flu at least once a
year from them, this is something I've come to appreciate a ton.

The first time we caught it after neither me nor my wife having caught such a
thing for over a decade, it knocked us out for two days. Just completely
miserable.

Now, four years and half a dozen rounds later, it's still terrible, but only
lasts twelve hours or so.

Gotta love the immune system.

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Grimm1
We already knew this about the general family of coronaviruses, but MERS and
SARS both generated longer immune responses.

I imagine we're starting to look at people who had severe cases in March, and
survived to see if their immune responses are still holding up 3-4ish months
after and will be doing so for the months to come.

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_wldu
T cells also play a big part in long term immunity.

[https://www.sciencemag.org/news/2020/05/t-cells-found-
covid-...](https://www.sciencemag.org/news/2020/05/t-cells-found-
covid-19-patients-bode-well-long-term-immunity)

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gojomo
Mild reinfection without symptoms (& in all likelihood, decreased shedding) is
functionally nearly the same as actual "immunity".

In a dynamic long-term analysis, such mild reinfections might even be for-the-
best: it refreshes your immune response, and those around you in a similar
situation, as if the virus itself had been turned into a naturally-circulating
seasonal "booster shot".

What if the other four known 'common cold' coronaviruses were all just as
challenging as Covid-19 when they emerged... but nowadays, everyone gets them
1st when young – & their immune system most able to adapt – thus rendering
them relatively mild, or even undetectable, on all subsequent re-exposures
over an entire lifetime?

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m0zg
Is anyone else worried that there won't actually be a usable vaccine for C19?
After all, we don't have a vaccine for any other coronavirus. What makes
people think we'll have it for this one, let alone "within a year"?

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slavapestov
We don't have a vaccine for any other coronavirus because it's not really
worth it; most people with the common cold coronaviruses only have mild
symptoms. A SARS 1.0 vaccine was in development at one point, but they stopped
because the virus was eradicated.

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m0zg
> most people with the common cold coronaviruses only have mild symptoms

Pretty sure the same could be said of C19, depending on how you define "most".
However, cursory googling shows that there are _1 billion_ cases of common
cold in the US alone every year (lots of people have it more than once), so
it'd still seem like it'd be worthwhile if it were doable. Common cold
accounts for 40% of all time lost from jobs and 30% of lost school time.

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war1025
Only a minority of colds are caused by Cornaviruses though. Something like 20%

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m0zg
That's still 200M in the US alone.

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graeme
There are at least four coronaviruses that cause the common cold. And immunity
lasts only 6-12 months. So, this would be 4-8 vaccinations per year, for life,
to reduce colds by 20%.

I might do that myself, but I’m not sure it would sell well enough to fund the
costs of developing the vaccine.

