
The science of mask-wearing hasn’t changed, so why have our expectations? - hooloovoo_zoo
https://fivethirtyeight.com/features/the-science-of-mask-wearing-hasnt-changed-so-why-have-our-expectations/
======
davesque
What confuses me is why so much scrutiny is being placed on the practice of
wearing a mask. It just hardly seems like much of an inconvenience. And common
sense dictates pretty convincingly that it must have _some_ benefit, however
small. So then why so much effort into deciding if it works or not?

I suppose there are two answers to that question. One, health officials want
to know if masks give a false sense of security so they can spend their time
promoting measures that will actually make a difference. Two, folks just want
a reason to avoid the minor inconvenience or, worse, have been led to believe
that mask mandates seriously impinge upon their rights. My concern is that the
most common answer is the second and articles like this only serve to confuse
people at a time when we need to accept that we must make small sacrifices to
solve this problem.

~~~
Wowfunhappy
> It just hardly seems like much of an inconvenience.

Not arguing that any of this is a good enough reason to not wear a mask right
now, but, I find them pretty darn inconvenient.

It's very uncomfortable. It fogs up my glasses when I’m inside, and covers up
a large part of my field of view even when I’m outside. I can't ride my
scooter at all because with that field of view loss, I'm worried I'll crash
into something. Talking is more difficult, both projecting enough to be heard
through the mask and straining to hear others.

I've tried several different masks at this point, so I don't think that's it.

~~~
DoofusOfDeath
When I'm doing construction, I often wear a form-fitting N95 mask (for dust
protection) and safety glasses.

The top of the mask, and the nose-bridge of the safety glasses, compete for
the same location on the bridge of my nose.

If I layer them so that the mask touches my skin, and the eye glasses rest on
the mask, I have no problem with fogging.

If I layer them the other way: the eye glasses' bridge directly on my skin,
and the top of the mask resting on the eye glasses' bridge, I get fog.

Maybe you're experiencing this?

I usually avoid this simply by putting my eye glasses on after my mask is in
place.

~~~
Larrikin
It's almost completely dependent on the masks construction. I never had
problems with my n95 from 3m, but the kn95 I have is impossible to wear with
glasses no matter how I fit it.

The surgical mask a friend got for me in March looks near identical to the
pack of masks I got recently besides the color but the one she got me fogs up
my glasses while the pack I have now never does.

~~~
DoofusOfDeath
FWIW, the mask I was referring to in the GP is the GVS SPR457 Elipse P100 [0].

(As a side note, I haven't tried many masks, but I find this one extremely
comfortable and effective.)

[0]
[https://www.amazon.com/gp/product/B013SIIBFQ/ref=ppx_yo_dt_b...](https://www.amazon.com/gp/product/B013SIIBFQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1)

------
corny
From an outsider perspective (I'm Canadian), the politicalization of wearing a
mask seems like a huge distraction from action that can make a much bigger
difference:

* staying home when even a little bit sick

* physical distancing (esp. indoors)

* hand washing

* don't touch your eyes, nose, mouth with unclean hands

* getting tested if having symptoms

* if physical distancing is not possible, then wearing a mask (esp. indoors)

I kind of worry that in a desperate attempt to improve the economy, US
governments will continue to ignore the advice of experts and embrace mask-
wearing as a panacea.

~~~
SpicyLemonZest
US governments have to deal with the fundamental problem that the US public
doesn't want to physically distance anymore. They want to gather with friends
and family, eat in restaurants, drink in bars, even hold large public
gatherings for their political causes. If the government doesn't offer advice
on how to do these things safely, that'll just mean they get done unsafely.

