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Comment by TACIXAT | Hacker News Reader

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...

It's effective but it sounds like the fear is that the effectiveness is overhyped (says this specifically in the article)... and I think that's a valid concern.

If everyone thinks they can go out wearing a mask and forget about distancing and other measures, then that complicates things. Wearing a mask to go grocery shopping for 20 minutes is also different than say, wearing a mask and sitting in a theater or bar for 2 hours.

Also, well fitted N95 style masks are very different from a loose mask around the face.

Still makes a world of difference though, especially because your mask (unless N95) isn’t for you as much as it’s for others. If two people interacting are both wearing - even loose fitting - cloth masks over their nose and mouth, the chance of spreading disease is orders of magnitude less.

We do not actually know that. That is the point.

People are talking elsewhere in the thread about glasses fogging up. That, even with an extremely non-airtight mask, that is reused, touched constantly, etc. seems like prima facie evidence to me that it deflects the stream of droplet-laden air from your face, thus inhibiting it from spraying on to others.

Like others have said, if this were a different disease, maybe it would be spread more by contact and masks wouldn't be worth bothering.

And if you're only focused on how a mask can protect you, maybe it doesn't help that much. But if you are infected without knowing it...

Edit: my pun was unintentional...really, I swear.

But we literally do. Do a cursory google search. Hell even Pence wears one.

We actually DO know that

Well, then where is the scientific evidence that simple masks reduce chance of spread by an order of magnitude, as described?

There is none, because the science hasn't been done. There's a viral JPEG on the internet that claims this, it's just that.

If we don't have that evidence, the we don't really know, plain and simple.

That's not to say people should stop wearing masks. It's plausible that they help. It's just that we don't know the extent to which they help.

Widespread Use of Face Masks Could Save Tens of Thousands of Lives - https://www.npr.org/2020/07/03/886905055/widespread-use-of-f...

That's a projection based on assumptions on the efficacy of masks. The point is that we don't have a number for that efficacy. We just don't know.

Masks have always been controversial, but I think what we have seen in terms of outcomes in the NY/NJ/CT area shows that they likely have some effect.

Usually the studies that knock masks compare them against people following good hand washing protocol. Mask vs. person with good hygiene is different than the typical slob you find on the street.

The actual fear should be from people who dont wear masks, dont wash hands and generally act like covid-19 is a hoax.

It does not even matter whether the non-mask wearer is not wearing it because he believes mask is not effective, mask is not needed due to covid not existing or mask is sign of being fearful and one gotta project bravery.

Mask wearer who skipped washing hands once or approached someone 1.5 meters is still good.

"The actual fear should be from people who don't wear masks"

I don't understand this. The actual fear should be any form of scientific misinformation. Eventually, the truth will be known, and if "scientists" are deemed to be advocating for policies that aren't supported by science, it will hurt science in the long run.

On top of this, there is decent reason to believe that there's a down-side to mask laws: too many people think that they can behave normally if they're wearing a mask, when the evidence simply doesn't support it.

>On top of this, there is decent reason to believe that there's a down-side to mask laws: too many people think that they can behave normally if they're wearing a mask, when the evidence simply doesn't support it.

I have seen this repeated many times but have not seen any evidence that really supports it. It just sounds like a common behavior. I would imagine the cross-section of people who are already going to act like it wasn’t a big deal and people who wear a mask that act like it’s not a big deal is already substantial. And while I also don’t have any data, I think it is as common sense as the other assumption and thus illustrates my point.

Anecdotally, people give you a fair bit more space when you’re wearing a mask and clearly taking precautions than if you aren’t. I’d argue that in the current political climate, mask wearing might actually improve distancing measures. The people who aren’t wearing masks just don’t seem to give a shit. It’s a social signal about if you care about covid these days. I’m saddened that we can’t just make tonnes of melt blown and make n95s (that imo are more comfortable than normal masks cause they aren’t touching your lips) for anyone who wants them.

For what it’s worth, thus seems correct in my experience. I expected people to just throw on masks and behave “normally,” but the opposite seems to have happened - it serves as a reminder of the seriousness of the situation.

Also an anecdote, but I know many people IRL who have said "The reason we should be able to open back up is everyone knows to wear a mask now."

That doesn't mean people shouldn't wear masks, but... it's definitely the wrong takeaway.

> On top of this, there is decent reason to believe that there's a down-side to mask laws: too many people think that they can behave normally if they're wearing a mask, when the evidence simply doesn't support it.

