[throwaway_pdp09]

I've read repeatedly (and heard on the radio several times) that wearing a mask if YOU are infected will help protect other people, but if you are not infected then it has no known protective effect ie. is not thought to be any more protective than not wearing one.

Do you have any evidence to back up you talk of masks?

(And if YOU are infected you should not be out anyway)

Edit: I was thinking of non-medical situations. @j7ake below, clearly pointed out they work in medical situations, something I was not contesting at all but did not make clear. The original post talked of "wearing masks in public" which was clearly not in medical situations and I was following through that.

[cyphar]

This was a coordinated (dare I say "propaganda") campaign by US and other government officials in order to try to avoid mask shortages[1]. A noble goal, sure -- but the net result is that people are now misinformed about the efficacy of masks.

The evidence very much shows that wearing masks can reduce community transmission rates of SARS-like viruses -- up to 70% even with just plain surgical masks[2]. And even if you don't buy that, everyone wearing a mask means that asymptomatic carriers (who have no idea they're sick) cannot spread it as effectively.

[1]: https://www.nytimes.com/2020/03/17/opinion/coronavirus-face-... [2]: https://medium.com/@adrien.burch/whats-the-evidence-on-face-...

[h91wka]

> This was a coordinated (dare I say "propaganda") campaign by US and other government officials in order to try to avoid mask shortages[1]. A noble goal, sure -- but the net result is that people are now misinformed about the efficacy of masks.

There's nothing noble about it. This is extremely short-sighted. What is easier to solve, shortage of masks, or shortage of ICU beds and medical personnel?

I would imagine that a face mask is a relatively low-tech good that can be mass-produced at scale. You cannot ramp up production of ICU beds and nurses and doctors. If this is true, then the consequences of this "noble" decision will make Chernobyl blush.

[cyphar]

Avoiding mask shortages is a noble goal (note that you're agreeing with me here -- mass-producing masks would also have avoided shortages). Whether or not the method employed was ethical or not is a separate question (and I agree with you that it was not because of how short-sighted it was).

[h91wka]

> note that you're agreeing with me here

I am not. My point is that solving the problem of mask shortage by allowing the infection to spread at full speed is like setting your home on fire to deal with a clogged pipe.

[catalogia]

To say that somebody had a "noble goal" is to state that their intentions were good, not malicious. That is not the same as being correct. You are pointing out that they were shortsighted fools who did more damage than good, which I agree with, but that's not incompatible with having good intentions.

The road to hell is paved with good intentions.

[KarlKemp]

Scott Alexander has a good post on this, and he convinced me of a “good faith” explanation for the recommendations against (or, more accurately, “not in favor of”) face masks: https://slatestarcodex.com/2020/03/23/face-masks-much-more-t...

[nullc]

His explanation does not explain statements like https://twitter.com/Surgeon_General/status/12337257852839321...

[cyphar]

I hadn't seen that post before, and it does seem quite reasonable -- but I don't think it really vindicates the advice (nee propaganda) from government officials, unless there was no other way to alleviate shortages. The conclusion is effectively "we don't know for sure, but they do appear to help somewhat" -- which means that (all other things being equal) not recommending masks appears to be a net negative.

[throwaway_pdp09]

Finally someone posted something factual. Thanks! Reading now.

[nopinsight]

You do NOT know if you are infected. Asymptomatic carriers is a major problem for COVID-19. A figure I saw was about 50% of infections come from them.

Here's evidence and list of 34 science papers backing up the utility of masks in slowing down a viral epidemic:

Thread with charts, articles, link to paper summaries: https://twitter.com/jeremyphoward/status/1242894378441506816

ADDED: Just the list of papers & their brief summaries: https://docs.google.com/document/d/1HLrm0pqBN_5bdyysOeoOBX4p...

[throwaway_pdp09]

Could you post the list here for us who can't use twitter (permanently disabled JS).