~~~
closeparen
Was it ever the plan to maintain physical distancing for the next several
years? As lockdowns started, the most alarming projections had us cycling it
on and off periodically. Not going cold turkey on all human interaction for
the long haul.

~~~
dragonwriter
> As lockdowns started, the most alarming projections had us cycling it on and
> off periodically. Not going cold turkey on all human interaction for the
> long haul.

The projected initial period of lockdown before going into cycling was longer
than even the places that locked down early and reopened late had it, and that
was assuming coordinated national response not many places not initially
participating in the lockdown.

------
woodandsteel
This article has some interesting points, but overall it is click-bait.

The recommendation at the end is, “We don’t know how well cloth masks work, so
distancing should come first, but masks are likely to work to some extent and
not everyone can distance themselves.” But for most of the article it talks as
if the whole matter is so uncertain no recommendation can be made.

Anyway, the whole idea that we should wait until the science is all settled
before we make policy decisions is quite impractical. We are learning as we
are fighting the epidemic, and so we have to make decisions before we have
full evidence. Indeed, the only way we can learn if masks work to help stop
the epidemic is to have some countries mandate them and compare the results
with countries that don't. Epidemics are very different than individual
diseases. You have to make decisions at the group level, and when it is a new
disease you have to do so without really good understanding.

And we know that the countries that have pursued a whole set of rigorous
policies that includes face masks have been successful, while countries that
are lax, include face masks, have failed. So the smart thing to do is pursue
the set of policies that includes face masks, and later on find analyse the
data and find out exactly how important they are.

------
stri8ed
I would like to see more discussion around, if the initial viral load is
related to the severity of the infection[1].

If yes, then in theory, a mask could provide large benefits, even in absence
of a perfect seal around the face.

[1] [https://www.lesswrong.com/posts/3ArEA7tHDXQxE6PED/taking-
ini...](https://www.lesswrong.com/posts/3ArEA7tHDXQxE6PED/taking-initial-
viral-load-seriously)

~~~
credit_guy
Absolutely.

The initial disinformation campaign by the western governments (and the CDC
and the WHO) that masks are useless for their wearer (due to the shortage of
masks, and the fear they won't be enough for the health care personnel) has
long lasting effects.

That was an abject lie, and people have paid with their life for that.

The governments now don't know exactly how to turn around and communicate that
yes, masks are useful, we've been lying to you all this time, sorry for that,
now you can go ahead and wear some.

You can't do an 180 like that, can you? So for now it's "masks are good for
the others, but they won't help you. but don't you want to be a good team
player?".

~~~
nefitty
What is stopping individuals from holding a nuanced understanding of politics
similar to this comment?

~~~
JMTQp8lwXL
Indoctrination to their social circle (family, friends, etc). You'll become an
outsider by expressing opposing opinions.

------
hassancf
This is a good read “The Masks Masquerade” by Nassim Taleb of Black Swan fame:

“First error: missing the compounding effect” ... “Third Error: Mistaking
Absence of Evidence for Evidence of Absence” ...

