
Asymptomatic transmission, Achilles’ heel of current strategies to control Covid - megamike
https://www.nejm.org/doi/full/10.1056/NEJMe2009758?query=RP
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oski
This is why everyone should wear a homemade face mask when they are out in
public near other people.

~~~
nostromo
If you’ll permit a tangent:

Don't wear masks in your car alone. Or outside alone. Or outside or in your
car with people you live with.

Not only does it not do any good, it actually increases your exposure to any
pathogens your mask acquired while in public.

Take your mask off when you're not around other people you don't live with.
And take it off appropriately (not touching the mouth or nose area with your
hands).

Another stupid thing you shouldn't do: wear a mask in public only to
repeatedly pull it off to speak.

~~~
interestica
> If everyone will permit a rant:

> Don't wear masks in your car alone. Or outside alone. Or outside or in your
> car with people you live with.

That's not useful. Outside alone and then put on if someone approaches? How
does wearing it in your car alone increase exposure?

If you've been outside, you want to reduce the amount of times you're touching
and putting on/taking off the mask as those are the moments when you're
increasingly possibility of transmission (getting on hands, other surfaces).
If I see someone wearing it in the car, I'm assuming it's the best practice:
reducing the on/off instances.

~~~
nostromo
> How does wearing it in your car alone increase exposure?

Because any pathogens you were exposed to in public are behind held up against
your mouth for an extended period of time.

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kyawzazaw
the point of the public masks is to limit the wearer spreading droplets.

~~~
sharken
I could swear that most people use them to protect themselves, always look out
for number 1.

In Asian countries this might be different though.

~~~
amalcon
They might think they're wearing them for that reason, and I'll certainly take
it. That said, it's not terribly effective for that purpose..

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chris_va
This is not wrong, but maybe fairly obvious, and why the unwinding strategies
require contract tracing to test for pre-symptomatic infection.

The article asserts that additional testing capacity is required for
prophylactic testing, but that statement is both true and false. We will
probably need ~20x testing capacity for just contact tracing to get R0<1\. At
that point, prophylactic testing (say every 3-5 days) of health/elderly care
workers would be a marginal increase.

~~~
zamfi
> R0<1

A nit: you can’t change R0 without changing the virus — it’s the reproduction
constant _without intervention_.

We want to get R < 1!

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spockz
I see many posts referring to this virus being contagious during while being
asymptotic but infected. Is there any other proper source of this? Our
government/health agency is denying asymptotic transmission happens.

~~~
anon9001
Here's a good starting point:
[https://www.npr.org/sections/goatsandsoda/2020/04/13/8318835...](https://www.npr.org/sections/goatsandsoda/2020/04/13/831883560/can-
a-coronavirus-patient-who-isnt-showing-symptoms-infect-others)

May I ask which country?

If the CDC, WHO, and PhD's of Public Health are all saying the same thing,
it's probably true.

~~~
cycomanic
I assume Sweden, the public health agency here has been denying asymptomatic
spread, at the same time they wonder how the virus got into the retirement
homes which have been hit very hard. They say something along the lines of "we
have to find out who didnt follow the guidelines" However they don't consider
the obvious, maybe it spread via asymptomatic carriers

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jonny_eh
I think anyone paying attention knows this already?

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bobbydroptables
It should have been, but strangely even public health officials were very
recently advocating strongly against masks unless you had symptoms. No one has
ever able to explain to me why symptoms were relevant in any way given that
many or most carriers are asymptomatic.

Even the WHO continues to advise against wearing masks for "healthy" people
(i.e., presumed asymptomatic carriers).

~~~
macintux
To me, completely untrained in medicine, their guidance seems much more
nuanced than you suggest.

[https://apps.who.int/iris/rest/bitstreams/1274280/retrieve](https://apps.who.int/iris/rest/bitstreams/1274280/retrieve)
(pdf)

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ggrrhh_ta
That's at least the fourth version, look for the archived recommendations in
January, February and March, the April one is the first one to touch upon all
the aspects directly and more honestly.

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macintux
Ok, but the key word in the parent was “still”. That pdf dates back to early
April.

(Sorry, “continues”.)

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myrryr
Stay at home as much as you can beats any amount of masks.

Go look at how New Zealand has done.

~~~
SpicyLemonZest
But you understand that New Zealanders aren't going to stay at home for the
rest of their lives, yes? So they'll still need an answer to the question of
how to safely resume going out.

