[Will_Parker]

> There is no scientific evidence they are effective in reducing the risk of SARS-CoV-2 transmission

It's a disease spread by exhaled droplets. How the heck could masks _not_ work? Why has common sense, as an acceptable way to obtain knowledge, died in the general public?

[dougmany]

I am always amused at how effective the There is no scientific evidence line is. That just means it has not been studied. No one has studied masks on this specific strain? It's new for crying out loud.

[rumanator]

> No one has studied masks on this specific strain?

You're misrepresenting the entire problem.

The main unknown is not that protective equipment helps protect. That's a absurd strawman.

The main unknown is the impact on the likelihood that someone not educated or trained or experienced in facing biological hazards would contract a virus when knowingly exposing themselves to the virus while wearing said protective equipment to the best of their personal abilities, discipline, and knowledge.

That's the main unknown.

Meanwhile, do keep in mind that the effectiveness of condoms to stop unwanted pregnancies, which are pretty much widespread and even covered by classes included as part of mandatory public education, has been as low as 79% if poorly used.

https://www.webmd.com/sex/birth-control/birth-control-condom...

[a-saleh]

I'd say the condom analogy is great, and with R around 3, reduction in transmission beyond 70% means the damned infection rate grows no more.

[rumanator]

What? That makes no sense at all. Just because condoms can have low effectiveness it doesn't mean that wearing face masks makes the epidemic go magically away. What kind of twisted logic is that?

The main point is that face masks are known to not be full proof, and badly worn ones might even be less effective than not wearing anything as they provide incentives for people to repeatedly touch their faces. More importantly facemasks create a false sense of safety and thus invite unwitting people to needlessly expose themselves to the virus.

If you want to understand the problem, think of combat helmets. You can put one on and safely walk into a war zone, right?

[a-saleh]

Ok, then that is the exact thing where you misunderstand.

The mask is not protecting you. It is protecting others from you.

If you were right, and wearing masks badly would have been worse than not wearing them at all (i.e. w.r.t. touching your face and all that), then countries that opted for mandatory mask wearing would be worse off and they aren't.

Related: https://www.preprints.org/manuscript/202004.0203/v1

[DanBC]

There is a lot of work on respiratory viruses and masks, and none of the RCTs can find a benefit of wearing masks.

> No one has studied masks on this specific strain? It's new for crying out loud.

Yes they have. Here's one where they take four patients who have covid-19 and fit them with masks and ask them to cough onto petri dishes. They find covid outside the masks.

https://www.acpjournals.org/doi/10.7326/M20-1342

[dougmany]

It is interesting that the cotton masks were more effective than the surgical mask:

>The median viral loads after coughs without a mask, with a surgical mask, and with a cotton mask were 2.56 log copies/mL, 2.42 log copies/mL, and 1.85 log copies/mL, respectively

My point was that if the statement read Scientific evidence shows masks are not effective it would means something. The lack of evidence showing effectiveness does not disprove effectiveness.

[ceejayoz]

"This article has been retracted. See Notice of Retraction."

Yeah, maybe don't go around citing that one.

[themaninthedark]

This was binary test. It looks like they were testing if Covid-19 passed through masks or not. They did not look at N95 masks, nor did they look at seeing if the viral load was decreased.

"This experiment did not include N95 masks and does not reflect the actual transmission of infection from patients with COVID-19 wearing different types of masks. We do not know whether masks shorten the travel distance of droplets during coughing. Further study is needed to recommend whether face masks decrease transmission of virus from asymptomatic individuals or those with suspected COVID-19 who are not coughing."

[jdc]

Looks like the authors retracted this one!

[ex3ndr]

Actually it was studied for flu and N95 masks made no difference at all: tested on nurses during a year.

[jaredklewis]

Because common sense has been used to justify all manner of things which are thoroughly debunked. Blood letting, bed rest, alcohol for pregnant mothers. Common sense doesn’t have a great track record.

[catalogia]

Common sense has an excellent track record. What is it that keeps you from walking into traffic without looking, touching fire, or eating broken glass? Common sense.

Obviously common sense will sometimes lead you astray. But it kept our ancestors alive long enough for us to be here, and it stops most of us from doing life-ending stupid shit every day. It's not a silver bullet, but nothing is, not even the scientific method. If you went looking for empirical peer-reviewed studies before making all your decisions, you'd never get anything done. "Should I poke my eyeball with this fork? Common sense says no, but fuck that shit. I better consult pubmed..." "Should I cough into Grandma's face, or into this handkerchief?"

[bunje]

It's explained in point two. We're talking about large quantities of people here. Technically mask blocks droplets. But if you tell everyone to use a mask, does it reduce transmission on average?

