
Spain's coronavirus antibodies study adds evidence against herd immunity - ceejayoz
https://edition.cnn.com/2020/07/06/health/spain-coronavirus-antibody-study-lancet-intl/
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vikramkr
A few things to remember. Antibodies dont stay expressed for high amounts for
long levels of time forever after infection - imagine if your body was 100%
against every infection you ever encountered forever? The important factor is
that your body _remembers_ what antibody to make and then makes it when the
next infection happens. Depending on the sensitivity of the test you might not
see a response. And a second important point - antibody mediated immunity is
just one form of immunity. Cell mediated immunity definitely plays a role
against coronavirus [1] and this doesnt test for the presence of reactive T
cells etc. We arent getting a complete picture.

Also, if 5% of people have been infected, and all of them make antibodies,
then that means herd immunity is still reachable. We dont have the data we
need to figure out the complete fraction. And of course, a vaccine will help
us artificially boost our way to herd immunity.

[1] [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)

~~~
ceejayoz
> Also, if 5% of people have been infected, and all of them make antibodies,
> then that means herd immunity is still reachable.

A low rate of antibody prevalence in hard-hit Spain would indicate reaching
herd immunity (without overwhelming healthcare systems) would take quite a few
years, though.

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DanBC
[https://twitter.com/ashishkjha/status/1280159343384518656?s=...](https://twitter.com/ashishkjha/status/1280159343384518656?s=20)

> A few other things stand out:

> Spain has 297K official cases -- so this represents about 8X that count
> (population 47M X 5.0%)

> Spain with 28,400 deaths -- so if we assume 5% seroprevalence....

> Gives us an Infection Fatality Rate of 1.2% in Spain

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rurban
On the other hand Germany antibody tests provide evidence for herd immunity.

There's no country yet which reached herd immunity, but antibody tests in
several central and east European countries with its low infection rates,
provide evidence that previous similar "Schnupfen" (cold) outbreaks provided
enough antibodies to fight it off.

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Fjolsvith
All of a sudden, we need herd immunity against a flu virus? Have we ever had
herd immunity against a coronavirus?

~~~
ceejayoz
1\. It's not a flu virus. (Some coronaviruses cause colds; none are
influenza.)

2\. It's entirely possible any number of coronaviruses in the last few million
years have been eliminated from humans via herd immunity. The faster the
spread, the more likely herd immunity.

~~~
rurban
First the flu is not a virus, it's an illness (combination of symptoms) caused
by an influenza virus. Since the SARS viri cause the exact same illnesses,
virus infection in the lungs, bacterial lung infection by the immunosystem
overreaction plus a cykotine storm (T-cells running amok), it's commonly
called the flu.

The virii don't do any damage, the immunosystem is doing the damage.

2nd, the speed of the infection is irrelevant for herd immunity, only the
concentration. In some cases 30% is enough, in most cases 70%. The higher the
R, the higher the needed percentage. In our case with a natural R of 3.5 80%
is needed.

~~~
ceejayoz
"Flu-like symptoms" and "the flu" are not the same thing. COVID-19 is not the
flu (and it's substantially more fatal than what we term "the flu", as well).
SARS-CoV-2 causes a number of symptoms not typically seen in flu, as well; it
is not "the exact same illnesses".

> The virii don't do any damage...

This simply isn't true (and would be a pedantic quibble if it were, akin to
describing getting shot as "acute lead poisoning").
[https://en.wikipedia.org/wiki/Lytic_cycle](https://en.wikipedia.org/wiki/Lytic_cycle)

> 2nd, the speed of the infection is irrelevant for herd immunity, only the
> concentration.

Faster spreading viruses tend to have higher R values as a result.