[https://medium.com/incerto/the-masks-
masquerade-7de897b517b7](https://medium.com/incerto/the-masks-
masquerade-7de897b517b7)

~~~
justnotworthit
I liked his point that if you believe in "cause no harm" (non-agression), you
should wear the mask. It raises issues in what counts as real harm/aggression
(wearing clothes someone in society dislikes is technically "harm", but not a
harm considered real or aggressive or... I forget the terms).

Then he insults everyone who disagrees with him multiple names and accusations
of bad faith (which makes serious discussion undesirable and difficult). I
think that's a thing Taleb does (online).

------
SonnyTark
Here in NZ, masks were never required. The rationale is that when people wear
masks no matter how you explain it they believe they themselves are safe,
which makes them get closer to other people (I can't give them the disease)
and be less cautious in general (I'm protected). Take the mask away and the
only things they have is social distancing and being obsessive about touching
surfaces. Which in my experience works very well and it's what the community
here focused on.

In the meantime my folks in Maine wear masks and gloves and think now
everything is fine we can do anything and go anywhere.

------
giardini
As timer notes in another post below, the episode _" Special Episode: Masks
and Science"_

talks about the history of masks vis-a-vis Covid-19:

[https://www.cidrap.umn.edu/covid-19/podcasts-
webinars/specia...](https://www.cidrap.umn.edu/covid-19/podcasts-
webinars/special-ep-masks)

 _In this episode, Dr. Osterholm and host Chris Dall discuss the current
science on COVID-19 and cloth masks._

Transcript available at

[https://www.cidrap.umn.edu/revised-mask-
transcript-6220](https://www.cidrap.umn.edu/revised-mask-transcript-6220)

------
wdr1
I wear a mask. I encourage all my friends to wear a mask. It's a very low
cost, with large potential upside. There's no good reason _not_ to wear a
mask.

But I am also interested in the pure science & am asking strictly from that
point of view. Again, I am __not __suggesting we don 't need to wear masks.

I found this report on the CDC website that states:

"Although mechanistic studies support the potential effect of hand hygiene or
face masks, evidence from 14 randomized controlled trials of these measures
_did not support a substantial effect on transmission of laboratory-confirmed
influenza_ "

(emphasis mine)

[https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article](https://wwwnc.cdc.gov/eid/article/26/5/19-0994_article)

I'm aware it's for influenza & not COVID-19, but most research, including
evidence suggesting we should wear masks, is based on research done on
influenza. I think it's reasonable, given the paucity of COVID-19 data and we
have to do something, and given they're both RNA viruses, experts feel it's
reasonable as well.

My conclusion from above is that while we should still definitely wears masks,
it's unlikely wearing them will see a noticeable change in R0, which is what
we need to really open up. I.e., opening with mask compliance probably isn't
going to work, and we need people to stay home.

I'm not an expert, so would to love to learn if I've got anything wrong.
Thanks in advance.

------
jakeogh
The virus is in the same class as some common colds. It's not "going away". If
people are concerned about it they should use a real mask designed to filter
viruses[1]. Instead, the population is being conditioned to force medical
procedures on other people. Forever.

The "flatten the curve" thing was predictably re-goalposted.

There are strong financial incentives to keep people irrationally in a state
of fear. After this, there will be the next.

This keeps getting ignored: What is the non-COVID-19 pneumonia # for
2019-2020?

CDC Influenza and pneumonia deaths by influenza season and age: United States,
2008–2015: [https://www.cdc.gov/nchs/data/health_policy/influenza-and-
pn...](https://www.cdc.gov/nchs/data/health_policy/influenza-and-pneumonia-
deaths-2008-2015.pdf) (these are not estimates, see the footnote)

    
    
      CDC #'s 2015-2016
      Flu: 7,961
      Pneumonia: 131,858 
      All: 1,769,940
    

[1]
[https://news.ycombinator.com/item?id=22232633](https://news.ycombinator.com/item?id=22232633)

~~~
corny
> If people are concerned about it

Until more is learned about covid-19 people should be concerned. Where the
disease is out of control, hospitals are filling up and many people in need of
health care are suffering as a result.

BTW, at least in Canada, the number of deaths due to covid-19 has been
concentrated most in long-term care homes. These are also places where deaths
due to pneumonia and flu are common. We're learning now that the quality of
care in these homes has been insufficient to deal with covid-19. All of the
measures that are now in the works to improve the quality of care in those
homes should have the side-effect of reducing deaths from other infectious
diseases in the future.

~~~
jakeogh
The excess death stats are accessible to us all. What's the non-COVID-19
pneumonia # for 2019-2020 so far?

It's nonsensical to expect everyone to agree, those that want a mask, should
use one for viruses. This is like pretending the cold is going away, and we
must all obey until that happens. Wont happen.

As you mention, fixing the situation of the vulnerable is the way. Quite
possibly would have been better response in the first place.

Viruses are only getting easier to engineer. Shutting down the country only
makes them _more_ valuable.

------
pabe
"Martin worried that wearing masks might lead people to feel more safe than
they actually were — and make choices that increased their risk of contracting
or transmitting COVID-19." \- I don't see people wearing masks jumping into my
face. It's people who're feeling safe for other reasons, that do. People who
don't see there's a pandemic. People who think it's all made up. People who
feel invincible or who're thinking they can show-off as invincible to impress
others. Those people don't wear masks and throw one Corona Party after
another. I'd assume that most people wearing a mask care more deeply about
others than those who don't. So, wearing a mask is also a statement. And it's
got almost nothing to do with politics.

------
xtiansimon
> “... a public health and disease expert who is worried that mask
> effectiveness is being over-hyped...”

Medical professionals have their own sources of information (just talk to a
doctor about hand washing vs. hand sanitizer).

Then I assume the concern is some members of the public are taking risks while
wearing masks, thinking they are more safe than they really are? I don’t
understand the concern, because if you’re really concerned about the virus
you’re staying home. If you’re cavalier about the whole thing, then you’re
likely standing <6feet and doing other “risky things”. And finally, for
everyone else there are the simple rules.

This seems totally different than, say, the controversy about the anti-
malarial drug, which had severe potential side effects.

What am I missing?

------
prox
So what is needed to get to that certainty? What research is being done or
must be done?