But you are just making that one up. You don't have studies showing people wearing masks taking more risk than non-masks wearing people. Also, the scientists talk about effectiveness of masks it is not like I had seen a single one claiming it is perfect.

This whole argument is just being manipulative. Trying to pretend it is all about science and precision, when it is nothing like that.

> too many people think that they can behave normally if they're wearing a mask

I don't know how most people are thinking, but it's a pretty wide spread idea that masks (apart from the ones used in health care settings) are more for protecting others from you, than you from others.

If people are thinking like this then it seems logical seeing someone with a mask would remind them that the asymptomatic can be a threat and encourage distancing.

On the other hand, if most people are wearing masks then the few who don't stand out as abnormal, and so others might be wary of them too.

I guess your generalization might be applicable to some states/cities more than others; under current circumstances, I think most people are not seeing what it's like in other places first hand.

Thanks for sharing that article - I wrote it months ago, and there's been plenty more papers that have come out since, but there's really not much I'd change in it today. The science has only become more clear.

I think the 538 article really under-states the evidence. I'm quoted in it, but only about my thoughts on the political situation. I actually pointed out to the author that the science is stronger than any other intervention we have.

So you're Jeremy Howard? Hi. Someone on this thread recommended this article by yourself, on The Conversation, that I managed to miss a couple of months ago (I can't find again the post where the link to the article was given, apologies):

https://theconversation.com/masks-help-stop-the-spread-of-co...

From what I can see in the article, you were first convinced that masks should be worn after watching a youtube video. Then, having been convinced by the video you found more evidence to support your conviction.

I quote from the article:

The research that first convinced me was a laser light-scattering experiment. Researchers from the National Institutes of Health used lasers to illuminate and count how many droplets of saliva were flung into the air by a person talking with and without a face mask. The paper was only recently published officially, but I saw a YouTube video showing the experiment in early March. The results are shockingly obvious in the video.

I have to say, this rings all manner of alarm bells. For example, a video on youtube cannot be seen as evidence of anything, even if it's from the NIH; that video could at best be seen as evidence of a likely mechanism for the spread of the virus, but evidence of a mechanism that could produce an effect is not evidence that the mechanism produces that effect; etc. In short, all this is not "strong science", even if it led to strong convictions.

In any case, we all have to remember -data scientists first of all- that "data science" is not a "science" in the sense that e.g. epidemiology is a science and in a time of a public health crisis, the stage should be left clear for the relevant experts.

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...

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

Osterholm's claims are not supported by the evidence. He claims to respect aerosol scientists, but doesn't have any on his team and none have been involved in his team's work on this issue. He claims that people that are experts in modeling have not modeled correctly, despite having no familiarity with modeling.

On the other hand, our paper includes one of the world's top aerosol scientists, along with top epidemiologists, biostatisticians, and other experts. https://www.preprints.org/manuscript/202004.0203/v2

The rubbish spouted by CIDRAP about masks is very obviously flawed, as you can see for example here: https://www.fast.ai/2020/04/20/skeptics-masks/#what-about-th...

Osterholm has never written any paper about community mask wearing. He is not an informed authority on this issue. The efficacy of masks has now been very clearly shown in multiple studies, e.g:

https://gh.bmj.com/content/5/5/e002794

https://www.thelancet.com/journals/lanpub/article/PIIS2468-2...

https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818

Your lancet article has one mention of the word "mask", and says this:

> We are also unable to explicitly decompose physical distancing measures into constituent components, such as staying 2 m apart, increased hand washing, and face mask wearing, as the relative effectiveness of these components has not yet been estimated.

Did you post the right link?

DanBC is correct: why is he being downvoted?

"Osterholm has never written any paper about community mask wearing. He is not an informed authority on this issue"

And neither are you. Your "paper" on the subject is a joke. I've read it, and I've read the source literature you cite. It is a series of sloppy misinterpretations and mis-representations of the other papers, coupled with the results of running an ad hoc epidemiological model with questionable parameters. It is a quora post, written up like a paper, and pushed to a pre-print server.

You cite papers that are rated by Cochrane (and others) as low-quality, as if they are reliable evidence. You dismiss papers that do not support your conclusions for "lack of evidence", but deflect similar criticisms of your own conclusions with "absence of evidence is not evidence of absence". Quite simply: your analysis wouldn't pass muster at even a third-rate journal, and Osterholm has rightly called you out on it.

