
Respiratory virus shedding in exhaled breath and efficacy of face masks - haltingproblem
https://www.nature.com/articles/s41591-020-0843-2
======
calibas
Why is virus transmission via aerosol such a controversial thing? When you
cough, microscopic water drops get suspend in the air and studies have proven
other strains of coronavirus can survive in these particles, especially in
office conditions.

[https://www.ncbi.nlm.nih.gov/pubmed/32226116](https://www.ncbi.nlm.nih.gov/pubmed/32226116)

And there's at least one study that found healthcare workers are at higher
risk of infection during medical procedures that create aerosols.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338532/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3338532/)

Perhaps it's some human bias and we dread the idea that simply sharing the
same atmosphere puts us at risk?

This could be something very positive actually, and lead to rapid non-invasive
testing. Imagine virus testing as part of the air filters on planes and cruise
ships, could be a very powerful tool for preventing outbreaks.

~~~
ceejayoz
In the infectious disease world, droplets and aerosol aren't the same thing.

[https://www.statnews.com/2020/03/16/coronavirus-can-
become-a...](https://www.statnews.com/2020/03/16/coronavirus-can-become-
aerosol-doesnt-mean-doomed/)

> The reason the measles is so, well, viral, is that the microbe is so small
> and hardy that it is able to stay suspended in the air where an infected
> person coughed or sneezed for up to two hours, making it one of the only
> viruses that can exist as a true aerosol.

> Now there are conflicting reports on whether the new coronavirus can. The
> studies suggesting that it can be aerosolized are only preliminary, and
> other research contradicts it, finding no aerosolized coronavirus particles
> in the hospital rooms of Covid-19 patients.

~~~
amiga_500
When I read measles has an R0 of 18 that just blew my mind.

That thing just spreads like wildfire.

~~~
fermienrico
Now imagine a virus in future with R0 of 18, incubation (while contagious) of
14 days and a CFR of 50%. This would wipe out entire populations of humans.

~~~
amiga_500
Agreed, this is why after this, whatever the root cause, we should have
international "discouragement" on disease research. This stuff is going to
leak out. Not saying this one did.

~~~
ceejayoz
Been in place since the 1970s.

[https://en.wikipedia.org/wiki/Biological_Weapons_Convention](https://en.wikipedia.org/wiki/Biological_Weapons_Convention)

------
ravenstine
This is why people need to learn to listen to their intuition and their common
sense instead of losing out to the tyranny of the experts during critical
situations.

I don't care if the experts don't want a run on masks. Anyone of modest
intelligence knows that paper with little holes in it impedes the movement of
air and droplets. Even if a mask is poorly sealed, surely it does _something_
for both the infected and the uninfected, yet we've allowed the authorities,
the experts, to gaslight us into accepting that the sky is blue so that they
could augment their supply with masks intended to be sold to civilians. Under
normal circumstances, individuals can afford to wait for evidence and listen
to it. Now there are people who are going to die because they trusted the idea
that they shouldn't wear a harmless piece of paper.

If they didn't want a run on masks, they should have chosen to say something
other than an insult to our intelligence, and then backtrack. And if you don't
believe that the CDC, WHO, journalism outlets, were begging people to not wear
masks back in February, I have to wonder what rock you've been living under.

~~~
ceejayoz
There are lots of places where common sense and intuition fail us. Experts are
important. The issue here is they tried a hamfisted approach of _lying_ to
prevent panic buying.

What _should_ have happened was "masks work, here's an approved pattern you
can make at home with just some cloth, and we're nationalizing PPE production
and distribution for the time being; please know that's so the healthcare
workers who may save your lives can stay alive".

~~~
ravenstine
Exactly. There's no denying that. And that's the public statement that we all
_deserved_. But we're all too used to accepting misinformation from the
authorities because we trust that they know better and that the ends will
justify the means, which is a highly dangerous mindset because it damages our
ability and willingness to distinguish reality of fantasy. In the worst case,
it means that we'll accept anything.

~~~
ceejayoz
The issue is "common sense and intuition" is what gets us anti-vaxxers,
climate change denial, etc. As the saying goes, common sense isn't common.