[Will_Parker]

What's your plausible scientific reason that blocking droplets doesn't reduce the chance of spreading the virus? My prior is, it does, based on my experience of the mask getting wet when talking.

[bunje]

Again, I'm not questioning that. Mathematically, does "tell people to use masks" imply "less new cases"? E.g., what if people decide to spend 5x more time with other people on average due to a mask requirement making them feel safe? That could easily cause more cases.

[rumanator]

> It's a disease spread by exhaled droplets. How the heck could masks _not_ work?

You should really get some information on the topic you're discussing, because either you are oblivious to the point you're trying to argue against or are disingenuously misrepresenting what was actually and repeatedly said.

The main argument against wearing any protective equipment, including latex gloves which you casually omitted, was that a) it provided a false sense of safety that ironically ends up increasing the risk of contagion of everyone around you, b) create incentives for those wearing the gear to repeatedly touch their face with a much higher frequency, c) deplete the supply of protective equipment and thus deprive healthcare workers who directly contact with covid19 patients from having basic safety measures.

[Will_Parker]

So how does it not work? I talk, mask gets wet. Doesn't it mean it's blocking some of the droplets from spraying out? Why not?

[DanBC]

In healthcare there's a bunch of stuff that sounds plausible, and then we do the research, and we find that it doesn't help or it causes harm.

Evidence based medicine isn't there to stop crystal healing. It's there to work out whether knee arthroscopy is better than placebo. (For some patients it isn't).

Masks have a plausible mechanism of action. But they also have plausible mechanisms of harm: they may reduce social distancing; people touch their face more often when wearing a mask; most people don't know how to put on or take off the masks; most people don't have a safe place to store the mask when it's not being worn; etc. We don't know if the benefits outweigh the risk, because we don't have good quality evidence yet.

Here's some papers:

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

> 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).

Here they say that distancing does work. But when talking about N95 masks they only say "could" work, and for cloth masks they say they have low certainty. Later in the paper they say they need more and better evidence for masks.

https://www.publish.csiro.au/hc/pdf/HC15950

Have a look at the table on page 2. They've looked at RCTs and they've found no benefit for masks. They go back and look at other data and they claim to find a benefit, which is why masks are recommended for HCPs.

When you say "it's transmitted by inhaled droplets" you didn't say how it's caught, and here it's clear that you think it's by breathing in those droplets. That's one route. The other is via the eye. Or the droplets land on surfaces and are transferred by hand to the eye or nose or mouth.

https://www.cmaj.ca/content/188/8/567

> Transmission of acute respiratory infections occurs primarily by contact and droplet routes, and accordingly, the use of a surgical mask, eye protection, gown and gloves should be considered appropriate personal protective equipment when providing routine care for a patient with a transmissible acute respiratory infection.

When someone coughs the droplets are expelled in a range of sizes. Some of these are trapped by cloth masks, but not all.

https://www.cidrap.umn.edu/news-perspective/2020/04/data-do-...

[HideousKojima]

The Lancet's credibility is kind of in the toilet right now thanks to publishing that Hydroxychloroquine study that appears to have had the data pulled from thin air

[rumanator]

> The Lancet's credibility is kind of in the toilet right now thanks to publishing that Hydroxychloroquine study

This statement is utterly absurd. The credibility of an entire scientific journal with nearly 200 years of operation is not shaken by accepting a scientific paper that after being subjected to peer review didn't held to scrutiny.

This line of critisicm reveals a profound ignorance regarding the whole scientific establishment. I mean, only someone entirely ignorant and oblivious to the whole scientific process would assume that passing the review stage of a scientific journal is a rubber-stamp of approval that all observations and ideas and conclusions represent the final and unquestionable proof. That's now how it works. Papers are published to expose ideas to peers and thus subject them to scrutiny. Some ideas don't pan out, some might be misguided, and there might even be some instances of straight pure scientific fraud. But that's not what the aim of the acceptance process, is it?

The upside of this sort of case is that suddenly we have random people caring about science and the scientific process. It's a shame though that they don't educate themselves on the very basics and instead are more interested in dragging institutions through the mud.

[pen2l]

It looks bad right now, yes, but Lancet and NEJM both had the two studies retracted, and both will carry their reputation.

Retractions happen in all sorts of journals. Sadly, they will keep happening. Journals need to impose a page limit, alas a paper cannot describe its methodology down to every last detail, peer review can only do so much when you have bad actor intent on passing through.

This blip aside, it doesn't take away the fact NEJM and Lancet both have a history of being great sources of information, indeed they are still _the_ place doctors go to to get informed. I don't see that changing.