~~~
cmiles74
Should we even bother, now that masks are becoming easier to purchase?

~~~
lolc
Given that we're heavily inconvenienced by the masks and other measures, we
should find out how well they work so we can focus on the stuff that helps the
most.

------
trhway
The CDC best estimate is that US has 20M+ covid cases right now (
[https://www.nbcbayarea.com/news/coronavirus/cdc-says-
covid-1...](https://www.nbcbayarea.com/news/coronavirus/cdc-says-
covid-19-cases-in-us-may-be-10-times-higher-than-reported/2315636/)) . That
number has beem reached with all the masks wearing and lockdowns.

So, what is the difference between the expectations in case of mask wearing
vs. not wearing by the end of the year? Even with masks wearing and lockdowns
we're probably talking about high tens of millions or even 100M for US. Can it
be higher without masks and lockdowns? Spanish flu infected just under one
third of total population. For covid, New York had probably reached about 2M
cases (~20% of population) and the infection rate went down after that. Using
that model of 20% (and NY has much higher population density) it means 70M
infections for the whole US. Given how we've already reached 20M+, i think
that number will be reached no matter what in a few months (give or take a bit
depending on masks, lockdowns, etc.), well before wide availability of
vaccine.

So, it is really not about whether masks work, it is about whether it makes
any noticeable difference in the current situation. I personally was for total
population mask wearing, temp checking, etc. back then in Dec/Jan/Feb because
back then we had a chance to stop the spread. These days i just don't see any
arithmetically consistent way to avoid the described above scenario and stop
the current flooding/tsunami.

~~~
adjkant
You assume here that NYC's numbers went down via some property of the disease,
not a lockdown being observed by the whole city along with high mask usage.
Letting this "run its course" would spike NYC and the whole US far above 70M
cases. We would easily be looking at 500,000 dead at least even with how we've
learned to decrease the death rate. That death rate would also go up as we
stop flattening the curve, as we saw happen quickly with Texas.

NYC has had decreasing numbers despite large outdoor protests, which had high
mask usage. In a week or two there will be some numbers on how Phase II
reopening is going in an area with high mask usage as well which should be
another good data point.

Here are some actual interesting scenario tools for controlling the virus even
as it runs its course:
[https://ncase.me/covid-19/](https://ncase.me/covid-19/)

As a note, a big factor here is that it appears that antibodies may only last
for 2-3 months which breaks some of those recovery models. If that is true,
without any mitigation and even with most at-risk people dying off earlier, we
could still end up losing .1% - 1% of the population every 3 months until we
have a treatment or vaccine. I don't like how those numbers look even if we
manage to get a vaccine in 12 months.

~~~
trhway
>some property of the disease

it seems that only some share of people is susceptible to a given virus like
covid, flu, etc. (for whatever reason, like some genetic characteristic or for
example presence of antibodies from some other virus which happen to help
here). Say for example half of the population, 50 out of 100. So once 20
people got it, there are 30 left to be infected while all the others - 70 -
can't participate in the infection spread, and 70% is pretty close to herd
immunity.

Add to that the estimates that herd immunity for covid can be even less than
half [https://www.usnews.com/news/health-
news/articles/2020-07-02/...](https://www.usnews.com/news/health-
news/articles/2020-07-02/could-threshold-for-covid-19-herd-immunity-be-lower-
than-thought) \- that would explain the infection rate drop in NYC.