It's especially ironic that you say that Osterholm is not an "informed authority" -- he leads one of the country's leading research institutes on infectious disease, has a long history in epidemiology and public health, and spends the better part of an hour-long podcast specifically describing his experience and outlining areas where he has no specific expertise. Say what you want about the man, but he is rigorously honest about his experience. Yet I regularly see you cited as a "mask expert". Where did you do your research, again? Was it when you were getting a philosophy degree, or when you were at Fastmail? Maybe Kaggle has a mask competition?

As for the papers you've cited here: the first link you cite can't separate the effects of social distancing, gloves, masks, and other interventions, and finds mainly that people who take precautions against infection have better outcomes than those who don't. When they actually try to break out masks, specifically, they find that they don't have any effect after illness onset, which should make you doubt legitimacy of the results.

The second link provides no evidence for masks. It is a modeling study.

The third link has the same problem as the first, but worse: it can't possibly separate the effect of masks from everything else that was happening in the examined states at the same time. There is no control.

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.

This brings up an interesting question: why are people around the world still being encouraged/mandated to use cloth masks (whatever their efficacy)?

Surely manufacturers and supply chains for conventional masks have caught up with the demand by now?

Before the spread of disposable masks (a few dozens of years back), the masks were made of cloth. Look at the pictures from the 1918 fever for example. I guess studies were made, it would be interesting to know what people thought.

"Masks" covers various types of respirator (such as N95 or FFP3), and fluid-resistant surgical mask, and surgical masks that are not fluid resistant.

We have lots of evidence for all of these, and most of that evidence doesn't show any benefit for surgical masks that are not fluid resistant.

"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.

> 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.

"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.

The way things have played out in countries that instituted near universal mask wearing is sufficient evidence to start doing it. Evidence doesn't have to be peer reviewed and published in a scientific journal to be useful.

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".

We already have lots of data. Here's the Lancet paper: https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

> 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.

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) you let it sail on by.

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?

> 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=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".

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

"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

Where has science been since quarantine started? Everything is heavily politicized, there's no shortage of bizarro faux-factual evidence for all kinds of nonsense. Someone sent me an article today about the _dangers_ of wearing a mask.

I agree that the rush to penalize people is unfortunate. On the other hand, I'm not sure what we can do (short of a national response) that would be more effective. Making these kinds of policy decisions strikes me as pretty out there for your town council person or even a state level legislator.

Agreed. Pointing out that there's not much data supporting masks has become so political that you get downvoted just for saying it. I've been dismayed by the number of scientists I know who seem to have given up their skepticism on the topic.

If we can't have a rational scientific discussion about facts, we're back to the dark ages.

> If we can't have a rational scientific discussion about facts, we're back to the dark ages.

We're rapidly heading that way. Masks are a political discussion now, not a scientific one. Most other aspects of COVID are the same way. You cannot criticize anything non-politically these days. Even saying "this data is entirely inconclusive" or "the first-order effects of doing this are positive but there are negative second-order effects" is a problem.

I don't have a solution, but I feel your pain.

I fully support your critical thinking about masks.

There's conclusive evidence that masks help on a micro level by stopping droplets.

It's possible that masks also increase aggregate infection rate by requiring a population uneducated in mask usage to apply a potential plague vector directly to their faces.

It will be shocking if science does come back in the future and indicates that mask usage reduces the chance of spreading covid BUT INCREASES ones chance of contracting it.

Mask usage is important and many people don't know how to use a mask properly. If someone puts a cloth mask on backwards they're inhaling a virus that stays on surfaces for days.

Masks may also increase the chance of infection by causing people to put their hands near their face more often to adjust or don the mask.

Even in the most recent World Health Organization report:

"At the present time, the widespread use of masks by healthy people in the community setting is not yet supported by high quality or direct scientific evidence and there are potential benefits and harms to consider "

Additionally Sweden had no mask laws and its infection rate has stabilized while place with mask laws like Cali and Washington have skyrocketing rates of infection.

Masks have become a religious war and most people accept it without question and have never looked a single shred of research from legitimate sources that aren't news media based.

I personally think it gives people the feeling of power over a powerless situation.

I just hate to see laws forcing people to do something backed by weak science and I hope this isn't like Thalidomide or Lead paint where experts validated something based on weak science that turned out to be wrong.

> It's possible that masks also increase aggregate infection rate by requiring a population uneducated in mask usage to apply a potential plague vector directly to their faces.

If there's SARS-CoV-2 on your mask, there'd be SARS-CoV-2 on your unmasked face if you weren't wearing one. Right?