I'd like to see steps taken to increase the independence of organizations like
the CDC from the political world.

~~~
ravenstine
> The issue is "common sense and intuition" is what gets us anti-vaxxers,
> climate change denial, etc. As the saying goes, common sense isn't common.

I'm sorry, but yes it is.

First off, those are not common-sense issues. They're complex, and just
because they make sense to the high IQ crowd on HN doesn't meant that they
have any reflection on common sense. Just because anti-vaxxers say that
vaccines are bad because "common sense" doesn't mean that it has anything to
do with other than them being morons.

Common sense is that masks do something and aren't harmful to use. Common
sense was right. Just because common sense and intuition are sometimes wrong
doesn't mean that they're always wrong, which would be a fallacy. It doesn't
even take common sense; an average joe can use basic cost-benefit analysis to
decide whether to use a mask, if they are wondering whether a mask is a good
idea. Trusting people(often pundits) with ulterior motives over a month after
the fact would have turned out to be less advantageous.

This idea that we can't ever use our intuition because it's often wrong is
dangerous. If we can't make any decision with intuition, including one as
harmless as wearing a piece of paper over our faces, then we're slaves of the
mind.

~~~
ceejayoz
"Mercury is a deadly poison. It is common sense that having it in a vaccine is
bad."

This makes perfect, intuitive, common sense to a significant portion of the
population.

~~~
wavepruner
"...to a significant portion of the population."

Including health experts:

"...depending on the vaccine formulations used and the weight of the infant,
some infants could have been exposed to cumulative levels of mercury during
the first six months of life that exceeded EPA recommended guidelines for safe
intake of methylmercury. As a precautionary measure, the Public Health Service
(including FDA, National Institutes of Health [NIH], Centers for Disease
Control and Prevention [CDC] and Health Resources and Services Administration
[HRSA]) and the American Academy of Pediatrics issued a Joint Statement,
urging vaccine manufacturers to reduce or eliminate thimerosal in vaccines as
soon as possible. The U.S. Public Health Service agencies have collaborated
with various investigators to initiate further studies to better understand
any possible health effects from exposure to thimerosal in vaccines."

[https://www.fda.gov/vaccines-blood-
biologics/vaccines/thimer...](https://www.fda.gov/vaccines-blood-
biologics/vaccines/thimerosal-vaccines-questions-and-answers)

To this day thimerosal is not included in childhood vaccines, except for some
flu shot formulations.

~~~
ceejayoz
> Data reviewed did not demonstrate convincing evidence of toxicity from doses
> of thimerosal used in vaccines. In case reports of accidental high-dose
> exposures in humans to thimerosal or ethyl mercury toxicity was demonstrated
> only at exposures that were 100 or 1000 times that found in vaccines.

~~~
wavepruner
They could just as easily say, "Data reviewed did not demonstrate convincing
evidence of safety from doses of thimerosal used in vaccines."

Placebo-controlled, double-blind clinical trials have never been completed to
evaluate the safety of thimerosal. Partly because it would be unethical to
inject a known toxin into people to determine it's safety.

If these trials had been done, and health authorities were convinced it was
safe, they would allow thimerosal in vaccines because it is a huge cost saver.
But instead, through the actions they took, they made it clear it is not worth
the risk.

As an environmental engineer I've witnessed this tactic over and over.
Authorities claim there is no evidence of danger, but remove the toxin
anyways, because they know it's danger is plausible, and the funding and time
isn't there to prove it one way or the other. Absence of evidence is not
evidence of absence.

It's not like they are going to say, "we think we may have poisoned people, so
we're removing this toxin." That's a great way to destroy your livelihood,
reputation, and invite prosecution.

~~~
ceejayoz
> Placebo-controlled, double-blind clinical trials have never been completed
> to evaluate the safety of thimerosal. Partly because it would be unethical
> to inject a known toxin into people to determine it's safety.

The safety of thimerosal is entirely possible to evaluate. It was in a bunch
of childhood vaccines; it now is not. Has there been any demonstrable
difference?

> But instead, through the actions they took, they made it clear it is not
> worth the risk.

Not necessarily. Could just not be worth the fight with the anti-vaxxers
spreading bullshit about it. See also: Subway ditching azodicarbonamide
because some blogger started a scaremongering movement around it.

~~~
wavepruner
"The safety of thimerosal is entirely possible to evaluate. It was in a bunch
of childhood vaccines; it now is not. Has there been any demonstrable
difference?"

If you don't believe that proper clinical trials are important to evaluate
safety then there's not much more I can say. Epidemiological studies are rife
with problems and the data can be manipulated to claim almost anything you
want.

"Not necessarily. Could just not be worth the fight with the anti-vaxxers
spreading bullshit about it. See also: Subway ditching azodicarbonamide
because some blogger started a scaremongering movement around it."

Good point, but mercury is one of the most toxic substances known to man, does
not break down, and is scientifically proven to bio-accumulate in mammalian
tissues and never leave. It was also injected directly into the body,
bypassing all the normal biological defenses a compound must go through before
entering tissues. Furthermore, people can chose to not eat Subway without
consequence. If vaccines had thimerosal in them again, it would be unavoidable
without major life changes and being forcibly removed from large swaths of
civil society. A consequence so severe necessitates a more proof than just
saying you think mercury is safe in small doses with zero supporting concrete
evidence.

Thimerosal was removed around 2001, well before the anti-vaxxer movement had
enough influence to matter.

Your feelings and weak suppositions about thimerosal in vaccines are not
science, and rather just indicate that you want to believe what you want to
believe without presenting any concrete evidence.

------
exhilaration
This video was posted on /r/Coronavirus/ and was pretty interesting:

Micro droplets suspending in air
[https://vimeo.com/402577241](https://vimeo.com/402577241)

------
ceejayoz
Another nail in the coffin for the "masks don't work" side of things.