[llarsson]

Then your browser does a shitty job of telling Twitter that. Properly blocked JS gives you a link to "legacy" Twitter, which works perfectly without JS. At least viewing, which is all I do.

Does this link work for you?

https://mobile.twitter.com/jeremyphoward/status/124289437844...

[throwaway_pdp09]

I've never been able to use it. I get sent to a "do you want to use legacy twitter?" thing, I click Yes and it just gives me the same screen again, every time.

Happens I proxy through squid - it might have something to do with that. If I go direct (no proxy) it works. Interesting.

At least I can get to it, and will read your link this evening. Thank you.

[llarsson]

Until I started blocking JS using uBlock Origin, my blocking must have been incomplete. Because I also saw that screen and it never worked. Now, it does.

[j7ake]

This advice is completely contrary to anything that happens inside a hospital. Nurses and doctors are wearing surgical masks (and N95 masks plus face shield if performing actions that may generate aerosols) to protect themselves from getting sick while treating patients.

The problem is that you can have COVID19 and be contagious without showing symptoms. Mandating everybody to wear some sort of mask should reduce transmissions because it should reduce the viral load in the air. By how much? It is not clear, but it's not worth waiting for results from a randomized double blind clinical trial during a global pandemic. I would put money that the effect of putting on a mask will be at least as effective as washing hands.

The danger to be careful of is if wearing mask can make you more sick, but the current actions from healthcare workers around the world suggests it is not the case.

Another point some people argue is that wearing a mask in public means one less mask for health care workers. This is false on two fronts, one because mask supplies will soon flood the market and there are DIY solutions to masks that can reduce transmissibility; two because what's best for health care workers is not to get sick at all.

[foobarian]

I am hopeful that the US public may warm up to masks in public in the future. It seems likely this would cut down on the spread of seasonal flu and common colds.

[raaaaraaaa12]

Yes that's right even your own DIY face mask protect other people. And that's enough to slow down spreading...

You dont know for first ~5-6 days whether you are infected or not.

https://www.businessinsider.com/people-are-making-diy-face-m...

Don't worry too much about effectiveness of DIY face masks - in few months Respilon and other Czech companies will put on market face masks made from nanomaterials which filters virus much more effectively ;)

[throwaway_pdp09]

Valid rebuttal, thanks.

OK, I think that the mask over your own face is to prevent viral spread in largish water particles caused by coughs and sneezes, not general breathing (I'm not sure general breathing spreads much virus anyway, but I don't know).

So if you are infected and not showing symptoms ie. not coughing/sneezing then arguably the mask is not doing anything.

Arguably not, but we need more data - can anyone comment with sources?

[mcsb4]

> So if you are infected and not showing symptoms ie. not coughing/sneezing then arguably the mask is not doing anything.

It prevents you from touching your mouth and your nose and thus getting it on your hands.

There is an excellent video visualising the spreading of germs:

https://www.youtube.com/watch?v=I5-dI74zxPg

How To See Germs Spread (Coronavirus) by Marc Tober

Maybe that convinces you.

[raaaaraaaa12]

Even if you are breathing calmly mask will catch some small water droplets so spreading is somehow contained. It's true that after ~1 hour wowen mask will become wet and no longer effective. But it's not problem wear some other masks in your bag and change it... Currently there's huge shortage of respiratory protection products globally so your old wowen tshirt will help you :)

[Lewton]

> not coughing/sneezing then arguably the mask is not doing anything.

People cough and sneeze all the time even if they're not sick.....

[haunter]

> wearing a mask if YOU are infected will help protect other people

How do I know I'm not infected? There are a lot of asymptomatic carriers, that's the main problem.

A lot of people still think that no symptomps = not infected = no mask needed but that's totally wrong

[mantas]

Wearing mask discourages you from touching your face with your hands.

If someone sneezes at you, even most simple mask will stop at least 50% of viruses. If someone was far away and only a small load reached you, that may be enough to keep you safe.