~~~
adjkant
> Say for example half of the population, 50 out of 100.

I think you're confusing susceptible and immune. If the antibody numbers are
legit, then the asymptomatic rate is around 90%, but that's not the full
story. You have to remember that asymptomatic people still spread the virus,
so this plays differently in herd immunity modeling. You're still looking at a
1% average death rate in NYC too given those numbers.

That 50% of people you mentioned is not about symptomatic - they must also not
be able to transmit. Otherwise using a SIR model or similar there's still 80%
of the population that can catch and infect others. I have seen nothing about
such natural immunity in people even in small numbers, let alone at 50% of the
population. That assumption is doing a lot of legwork in your herd immunity
claim.

At best, your assumptions still means we need to accept just under a million
deaths. At worst, even with no increased death rate due to hospital load,
that's closer to 3 million. When other countries have shown clear alternatives
by taking measures that don't lead to 1% of their population dying (such as
Germany at 0.01% so far), one of which is mask usage, I don't see how there's
harm in the policy when it could mean literally saving millions of lives.

All of that relies on antibodies lasting, which doesn't seem to be
guaranteed[1], as I pointed out in my post before. That can make this much
worse if/when people begin to catch it again.

[1][https://www.cidrap.umn.edu/news-
perspective/2020/06/chinese-...](https://www.cidrap.umn.edu/news-
perspective/2020/06/chinese-study-antibodies-covid-19-patients-fade-quickly)

~~~
trhway
NYC made masks law on April 15. Germany somewhere around a week later.

> I don't see how there's harm in the policy when it could mean literally
> saving millions of lives.

there is no harm. I wear my. Even though all the facts and math shows that it
doesn't make any noticeable difference at this point.

>At best, your assumptions still means we need to accept just under a million
deaths

accept or no accept, covid doesn't care. Anyway, we have already "accepted" it
by letting it develop into the current scale. I think original Fauci deaths
estimates - up to 250K - made under obvious political pressure to voice lower
numbers than he'd do otherwise - is pretty close. From the current 20M+ we'd
get 3-4x with death rate falling, thus we'd get into 250K-500K range. I don't
see how masks or lockdowns, which haven't been able to stop us from the 10000x
jump - tens/hundreds cases into tens of millions - are going to stop us from
the 3-4x or even 10x (if the 10x were possible in the current situation which
it isn't because the herd immunity threshold looks to be significantly lower)

~~~
adjkant
> NYC made masks law on April 15. Germany somewhere around a week later.

And you left off that NYC's cases dropped the entire time those mask policies
were in effect. We didn't isolate for it as the lockdown was in place, but
there's at the very least a positive correlation, and the lack of spike from
the protests supports that too. I don't see why you jump to defeatism from
that evidence.

You're assuming people in most of the US paid attention to the laws and
advisories. In Florida for example, mask usage was incredibly low and has
caused the spike there. Same for Texas. We don't know if masks would stop the
initial jump because we didn't use them. All evidence from other countries
points to the conclusion that they do help in a meaningful way.

If you're saying you don't believe the American populace is capable of
following instructions, you might be right, but if we actually enforced and
practiced mask policies, it very much appears it would make a meaningful
difference.

~~~
trhway
>And you left off that NYC's cases dropped the entire time those mask policies
were in effect.

you're right. I somehow was under impression that the peak cases were a month
later there. Lets see. I'm still really not optimistic giving the current
scale of the spread.

------
nateberkopec
It's been really interesting to watch this pandemic from Japan, where I've
been for the last ~3 months. I am an American citizen.

Walking around Tokyo this week I'm still seeing mask rates of >95%. Lockdown
ended about 2 weeks ago.

In America, mask-wearing carries a different set of social signals. It seems
that not wearing a mask is perceived, by some, as a signal of one's virility
and freedom.

The article makes this all pretty clear, but the comments here are getting
bogged down in "but the data says masks are/aren't effective". The point is
that the data doesn't matter. Mask-wearing is determined by social/political
expectations and signaling, not by data.

If a study came out tomorrow that said mask-wearing reduces transmission by
95%, Trump still wouldn't wear one. Looking for a silver bullet study to prove
a point either way is a waste of time at this juncture.

Apparently, asking Americans to show that they care about the health of
another American via a very low-impact signal (the $10 it costs to get/make a
mask, the minor inconvenience of wearing one) is too much.

How can a society solve any size of a problem when it cannot be bothered to
put a piece of paper or cloth on their face for the possible benefit of
another? If your political climate makes such a minor gesture controversial,
how will you solve any meaningful issue where your factions disagree?

How do you get Americans to care about the health and welfare of other
Americans?

