I didn’t think they said masks don’t work, but rather:

a. Masks mostly help people who are infected to not spread it widely (by catching their respiratory droplets, presumably).

b. There’s a global shortage and doctors and nurses really need them.

All I’ve been hearing locally is of course they help - hence the medical professionals need them - but that they don’t make as big of a difference if you’re a healthy person out in the world of mostly uninflected individuals, so please don’t buy any and let the doctors and nurses have them instead.

The message from the community was to ensure mask supply for medical staff first. They are both more at risk themselves and a risk for others due to the large numbers of contacts.

Once supply is secured everyone should be educated about correct use and be encouraged to wear them.

Most of Asia already has a culture of wearing masks and existing supply chains. Europe/US did not and it takes a while to establish.

I have been asking myself the same question. I think it comes down to two reasons:

1. Masks are in short supply and they believed they could save them for healthcare workers by convincing the general population they don't work.

2. If you are measuring efficacy, the general population won't reach the same level as a healthcare worker because they have not been professionally fitted and trained in on/off procedures. So instead of reducing risk by 95% the average person would see something like a 70% reduction, and they decided "perfect is better than good enough".

Nobody said that they don't work. But they are not effective for the average person because a month ago there were so few confirmed cases in the US that it would be extremely unlikely that you would ever encounter a COVID positive person.

On the other hand, healthcare professionals have to deal with infected patients all day. Suppose a mask is 95% effective on a healthcare professional, and 90% effective on a normal person. But the healthcare professional is in close proximity to a coronavirus patient nearly all the time. Without a mask, there might be 20 chances of infection every day for them. A mask would prevent 19 chances of infection.

For a normal person, they might encounter one CoV positive person per day. That means that a mask prevents 0.9 chances of infection. This is much lower than 19.

This math is off because I didn't account for mask changings, etc. A healthcare worker should change their mask more frequently than a layperson. After accounting for mask changes, though, I'm sure that the healthcare workers still get more benefit.

If they say "Masks work" when it only works 70% of the time then a lot of people will get sick despite wearing masks, there'll be a big public outcry, and people won't trust the WHO in the future.

Maybe. Or they can just lose all trust instantly by claiming like the CDC, that they don't work. Now people who think will never trust the CDC ever again. Not sure what the WHO's wording was, but any organization not encouraging mass mask use cannot be trusted by anyone with a brain. Just because something isn't 100% effective, doesn't mean it's not effective. Only children and idiots think so. Unfortunately, we're surrounded by idiots.

It would certainly be a failure if it is communicated that mask wearing prevents you from getting infected. They reduce the risk of infecting others more than they reduce the risk of getting infected.

A 20% reduction in infection risk is already substantial and worth it. If there is a 50% reduction in infecting others, mask use alone could replace most social distancing measures.

As opposed to public outcry from them saying masks don't work while countries with mask usage fare better?

if you look up "does wearing a mask" on google, you'll find dozens of articles discussing the mixed messaging, how some countries encourage it while others discourage it, etc. so there's tons of back and forth with reasons/studies cited on both sides.

I've yet to see a definitive answer but essentially, one of the big arguments is that if you don't know that you have COVID-19 and since it's asymptomatic when you're already infectious, wearing a mask in public may help prevent the spread to others.

Not quite, but it's certainly been confusing advice, if you can call it advice at all: https://blogs.bmj.com/bmj/2020/03/11/whos-confusing-guidance...

There are two quite different usages:

1. Diminish the number of viruses that travel out of your mouth and land on the surroundings, there to be picked up by some passer-by.

2. Prevent viruses in your surroundings from reaching you.

AIUI the WHO and others have said quite loudly that masks don't work reliably for the second case.

> AIUI the WHO and others have said quite loudly that masks don't work reliably for the second case.

what does "not working reliably" mean?

People are stupid and use them wrong. I saw people while out shopping this week who absolutely did not handle their masks correctly; while the mask still probably helped them, I’d rather see that mask go to a medical professional who will use it correctly, especially in times of extreme shortage.

Not sure to keep the wearer from catching the disease. As opposed to merely improving the wearer's chances.

WHO doesn't only say things they are absolutely certain about - e.g. https://twitter.com/WHO/status/1217043229427761152

Also, not the most reliable source, but I've heard claims that initial viral load may determine the serverity - a mask could help here too: https://www.dailymail.co.uk/news/article-8166867/How-large-v...

It was mostly an effort to prevent panic buying like what happened with toilet paper. There are not enough masks produced even in a year to solve this, so they. Need to focus on medical workers having access.

You left out the word "lied"

From hearing nurse aquaintances talk on Facebook, listening to This Week in Virology, etc it seems that the idea that surgical masks don't protect you from getting sick is very pervasive in the western medical community. And from a medical community standpoint it's true! If you're working with sick people every day and just use a surgical mask you'll probably get sick eventually. But in the game of telephone that is horizontal knowledge transfer "Surgical masks are generally insufficient for consistent protection in a medical setting" becomes "surgical masks don't work" and then becomes "a surgical mask won't protect you when you're going to buy groceries."

There’s a big difference between a nuanced message and a lie. If you see The WHO statements as a lie, you lack the understanding of the situation needed to make a thoughtful decision, and it’s for the best that you were misled.

People who read the news and get “masks don’t work” out of it should not be using masks until there are enough available for professionals who need them.

If there are tons of studies showing that homemade masks prevent virus spread, almost no evidence to the contrary, and they tell people not to wear even homemade masks, I don't know what else to call it but "lying".

How about I meet you half way and call it an "incompetent noble lie".

https://docs.google.com/document/d/1HLrm0pqBN_5bdyysOeoOBX4p...

Can you please point to where WHO is saying people shouldn’t use homemade masks? I’ve never seen that claim, but if it’s true it indeed doesn’t make sense. I’ve only seen CDC dissuade people from using surgical and N95 masks.

Perhaps there’s concern that if CDC or others advise people to use homemade masks, people who actually do need N95 masks (e.g. severely immunocompromised) will think that works for them?

Edit: there’s also the moral hazard aspect to consider: if people think wearing homemade masks is enough to protect them, they’re probably a lot more likely to ignore quarantine or social distancing. If the masks aren’t 100% effective and are used wrong, that could be worse than just staying in and social distancing.

"You should only wear a mask if a healthcare professional recommends it."

A blanket statement against all types of masks without qualification.

https://www.cdc.gov/coronavirus/2019-ncov/faq.html

Right, the CDC FAQ seems to say don't wear masks.

However the CDC also says if you "think you might have COVID-19", you should "wear a facemask" "to help protect other people in your home and community." "You may need to improvise a facemask using a scarf or bandana."

https://www.cdc.gov/coronavirus/2019-ncov/if-you-are-sick/st...

Seems to me we should all assume we "might have COVID-19" and therefore follow CDC's advice: wear a facemask of some kind to protect other people.

BTW, that bit about the "bandana" was just added in the last week because people like me keep complaining about their guidance.

Because bureaucracies often accidently transform "not 100% guaranteed certainty" into "doesn't work"

Other things WHO has said so far:

* Preliminary investigations conducted by the Chinese authorities have found no clear evidence of human-to-human transmission of the novel #coronavirus (2019-nCoV) identified in #Wuhan, #China

* WHO did not recommend any travel or trade restriction based on the current information available

Seems like they would, based on their recent track record.