> (And if YOU are infected you should not be out anyway)

The big problem is to know when you're infected. Mask keeps others safe if you're not aware that you're infected.

Some reports say that you start distributing viruses pretty much immediately after getting it yourself. Even if all contacts (which is far from guaranteed) get traced and you get checked and/or isolated in a day or two, you'd be already spreading viruses for that timeframe.

[throwaway_pdp09]

> Wearing mask discourages you from touching your face with your hands

Good point!

> If someone sneezes at you, even most simple mask will stop at least 50% of viruses

sounds plausible, but any reference for that figure?

[mantas]

That's what is posted in our local media. I'm not sure if it comes from local gov agencies or WHO or something else.

FFP2 / N95 respirators - 90-something percent, medical "blue" masks - 80 percent, home-made piece-of-cloth style ~ 50%.

Wearing sunglasses is encouraged too. Both to stop the load if someone sneezes at you and discourage from touching your eyes.

[brutt]

N95 - 95% at least.

Medical mask - 96,4%.

Home made mask - 60-96% (depends on cloth and sewing).

https://www.researchgate.net/publication/258525804_Testing_t...

[mantas]

Maybe you and I have different medical masks in mind? I was talking about masks like this:

https://cdn.shopify.com/s/files/1/0080/6830/0851/products/6_...

https://www.123rf.com/photo_138981777_stock-vector-person-we...

https://phonetub.com/products/100-disposable-face-surgical-m...

The main problem with blue masks and home made is that they tend to get wet from breath and their effectiveness go down the drain.

[endorphone]

"no known protective effect"

Right. No one has ever studied contagions among the community at large and the effect of masks. When you hear people say there is no evidence, this is what they are referring.

"is not thought to be any more protective than not wearing one"

This is taking that claim too far, and is seldom what they're saying. Or rather never what they are saying.

Early on there were PDAs that discouraged masks because a) there is a weird social effect in much of the West where people get panicky, and somehow view someone else wearing a mask as increasing the odds, or at least the reality, that they instead will get sick, b) to discourage personal buyers competing with medical buyers, c) because the odds of coming into contact with a SARS-CoV-2 carrier was very low, whereas it's high to very high for medical professionals.

We need to discard with that bullshit. We know with overwhelming evidence that masks work -- that's why medical professionals wear them -- and even the lowly surgical mask has the same effectiveness blocking pathogens in as they do out, especially aerosol pathogens like this one.

And of course we know that people can be spreading this without symptoms, so it would be a massive win just for that.

As supplies normalize and manufacturers ramp up, we're quickly going to be at a place where most in the West will be wearing a mask of some fashion, and it will be officially encouraged. This whole weird anti-mask paranoia will have cost lives.

Masks aren't a panacea, of course, They should be properly worn and rotated. Add that they increase the effort the lungs have to exert, especially N95 masks, so in a unfortunate irony people with compromised lungs -- the most vulnerable to COVID-19 -- have the most difficulty using masks.

[throwaway743]

>a) there is a weird social effect in much of the West where people get panicky, and somehow view someone else wearing a mask as increasing the odds, or at least the reality, that they instead will get sick

Definitely experienced the stigma of wearing one in public. Have had reactions ranging from stares to hurriedly moving away from me.

> We need to discard with that bullshit. We know with overwhelming evidence that masks work

To add, why else would NY ask older folks to wear masks when going outside?

Also, this NIH study adds to support that masks are effective.

https://news.ycombinator.com/item?id=22485453

[endorphone]

"Definitely experienced the stigma of wearing one in public"

People can be deeply illogical when it comes to personal protection. I did a summer stint during college with a factory, assembling some part of an air conditioner system for cars. This was done with huge, incredibly loud machines. Fiberglass. Etc.

The company offered ear plugs, eye protection and masks. No one used them. There was a 0% utilization rate. It was bizarre. I did, however, and earned snarky comments, critical suggestions, and lots of sideways glances. People really seemed to feel that my concern for myself made the threats more real.