~~~
HeyZuess
> Walking around Tokyo this week I'm still seeing mask rates of >95%. Lockdown
> ended about 2 weeks ago.

I currently live in Asia and have been for many years, I am from a western
country. I think in Asia, face masks are just a fact of life, including pre-
covid. There is/was an expectation that if you are sick, then you should
probably wear a mask. Given that a lot of cities are crowded, many wear masks
also not to get sick.

As a westerner, I understand the negative connotations of wearing a mask, it
is not a part of "normal life" in many countries. But life has changed, people
should get used to it. Americans should just look at the stats to know that
there is a problem. This isn't an attack on their freedoms, it is an attempt
not to save their life, but the life of a fellow American, by preventing the
spread.

While China may have been the epicenter of the virus, the spread is the
responsibility of the citizens of the secondary country.

------
TACIXAT
This seems like it is casting uncertainty when there is really good evidence
that wearing masks is effective.

[https://www.theguardian.com/commentisfree/2020/apr/04/why-
we...](https://www.theguardian.com/commentisfree/2020/apr/04/why-wear-a-mask-
may-be-our-best-weapon-to-stop-coronavirus)

~~~
timr
On the contrary, there's actually very little evidence that masks are
effective for the general public. Particularly for cloth masks, the evidence
is essentially non-existent. You're citing an article by Jeremy Howard, who is
quoted in the OP, and whose opinion is directly rebutted.

Michael Osterholm of CIDRAP has written a rather scathing summary of the data
for cloth masks, and the political and social machinations that have gotten us
where we are. He calls out Jeremy Howard as a particularly vocal spreader of
scientific misinformation on the topic:

[https://www.cidrap.umn.edu/covid-19/podcasts-
webinars/specia...](https://www.cidrap.umn.edu/covid-19/podcasts-
webinars/special-ep-masks)

(edit: how can you possibly downvote a link to a factual source that is _cited
in the article_? Consider your bias.)

~~~
cmiles74
In my opinion, it's unreasonable to expect that there would be studies on the
effects of cloth masks. Up until the quarantine began the reasonable
assumption was that if you needed a mask you wore the one appropriate to your
task. I don't think cloth masks were in widespread use until these masks
became scarce.

Maybe some studies are happening now. Even so, it probably makes more sense to
encourage people to purchase more reliable masks.

~~~
timr
_" In my opinion, it's unreasonable to expect that there would be studies on
the effects of cloth masks."_

That's fine, but there are lots of plausible interventions that have little/no
evidence, and we don't mandate those by law. Why this one?

For example, the Lancet study commissioned by the WHO found that _eye
protection_ is about as supported by the available literature as surgical
masks. Why aren't we all required to wear goggles?

I believe that "science" should not be used to mandate actions that have no
scientific data backing them.

 _" it probably makes more sense to encourage people to purchase more reliable
masks."_

The issue there is still shortages. I don't buy surgical or n95 masks, because
other people need them more than I do.

~~~
ceejayoz
> For example, the Lancet study commissioned by the WHO found that eye
> protection is about as supported by the available literature as surgical
> masks. Why aren't we all required to wear goggles?