~~~
nisa
nobody said masks don't work - the article doesn't contradict the fact that
masks don't protect you very good against other infected people next to you.
This article just repeats that it's known that masks help to prevent spreading
of the disease if you have symptions and need to go outside. At least here in
Germany nobody ever spoke out against that.

~~~
vinniejames
WHO said masks don't work

~~~
AlexandrB
Here's what the WHO site[1] says:

• If you are healthy, you only need to wear a mask if you are taking care of a
person with suspected 2019-nCoV infection.

• Wear a mask if you are coughing or sneezing.

• Masks are effective only when used in combination with frequent hand-
cleaning with alcohol-based hand rub or soap and water.

• If you wear a mask, then you must know how to use it and dispose of it
properly.

Nowhere do I see: "Masks don't work".

[1] [https://www.who.int/emergencies/diseases/novel-
coronavirus-2...](https://www.who.int/emergencies/diseases/novel-
coronavirus-2019/advice-for-public/when-and-how-to-use-masks)

~~~
dnissley
I think the first point is what most people are talking about when they're
saying the WHO said "masks don't work".

"Masks don't work" being short hand for "masks will only help you in these
very narrowly defined circumstances."

~~~
Mirioron
Even the third point is likely to discourage people from using masks. I find
it difficult to believe that people with a mask, even if used poorly, see
absolutely no benefit from the mask. The mask's presence on your face should
already make you less likely to touch your face. Furthermore, the novel
coronavirus is not the only thing to worry about. All of the other illnesses
are still abound and will likely make you more susceptible to the novel
coronavirus.

------
chkaloon
Just to be clear, they are talking about surgical-type masks, similar to the
cloth masks people are making.

They are NOT talking about N95 "masks". There is constant confusion in the
press and elsewhere between these two.

One protects others (surgical mask), and one protects others AND the wearer
(N95).

Vox proposed that we call N95s by their technical term, "respirators", and
other masks "masks", but then I suppose people will start confusing
"respirators" and "ventilators"

~~~
0xffff2
I don't know that I entirely buy this. Okay, the masked I sewed myself out of
an old shirt and some coffee filters isn't nearly as effective as an N95 mask,
but is it really 0% effective? Surely it's better than nothing?

~~~
chkaloon
Boy you're quite the contrarian. Congratulations. Did I say 0% effective?
Talking about primary use here. You're right, though, that cloth or coffee
filter is better than nothing.

~~~
0xffff2
>One protects others (surgical mask), and one protects others AND the wearer
(N95).

Maybe you didn't mean it that way, but that sure sounds pretty absolute to me.

~~~
chkaloon
From OSHA
[https://www.youtube.com/watch?v=ovSLAuY8ib8](https://www.youtube.com/watch?v=ovSLAuY8ib8)

------
beeforpork
One thing in this study I find totally surprising is this: how can aerosol
from different virus classes be differently contagious when passing through a
mask? They seemed to have measured that, but it would really be very
interesting to get an explanation how this is possible. How does a mask filter
the contagion from corona aerosol, but not from rhino aerosol. This is totally
perplexing to me.

~~~
ceejayoz
[https://en.wikipedia.org/wiki/Rhinovirus](https://en.wikipedia.org/wiki/Rhinovirus)

> They are lytic in nature and are among the smallest viruses, with diameters
> of about 30 nanometers. By comparison, other viruses, such as smallpox and
> vaccinia, are around ten times larger at about 300 nanometers; while flu
> viruses are around 80–120 nm.

The smaller the virus, the easier it slips through a mask's fibers.

------
chucklenorris
something that i don't fully understand - as a healthy person does wearing a
mask has any effect? or the masks work only for reducing the chance of
transmitting the virus if already infected?

~~~
dlandis
> something that i don't fully understand - as a healthy person does wearing a
> mask has any effect?

Yes, of course it has an effect. Why do you think health care workers wear
them?

~~~
Angostura
"Yes, of course it has an effect. Why do you think health care workers wear
them?"

Because they will be closer than 6ft to infected people.

~~~
ceejayoz
So, if they work at less than six feet, they probably work _at_ six feet or
greater too, right?