I'd like to say that when I left everyone had followed the path I blazed, but it was the same as it always was. People still sabotaged their own health and hearing to avoid looking "paranoid".

[magduf]

Where was this?

I used to work as an intern at a shipbuilding company making aircraft carriers. People wore stuff when they were required to, so hard hats were always worn, and the attached earmuffs seemed to be generally worn when someone was working with something very loud.

However, at one point I was helping an inspection in a tank and there was a noxious odor, and I couldn't breathe in it. The shipyard worker with me went ahead and went in and did the test, but after this I tried to procure a respirator and they refused to get me one, saying it wasn't necessary for the work I was doing.

Music concerts are another place where you don't see people using personal protection much, though I will say that's changed in the last 10 years from what I've seen. I do see a minority (but a growing one) of people wearing earplugs, and we now have a lot of choices for "musician's earplugs" being sold which are designed to have a neutral frequency attenuation.

[throwaway_pdp09]

A quick scan and search does not use the word 'mask' or 'protection' anywhere I can see.

> why else would NY ask older folks to wear masks when going outside?

I don't know. Is there any evidence that significant proportion of experts are recommending this practice, and why BECAUSE THAT'S WHAT I'M ASKING FOR.

[nullc]

> Right. No one has ever studied contagions among the community at large and the effect of masks.

It's been studied. There has not been a randomized controlled trial because performing one would be extremely unethical.

There is plenty of study evidence to support their use, just nothing meeting the gold standard of a RCT and there never will be one against a true live fire contagious disease.

The irony with all this is that the US administration really want to get people back to work as soon as possible. Massive deployment and mandatory usage would be the safest way to do that the soonest.

Too bad they already foreclosed that option by materially misleading the public.

[cyphar]

> Right. No one has ever studied contagions among the community at large and the effect of masks. When you hear people say there is no evidence, this is what they are referring.

Actually, they have[1,2]. According to one study, surgical masks helped cut down the community spread of SARS in Beijing by 70%[3]:

> Always wearing a mask when going out was associated with a 70% reduction in risk compared with never wearing a mask.

But if you're specifically referring to randomised trials on mask efficacy during an on-going pandemic, you're right that there are no such studies -- because it would be unethical. So effectively all of the relevant studies are retrospective (which does introduce recall bias), but these are basically the best studies we can do ethically.

[1]: https://medium.com/better-humans/whats-the-evidence-on-face-... [2]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993921/ [3]: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3322931/

[throwaway_pdp09]

> that's why medical professionals wear them

Of course we know it works for them, because in your own words "coming into contact with a SARS-CoV-2 carrier was low, whereas it's high for medical professionals"

> We know with overwhelming evidence that masks work

Yes they do, for medical professionals. I'm referring to non-medical situations, and I guess I didn't make that clear. I'm trying to understand why... well, I explained in my first post. I'm not looking for opinions but for actual solid evidence. Which someone (not you) actually provided.

[endorphone]

We don't work for you. Your various snotty replies aren't useful.

"Of course we know it works for them"

How does this anti-logic make any sense? Do you think the masks have a sensor that turns off the "works" bit if it's on the face of a medical professional or not?

This is bit like demanding to see research that gravity has an impact on alpacas. We know fundamentally how gravity has an effect on mass, so it follows. Just as we know the fundamental filtering ability, and contagion spread limiting, of masks, including even surgical masks. We know that the CDC is telling health workers that don't have masks to even use a bandana wrap, as not only does it stop face contact it has some limited utility in stopping the tiny droplets of liquid that are one of SARS-CoV-2's vectors.

[mcsb4]

Many people don't know they are infected and also there is not enough testing capability in many countries. For example Heidi Klum tired to get tested after catching a cold and it took her several days to be accepted for a test. Now she is not exactly your average Joe and would be willing to shell out a few 1000 dollars to get tested.