Because masks are being recommended to work on _outgoing_ virus. Unless you've
evidence respiratory viruses spread significantly via jets of air emitted via
your eyeballs, this is a weird argument.

~~~
timr
_" because masks are being recommended to work on outgoing virus. Unless
you've evidence respiratory viruses spread significantly via jets of air
emitted via your eyeballs, this is a weird argument."_

If you read the Lancet paper, you'll find that they pooled papers for source
control and PPE together to arrive at their conclusions. In fact, _most_ of
the papers they used in that meta-analysis were for surgical masks used as PPE
(personal protective equipment) in a medical setting.

In other words, the advocates for masking are doing the same thing that you're
saying is weird. If you try to break the analysis down according to specific
lines of evidence (i.e. source control for the public), you quickly find that
there's not enough data to draw any conclusion.

On the other hand, the argument _in favor_ of this kind of pooling is
straightforward: if your end goal is to reduce transmission of a virus, and
you find that goggles are highly effective at _preventing infection_ , then it
doesn't matter very much. Tell everyone to wear goggles instead, and forget
about the masks. Transmission will still be reduced.

~~~
ceejayoz
Medical settings are concerned largely with PPE that protects the staff, and a
number of healthcare procedures are aerosol-generating.

Mask wearing for COVID is targeted at reducing likelihood of spreading to
someone else.

> If you try to break the analysis down according to specific lines of
> evidence (i.e. source control for the public), you quickly find that there's
> not enough data to draw any conclusion.

We're going to get a lot of data soon, but for the time being, it's probably
best to err on the side of "something that stops droplets probably helps stop
a disease spread by droplets".

~~~
DanBC
We already have lots of data. Here's the Lancet paper:
[https://www.thelancet.com/journals/lancet/article/PIIS0140-6...](https://www.thelancet.com/journals/lancet/article/PIIS0140-6736\(20\)31142-9/fulltext)

> Our search identified 172 observational studies across 16 countries and six
> continents, with no randomised controlled trials and 44 relevant comparative
> studies in health-care and non-health-care settings (n=25 697 patients).
> Transmission of viruses was lower with physical distancing of 1 m or more,
> compared with a distance of less than 1 m (n=10 736, pooled adjusted odds
> ratio [aOR] 0·18, 95% CI 0·09 to 0·38; risk difference [RD] −10·2%, 95% CI
> −11·5 to −7·5; moderate certainty); protection was increased as distance was
> lengthened (change in relative risk [RR] 2·02 per m; pinteraction=0·041;
> moderate certainty). Face mask use could result in a large reduction in risk
> of infection (n=2647; aOR 0·15, 95% CI 0·07 to 0·34, RD −14·3%, −15·9 to
> −10·7; low certainty), with stronger associations with N95 or similar
> respirators compared with disposable surgical masks or similar (eg, reusable
> 12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%,
> low certainty). Eye protection also was associated with less infection
> (n=3713; aOR 0·22, 95% CI 0·12 to 0·39, RD −10·6%, 95% CI −12·5 to −7·7; low
> certainty). Unadjusted studies and subgroup and sensitivity analyses showed
> similar findings.

The important bit here (for everyone saying we have great evidence that masks
work) is that "low certainty" bit. That's GRADE, and it means "low certainty
(our confidence in the effect estimate is limited; the true effect could be
substantially different from the estimate of the effect);" So, maybe masks are
substantially less, or more, protective.

~~~
ceejayoz
Like I said, I'm not doing the dance again.

Last time it was pointed out "low certainty" doesn't mean what you imply it
does
([https://news.ycombinator.com/item?id=23434344](https://news.ycombinator.com/item?id=23434344))
you let it sail on by.

~~~
DanBC
Here's what low certainty grade results mean: "low certainty (our confidence
in the effect estimate is limited; the true effect could be substantially
different from the estimate of the effect);".

Just so we're clear: you've never linked to research to support any of your
points, because you're not able to, are you?

~~~
ceejayoz
> Just so we're clear: you've never linked to research to support any of your
> points, because you're not able to, are you?

I did. 28 days ago.

