
Aerosol and surface stability of HCoV-19 compared to SARS-CoV-1 [pdf] - mhb
https://www.medrxiv.org/content/10.1101/2020.03.09.20033217v1
======
aaronscott
From the paper: "Our results indicate that aerosol and fomite transmission of
HCoV-19 is plausible, as the virus can remain viable in aerosols for multiple
hours and on surfaces up to days."

This partially explains how quickly this virus spreads, and why such
incredible measures are required to stop the spread.

~~~
nostromo
> and why such incredible measures are required to stop the spread.

Since we're learning that the fatality rate is much lower than SARS, as was
feared early on, and that it's much more mild of an illness -- and also that
it's highly contagious and already widespread -- it strikes me that the
opposite is true.

We should do everything we can to protect the elderly and ill, but a disease
that is so mild that 85% of people over 80 still survive it, it doesn't strike
me as something worth tanking the global economy over. If you're middle-aged
or younger and you drive to work, travel internationally, drink alcohol, etc.,
you've taken similar risks as COVID-19 poses to you.

This is incredibly unpopular on HN, and I'm ok with that. Holing everyone up
in their apartments for the next year would put almost everyone reading this
out of a job, many without housing, and without healthcare. This is a "keep
calm, wash your hands, and carry on" moment, and we're failing.

~~~
ardit33
There are reports, that plenty of those "80%" mild cases have pneumonia and
permanent lung scaring (aka, you will never be able to play intense sports),
even though they don't end up in a tube/forced oxygenation....

Sorry, I'd rather take a 2 months economy hit, than a long term burn.... which
will cause a longer term economic problem as well.

~~~
nostromo
The decision isn't to either get it now or not at all. The decision if you'd
like to get it now or later.

If you decide to get it now, you probably have a job. If you decide to get it
later, you quite possibly don't.

~~~
marcinzm
And if everyone gets it now the health system collapses, 15% of the infected
die and anyone who needs a hospital for any life-saving reason also dies.

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logjammin
Thanks for posting this. As someone in public health research, I really
appreciate being able to get as close as possible to empirical findings about
corona. It helps me deal both rationally and emotionally with the crisis.
Obviously "it's just a preprint", but this is great to have -- leagues better
than a watered-down and panicked-up version from cross-eyed cable news hosts.

I've found that the major scientific and biomedical research journals - the
BMJ, the Lancet, the NEJM, JAMA, Science, Nature - collectively have some of
the best stuff on coronavirus out there. It's not as fast as the news, but
it's a hell of a lot more rigorous.

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davidw
I wonder what - if anything - post offices / delivery services are doing about
this stuff? A lot of people hunkered down at home are going to use those to
order things.

~~~
devit
People should not handle any package for at least 3 days after reception
assuming this paper is correct (unless they manually disinfect it).

EDIT: actually the paper doesn't seem to conclude that 3 days is enough, and
instead than an unknown number of days, but at least 3, is required, at least
relative to their detection method

~~~
erichurkman
Can you effectively disinfect porous materials like paper and cardboard?

~~~
Gibbon1
Spray disinfectant on it. Expose to bright sunlight. Cook it at 70 deg C.

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pteiavn
"In short, aerosols (<5 μ m) containing HCoV-19 (105.25 69 TCID50/mL) or SARS-
CoV-1 (106.75-7 TCID50/mL) were generated using a 3-jet Collison nebulizer and
fed into a Goldberg drum to create an aerosolized environment. Aerosols were
maintained in the Goldberg drum and samples were collected at 0, 30, 60, 120
and 180 minutes post-aerosolization on a 47mm gelatin filter (Sartorius).
Filters were dissolved in 10 mL of DMEM containing 10% FBS. Three replicate
experiments were performed."

I looked up "Goldberg drum" and found this
[https://www.researchgate.net/figure/Aerosol-
apparatus-A-40-L...](https://www.researchgate.net/figure/Aerosol-
apparatus-A-40-L-Goldberg-drum-used-for-aerosol-survival-studies-inside-
the_fig3_231212356) which looks pretty small. It would dissipate a lot more in
a room, and even more outdoors. How can we account for the effects of
dissipation?

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abruzzi
The slightly tangential question I had was, OK, a potential active lifespan of
2-3 hours in aerosol form, but in a normal environment, how long is it likely
to remain in aerosol form before settling on a surface, and in what
environments is it likely to remain airborne for 2-3 hours?

~~~
logjammin
That's a good question, no doubt. A related one I had was (and maybe I missed
this), but what's the "dose" of virus one needs to get infected? In the
discussion of decay / half life of the virus on surfaces and in the air, I
wondered about this. It's one thing if the virus can hang around for three
hours and infect you at any time, and another thing if it's in the air for
three hours but decays at ____ rate and can only infect for 1 hour.

~~~
Amarok
TCID50 gives you information on infectivity. Not as good as LD50 though
[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4861875/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4861875/)

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csytan
From the paper:

> Virus stability in aerosols was determined as described previously at 65%
> relative humidity (RH) and 21-23°C. In short, aerosols (<5 µm) containing
> HCoV-19 (105.25 TCID50/mL) or SARS-CoV-1 (106.75-7 TCID50/mL) were generated
> using a 3-jet Collison nebulizer and fed into a Goldberg drum to create an
> aerosolized environment. Aerosols were maintained in the Goldberg drum and
> samples were collected at 0, 30, 60, 120 and 180 minutes post-aerosolization
> on a 47mm gelatin filter (Sartorius). Filters were dissolved in 10 mL of
> DMEM containing 10% FBS. Three replicate experiments were performed.

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RichardHeart
COVID19 lives for 3 hours in air. 2-3 days on stainless steel and plastic.
Only 4 hours on copper, which is why all door handles should be copper! Other
anti-viral and bacterial materials are available as well.

~~~
heretoo
or everyone should wear copper gloves

~~~
GuB-42
Or gloves filled with mercury...

Obviously, that's a joke but it is probably not as bad as you might think.
Liquid elemental mercury is relatively harmless. Compare to mercury vapor,
which is bad, and organic mercury, which is worse than bad.

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RichardHeart
Here's how well copper as a surface kills viruses and bacteria:
[https://en.wikipedia.org/wiki/Antimicrobial_properties_of_co...](https://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper)

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ardit33
So, someone sick goes into an elevator/bus/small places, they cough, and get
on. The guy coming 5 mins later, having no clue, might get infected....

And while 'wash your hand', helps some, it is mostly just a way to make people
feel control, as that seems not to be the main vector of transmission. This
explain how quickly many people get it.....

This is a crude analogy, but: if you are close enough to someone and you would
probably noticed if they 'farted', then there is a good chance that you would
get some potential covid-19 particles if their coughed it out.....

~~~
GuB-42
Don't forget the "viable on surfaces up to days" part.

Someone coughs on a doorknob, _hours_ later, you touch the doorknob, virus
goes on your hand, you touch your face, you get infected.

Even if you don't touch your face, your dirty hands spread the virus
everywhere, including on food and to other people.

And even if touch isn't the main vector, it is better than nothing. Remember
that the goal is to make the rate of transmissions less than 1, so if washing
hands help us go down from 1.1 to 0.9, even if isn't that much of a
difference, it is all we need to beat the virus.

