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Comment by cmiles74 | Hacker News Reader

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.

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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.

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