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Please don't use allcaps for emphasis on HN. This is in the site guidelines https://news.ycombinator.com/newsguidelines.html.

No one honest can, because masks do help. What's not clear is how much they help. They'd have a huge effect on large droplets, but potentially a very small effect on bioaerosols. Until we know more about how COVID19 typically spreads, we don't know how important they are.

In contrast to the intentionally dishonest UMN fluff PR piece, that's what the NAP paper it claims to summarize says.

The one really big effect not talked about is that it also means I can't unconsciously touch my mouth or nose. Remember the "don't touch your face" campaign?

"In contrast to the intentionally dishonest UMN fluff PR piece, that's what the NAP paper it claims to summarize says."

The article title is "data do not back cloth masks to limit Covid-19".

The NAP paper says:

"The evidence from these laboratory filtration studies suggests that such fabric masks may reduce the transmission of larger respiratory droplets. There is little evidence regarding the transmission of small aerosolized particulates of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19. The extent of any protection will depend on how the masks are made and used. It will also depend on how mask use affects users’ other precautionary behaviors, including their use of better masks, when those become widely available. Those behavioral effects may undermine or enhance homemade fabric masks’ overall effect on public health. The current level of benefit, if any, is not possible to assess."

It seems like an entirely accurate summary of the contents of the paper.

"Can someone explain to me how placing a barrier in front of your mouth and nose can possibly be a BAD idea when the purpose is to reduce the entry of particles into the system?"

There are a number of reasonable arguments. Just a few:

* people who wear masks touch their face more often, which leads to greater infection (I personally observe this every day).

* masks give people a false sense of safety, and cause them to reduce social distancing.

* masks increase risk of infection unless donning and doffing procedures are followed correctly.

* telling people to wear masks causes them to seek out medical masks and N95 masks that are in short supply, and should be reserved for professionals (also personally observe this every day; people are walking their dogs in Manhattan wearing N95 masks, while hospitals literally beg for new masks).

If anything the fact that I have a mask on constantly reminds me that I should not be touching my face. Every time I hand motions towards my face I remember that I have a mask on.

I am citing the most common arguments made by experts in the field.

Unless you record yourself and count the number of times you touch your face while wearing a mask, your recollection is unlikely to be objective or accurate.

It is not hard to come up with a laundry list of such arguments.

Here, I made another one—

> If you are wearing a mask while others are not, they are likely to ask you about it, which makes it more likely for you to talk in their presence, thus increasing the chance of transmission.

Given how the authorities flipped their advice in barely a month, despite having the same laundry list of arguments, shows that the arguments were more of a deflection than something that was properly incorporated into the cost-benefit analysis.

"Given how the authorities flipped their advice in barely a month, despite having the same laundry list of arguments, shows that the arguments were more of a deflection than something that was properly incorporated into the cost-benefit analysis."

It's also consistent with a recommendation made for non-scientific reasons. The science here hasn't changed, but the recommendation has.

I wore masks in public early.

Everyone on the street observed social distancing with me. As with most anti-mask excuses, statements didn't match reality.

...or representative of the majority.

I see people adjusting their masks frequently, which is evidence against your theory.

An anecdote is not data.

The goal of the parachute, as you say, is to redirect air. And poorly made or fitted masks do just that. But the goal of a mask is to stop or filter particles. Redirected particles simply change the direction that you blow your infection in. Good for people in front of you, less good for those beside you.

The term is “blow by”, and it’s worth at least learning about.

https://apps.who.int/iris/rest/bitstreams/1274280/retrieve:

”The use of medical masks in the community may create a false sense of security, with neglect of other essential measures, such as hand hygiene practices and physical distancing, and may lead to touching the face under the masks and under the eyes”

(Note that infection can take place via your tear ducts. https://www.drtavel.com/blog/can-you-catch-a-cold-through-yo...: “Rubbing your eyes after coming in contact with an infected person is one of the most common ways to catch a cold.”)

The only thing I could imagine is that the masks could make it worse because of something else. Say, for a runner gettin x% less O2 is worse, risk wise, than to use the mask for viral protection

This was not in the article, I am just speculating on a possible reason (not applicable here).

BTW our gouvernement (French) was telling us that story of no masks for the first weeks and it was already ridiculous at that time.

The problem is that the worst thing that you can do during this pandemic is touch your face. There is a lot of evidence that people who are not used to wearing masks increase the incidence of touching their faces to adjust the mask, talk, eat, even... cough and sneeze. Proper hygiene is far more important, wash your hands and cover your mouth when you cough or sneeze. Hospitals have entire procedures for equipping and doffing PPE, the public doesn't.

Not arguing for/against masks, merely pointing out the analogy. For your parachute analogy. Imagine that its given the parachute will have very large holes (similar to the droplets being very very small). Its useless having a parchute in that case.

I am pretty sure that a parachute with holes will still have reduced terminal velocity than not having a parachute.

I get your argument but unlike a man crashing to death, we are playing a probability game here. Viral load also matters, even if you can stop some of the virus from entering, it can only help.

Imagine that having the mask encourages you to go out and be around people.

If you would otherwise self-isolate if you didn't have a mask, the mask has increased your chances of getting yourself and others sick.

This is because the advice was delivered in a hare-brained manner and a month late.