There's no uncertainty that unfit around the nose masks have giant centimeter squared open gaps. For protection of the wearer they're not good. Objectively in tests with similar gaps the rating is N30-N40.

There needs to be a strong and lasting push for increased N95 mask production or at least purchasing. Pretending that ineffective unfit masks (of any material!) can fill the role of real masks does real damage and needs to stop. If everyone could rotate a set of N95 masks when indoors then spread could really be stopped.

Even a synthetic/cotton/synthetic mask would be quite effective if they'd just incorporate metal nose bridge with foam.

Better-fitting masks made of non-woven cloth might help, but the focus on N95 and the confidence that "spread could really be stopped" by wearing them is exactly the kind of overconfidence the article warns against. There's no known evidence supporting the idea that good masks are a silver bullet.

N95 is what doctors wear to generally not get sick while working. Had there been enough of them, it would likely do a lot.

But back to real world, cloth masks is what we got.

I think I've read that N95 masks are in fact inferior to other kinds for "civilians" and I don't altogether believe this is propaganda to conserve them. It makes sense, doesn't it, that N95 masks filter air coming in, not out? My impression is the valve in masks that have them is a sign that it's not protecting others from you - the point is to let air out easily.

There is an asymmetry between healthcare workers and the public - in a hospital, you have one non-infected person surrounded by a lot of infected people, while elsewhere, it's the opposite.

I see a lot of people wearing surgical masks, and having just googled and read a page on 3M's site, it mentions:

"Surgical/procedure or “medical” facemasks are designed to help keep spit and mucous generated by the wearer from reaching a patient or medical equipment. Some surgical/procedure masks do contain filter media but as they may not be designed to form a seal to the face, and have not been certified to meet all of the performance standards of a respirator, they should not be used to help reduce exposures to airborne particles"

I feel like this is a simple difference that people can't comprehend due to a very primitive equation of protecting oneself and protecting others. There is a difference and it should inform our behavior.

Edit: to clarify, I meant to contrast the N95 masks with a valve, that seem to make more sense for health care workers, with the surgical masks that seem to make more sense for the public.

This isn't about protection of the wearer, it's about prevention of spreading.

In that sense what has changed is the best guess at the main mechanisms of spread. Specifically the amount of spread mediated by large spittle on surfaces versus via aerosols. It has become increasingly clear from large spreading events (meatpacking with gloves/hygine in place, singing events being really bad) that aerosol spread is primary.

So the protection that unfitted cloth masks provide, and it is some, isn't as much as you'd think against the primary mechanism of spread. Wear an unfit mask and sing and it's as bad as normal singing.

I'm not arguing for not wearing bad masks when it's all you have. I'm saying it's super important that everyone starts getting real masks so we don't have to keep doing shelter-in-place every time spread goes exponential in an area again.

It's currently believed SARS-CoV-2 spreads primarily via droplet, not aerosol.

Singing propels droplets further (as does any heavy/forceful breathing), and choirs tend to sit close together. Six feet likely isn't enough for a choir.

As for meatpacking, I've heard several interviews with workers that indicated the plants were only handing out one mask per shift, and they'd pretty quickly get contaminated by gore from the work, meaning in practice folks weren't wearing masks.

Right. I just want to further highlight that "aerosol," in the context of medical journals, has a specific meaning, and that your lungs generally aren't capable of aerosolizing the virus into small enough matter to qualify. The spread from coughing, sneezing, etc, is still considered droplet-based spread, NOT aerosol. Droplets can still be suspended in the air for a matter of seconds, however.

MAGZine says>" your lungs generally aren't capable of aerosolizing the virus into small enough matter to qualify."

No, every exhalation is aerosol and filled with particles from your body. They slip by the mask's edge and through it's seams. No mask that isn't airtight can stop those particles.

Droplets are emitted when you cough or sneeze and are much larger. Droplets are like boulders, aerosol like marbles. Viruses are tiny compared with aerosols and ride on both aerosols and droplets.

No, it was at the start. Then after a few months everyone who was reading the journal articles became aware that aerosol was the mechanism of spread and that normal human behaviors created aerosols that worked for this. The WHO and governments have lagged because they don't want people hoarding effective masks when hospitals need them more. But they can't deny reality for much longer and it's time to manufacture more instead of lying about spread mechanism.

"239 Experts With 1 Big Claim: The Coronavirus Is Airborne" https://www.nytimes.com/2020/07/04/health/239-experts-with-1...

>The W.H.O. has resisted mounting evidence that viral particles floating indoors are infectious, some scientists say. The agency maintains the research is still inconclusive.

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