[https://news.ycombinator.com/item?id=23434255](https://news.ycombinator.com/item?id=23434255)

[https://news.ycombinator.com/item?id=23434053](https://news.ycombinator.com/item?id=23434053)

> Here's what low certainty grade results mean: "low certainty (our confidence
> in the effect estimate is limited; the true effect could be substantially
> different from the estimate of the effect);".

You're acting like its definition is "it's probably the opposite, and thus is
evidence for my argument".

~~~
DanBC
And last time you posted those links I pointed out that they were for the same
paper and the paper doesn't support your point.

Here's someone explaining what GRADE means:

[https://twitter.com/dnunan79/status/1269014574478626819](https://twitter.com/dnunan79/status/1269014574478626819)

"I teach GRADE

If something has “low quality” evidence, it means the observed estimate is
highly likely to be different from the truth.

Face masks = low quality evidence.

So what’s the point of GRADE if we can conclude “evidence shows”?"

EDIT: Your link even says this

> Further high-quality research, including randomised trials of the optimum
> physical distance and the effectiveness of different types of masks in the
> general population and for health-care workers' protection, is urgently
> needed

------
ljlolel
[https://medium.com/p/4ef05aa357c5?source=linkShare-72308c464...](https://medium.com/p/4ef05aa357c5?source=linkShare-72308c464041-1586107578)

------
johndoe42377
The "science" of mask wearing is plagued by redundant and irrelevant abstract
mathematical concepts.

A mask is a membrane (not perfect, of course) and this is how it must be
properly modelled.

It is that simple - just use proper (right) abstractions.

All the sophisticated statistical extrapolations is just flawed bullshit.

------
arminiusreturns
I just want to point out all the people who say "It's about protecting others,
not yourself" or some variation _are part of the problem_! That can be said
about the random diy cloth masks, but for everything else:

The science of masks hasn't changed...

N95 – Filters at least 95% of airborne particles. Not resistant to oil.

Surgical N95 – A NIOSH-approved N95 respirator that has also been cleared by
the Food and Drug Administration (FDA) as a surgical mask.

N99 – Filters at least 99% of airborne particles. Not resistant to oil.

N100 – Filters at least 99.97% of airborne particles. Not resistant to oil.

R95 – Filters at least 95% of airborne particles. Somewhat resistant to oil.

P95 – Filters at least 95% of airborne particles. Strongly resistant to oil.

P99 – Filters at least 99% of airborne particles. Strongly resistant to oil.

P100 – Filters at least 99.97% of airborne particles. Strongly resistant to
oil.

I've been wearing a p100 respirator that makes a good seal to protect myself,
and been changing out a small piece of cloth on the out-valve to protect
others. Please, stop perpetuating the myth that masks don't protect you. Of
note is that while many of the higher rated masks tend to be tested at .3
microns, this is often a buffer and real world they tend to filter about .1...
and the virus is said to be .12+ micron.

So if you can, I would suggest getting your hands on n100 or p100, preferable
use an oximeter to make sure you have the physical fitness needed to force the
air through, but if you are doing very small timeframe adventures this becomes
less of an issue. Something that makes a good seal is ideal. Guys, you should
heavily consider shaving. There is a reason in the military NBC training they
started requiring with only a few exceptions, shaves... and no, the military
gas masks will not work for this application unless you get the specific
filters for this application (if you do, they would be great since they
integrate the eyepro), which have a much wider ranger to select from than the
above I reference...

note: it is also very important to verify you haven't been sold a fake product

[https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part...](https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/default.html)

~~~
thoraway3030
I think that the whole "masks don't protect you they protect others" spiel was
designed to save face, because authorities were adamant about masks not
working until March. Of course they protect the wearer....otherwise healthcare
workers wouldn't use them.

~~~
grahamburger
I'm pretty sure health care workers wear them primarily to protect others.
This is what my health care worker friends have told me (long before covid).
Sneezing on someone mid surgery would be pretty bad for the patient, not
really for the surgeon.

I think the reason people say it's more for others than yourself is because
it's actual pretty rare to catch a disease by breathing it in. Much more often
you catch it when it gets on your fingers and then you touch your
eyes/nose/mouth. I think that's still at least partially true with covid.