It should always have been a combination of mask wearing from day 1 and stopping any large gatherings. Combine that with social distancing and you get most of the benefits. Now we have already infected so many people and are trying to close the barn door when the horse has long fled.

Before the lockdowns people were going about their merry lives WITHOUT masks. If they were doing exactly the same things but WITH masks, we would still be better off.

A coordinated advice in this case is important. Without a central authority advising for masks, people who do choose to wear them look like loony conspiracy theorists, but if there is central guidance for doing it, it quickly changes public perception.

The mask advice should have come in February, followed by bans on large gatherings (25+ people or some number), and then the lock downs could have come in a limited fashion in March as needed.

All those cute videos of cutting TShirts and socks and what nots to make masks could have been shown in Feb and people would have used them. Instead the authorities chose to tell such a stupid lie that it's almost insulting to our intelligence.

Citation for such lies?

https://slate.com/news-and-politics/2020/02/surgeon-general-...

More specifically this tweet then on 29th of February 2020:

  https://twitter.com/Surgeon_General/status/1233725785283932160

  U.S. Surgeon General
  @Surgeon_General
  29th Feb.
  Seriously people- STOP BUYING MASKS!

  They are NOT effective in preventing general public from catching #Coronavirus, 
  but if healthcare providers can’t get them to care for sick patients, it puts them and our communities at risk! 
  http://bit.ly/37Ay6Cm

But wasn't this appropriate for that situation and time? If there were oversupply, sure, and enough time to train the public, and maybe some evidence that masks are not detrimental to contagion for untrained people. There's also a huge difference between a highly contagious situation, and one after physical distancing have halted the spread. You would want the real masks used where appropriate.

What is surely to happen after this debacle though, is that many official recommendations and plans will have to account for pandemic outbreaks and remedy many of the shortcomings of current funding cuts.

> "They are NOT effective in preventing general public from catching #Coronavirus"

This is true. Masks don't protect you from catching COVID-19.

Masks may lower (but not eliminate) spread of virus particles. We don't have any evidence that this reduces infection rate, but it's plausible, at least for droplets.

If the virus spreads mostly by aerosol however, then mandated masks are probably counterproductive, because if the government says "wear masks" the people will hear "wear masks and you'll be fine", because that is what they want to hear.

All you smart rational types out there might not think like that, but I have heard this reasoning first hand from ordinary people. It's a real problem.

Masks protect both directions. Some masks protect better than others. If masks don't protect you from getting COVID, why do healthcare workers wear them, and why should we reserve for them a product that doesn't work?

I understand wanting there to be enough for HCWs. If so, say that without the lie. If there aren't enough for HCWs, restrict purchase by the general public and say that they will be available to the general public when there are adequate supplies.

When the health authorities lie to the public, they lose credibility, and they need that credibility if they're going to ask people to do extreme things like not leave their houses for an extended period of time.

It's really just like a condom. They work, some better than others, but none are perfect. The general public can understand that.

> Masks protect both directions.

Cite me some evidence that shows that simple (non-FFP) masks or surgical masks protect the wearer against any virus. To the best of my knowledge, There isn't any such evidence and it's not scientifically plausible that they would protect.

> If masks don't protect you from getting COVID, why do healthcare workers wear them, and why should we reserve for them a product that doesn't work?

Because healthcare workers do get infected (a lot) and you don't want them to spread the virus (or other pathogens) around either.

We also need to differentiate between FFP masks which may offer some protection against viruses and surgical masks, which do not. It is mainly the FFP masks that are in short supply.

> When the health authorities lie to the public, they lose credibility, and they need that credibility if they're going to ask people to do extreme things like not leave their houses for an extended period of time.

Maybe, but that statement I quoted is strictly not a lie.

> It's really just like a condom.

No, it isn't, not even close. It's like avoiding pregnancy by wrapping your dick in a piece of linen. It just doesn't work. There's no evidence that it works. It's not plausible that it would work.

> The general public can understand that.

You, presumably intelligent and well-educated, don't even understand it. You still believe the mask protects the wearer when it does not. I have no hopes the general public will understand it.

To be clear, I'm not against wearing masks because I hope that it can reduce droplet infections and it's a net benefit. That's just my hope though, not my firmly-held belief.

Sure, here's a Cochrane review that shows the opposite of what you say. Have you looked at the scientific literature on this? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2190272/pdf/bmj...

Even a surgical mask provides protection to the wearer. A professional-grade surgical mask provides N95 level filtration, it just doesn't seal to the face like an N95. That means that some of the air coming in will not be filtered. However, much of it is, and larger, non aerosolized ballistic droplets will be stopped and absorbed by a mask.

> Sure, here's a Cochrane review that shows the opposite of what you say.

It doesn't.

> Have you looked at the scientific literature on this?

Yes, I have, including this particular review as well as several of the reviewed papers.

I have yet to find a single convincing study that shows that simple masks protect the wearer against viruses. If it existed, people would be waving it around and governments would have no reason to not ask people to wear them. Simple masks were never in short supply.

This review makes abundantly clear that virtually all the studies are of poor quality. Note that the effect found in this review is not that large (+13% over washing hands) whereas the effect of wearing a gown is much larger (+27% over washing hands). Yet I haven't seen any big discussion on what kind of gowns people should be wearing out in public.