Unless that situation changes, masks are a good alternative. And yes, only if everybody wears them.

[mikemotherwell]

Let's assume healthy people do not need a mask. In fact, let's take it as Gospel, and the statement "Healthy people have no use for a mask" as absolutely true.

Given we know there are people with COVID-19 who are asymptomatic, any "Healthy people have no use for a mask" can simultaneously be true, and be practically irrelevant, as any definition of "healthy people" is necessarily impossible to prove. You simply can not know you are free of Corona Virus, short of having recovered from the virus.

If the standard was EVERYONE wears a mask, asymptomatic people would be a non-issue. Any advice contrary to the 100% mask usage argument has to explain how we deal with asymptomatic people. Short of testing everyone all the time, what would that even be?

TL;DR In a world with asymptomatic COVID-19 people, a 100% mask policy seems the sane default position.

[throwaway_pdp09]

Then WHY ARE SO MANY EXPERTS TELLING US WHAT I QUOTED?

What you say (and others too) makes sense to me and I could well believe it true, but I'm NOT claiming that masks are useless unless you are infected, I'M ASKING IF ANYBODY KNOWS WHY EXPERTS ARE SAYING OTHERWISE (or whether I just heard an unluckily skewed sample)

Plus, I also asked for a citation to back up the poster's position, not common-sense arguments (which are a good starting point but not evidence in themselves).

[j7ake]

Which experts are saying masks are not effective? From what I read the experts (curiously from countries that did not prepare enough masks for their hospitals) say it is not recommended for the general public to wear a mask. They definitely still recommend nurses, doctors, and sick people to wear one. But they never explicitly say that masks do not reduce transmission. They may have said "there is little evidence to suggest..." which is not the same as masks do not reduce transmission.

The official position for many countries that are containing the virus suggests wearing a mask when out in public. One notable exception is Singapore.

Here is the Korean society of infection FAQ that says wearing a mask can reduce transmission:

https://translate.google.com/translate?sl=ko&tl=en&u=http%3A...

[throwaway_pdp09]

Thanks, I've updated my original post.

[mikemotherwell]

Masks may be 100% irrelevant for healthy people, but we have asymptomatic people. There is no way to ascertain who is healthy, ergo "healthy people don't need masks" is practically redundant. What am I missing?

Oh, and you want citations, sorry, my bad:

https://docs.google.com/document/d/1HLrm0pqBN_5bdyysOeoOBX4p... - 30 some citations on masks.

[throwaway_pdp09]

> What am I missing?

See my reply https://news.ycombinator.com/item?id=22701821 Mind, I just don't know if what I'm saying there holds water.

Citations are good, following up!

[SuoDuanDao]

I imagine to prevent mask shortages and to make law enforcement easier.

[RedBeetDeadpool]

So I was in agreement with this, and the science is that yes it only helps in containing the infection if the person infected is wearing the mask.

However, if healthy people aren't wearing the masks, and only the unhealthy are, then the unhealthy don't want to signal they are unhealthy so they don't either. A huge part of getting the infected to wear masks is to get the healthy to wear masks so the infected don't put a huge label on themselves that indicates: "diseased", "corrupted", "infectious", "frail", "unclean" etc.

Logic says one thing, but people are not logical like machines.

[Lewton]

Seriously. How is it possible to still be ignorant about the (up to) 2 week asymptomatic incubation period? This is the entire reason why the virus is so dangerous!

And where did OP mention anything about masks protecting the carrier from infection?

[throwaway_pdp09]

See my other reply. Plus I said "And if YOU are infected you should not be out anyway"

[ceejayoz]

> Plus I said "And if YOU are infected you should not be out anyway"

The point you're missing there is that some people are asymptomatic. They don't know they're infected.

[throwaway743]

https://news.ycombinator.com/item?id=22485453

[nikbackm]

You might not know that you are infected.