It's funny you use mask wearing as an example -- when the CDC told us that masks would not protect us[0] there was no theory to back it up and no homework to do, it was just a realpolitik lie. Be cautious of experts wearing the skin of science.
It's been +6 months of Coronavirus, and still people don't get this right:
Wearing a mask (for the most of us not working in healthcare) prevents you from spreading the disease. It's not for protecting yourself, but for protecting others.
Since you can spread the disease even without having symptoms, and showing symptoms can take up to 15 days, then you should wear a mask, specially in closed, crowded spaces.
There is no hidden agenda, conspiracy or whatever satisfies your imagination.
>There is no hidden agenda, conspiracy or whatever satisfies your imagination.
Early on, the CDC and WHO were both saying NOT to wear masks. The hidden agenda at that time was to prevent a run on masks that might prevent health care workers from having enough. That was the lie.
Your claim is that CDC / WHO lied about the efficacy of masks.
CDC / WHO claim that they didn't have good quality evidence that they could use to recommend mask wearing.
It should be really simple for you to prove your point: post a link to any meta-analsis or RCT of mask wearing that shows a benefit. This would be the evidence that WHO or CDC should have used to make the recommendation but chose to sit on. Before anyone says these studies don't exist: they do, there are lots of studies of mask wearing.
They didn't just make no recommendation based on weak evidence. They recommended against wearing them [1].
I'm not sure what your last paragraph is supposed to say. Are you claiming there are lots of studies of mask wearing and the preponderance of evidence is that they don't help?
CDC said "don't wear masks". CDC said they had no evidence they could use to recommend mask wearing.
You're claiming they did have the evidence, but they hid that because they were lying about the efficacy of masks.
If you're right it's really easy to prove: post a link to the evidence that masks work. Post a link to any meta-analysis or RCT that shows a benefit of mask wearing.
> Are you claiming there are lots of studies of mask wearing and the preponderance of evidence is that they don't help?
You're claiming that there are studies; that the studies show that masks help; and that the quality of the evidence is strong enough to make a recommendation that everyone should wear a mask.
Post a link to one of these studies.
(This, btw, is a common theme in these threads. Everyone says these studies exist, no-one ever posts a link to them. The only time someone did post a link i: the study was published June 2020 and ii: it didn't say what they thought it said).
True, but not 100% accurate. You can get it also through your eyes, or by touching something infected like a door knob and touching your eyes or mouth.
> CDC and WHO were both saying NOT to wear masks
I believe they were saying to not rush and PURCHASE masks, that is different to say "NOT to wear masks". It was the period they were appealing to common sense: to keep a distance from others and cough in a kleenex or in your arm, and stay at home.
>If you are healthy, you only need to wear a mask if you are taking care of a person with COVID-19," the WHO guidelines read.
That was the early advice, countries with experience in pandemics like Korea knew this was bad advice. Seems to have been generally common knowledge that wearing masks reduces the chance of both contracting and spreading, which is why doctors wears masks
Various local administrations (at least here in Canada) did, justifying it by saying you'd be more likely to touch your face to adjust it. It was simply a misinformation campaign to avoid supply shortages but the resulting erosion of trust is hard to counteract.
There are many different types of masks. Masks in the health care context are designed to protect the wearer. N95 masks block 99.9% of incoming nanoscale particles, but are designed to be easy to breath, so have valves or release-seals on the perimeter so that you can breath out with no resistance.
i.e. they are not at all designed to protect others from yourself, but they do help.
Cloth masks provide <10% filtration efficacy for breathing in, so they are not appropriate for the industrial/medical arenas.
Anything in front of your face helps stop large droplets.
Medical people wear eye protection because covid enters through the eyes as well.
Thanks. Yes, I clarified some points in other answers.
My message was intended to be as simple as possible, because a healthcare worker won't be even questioning all these facts after six months of life/death struggle.
> Wearing a mask (for the most of us not working in healthcare) prevents you from spreading the disease. It's not for protecting yourself, but for protecting others.
This is true for surgical and cloth masks but you can also buy better masks that also protect the wearer.
I am not sure science is clear about "you can spread the disease even without having symptoms". I've seen a couple back and forth arguments but nothing conclusive.
Also, 15 days to get symptoms is an extreme outlier. Median is around 5 days.
Anyway, being able to spread without or very mild symptoms is the main thing of this disease, and this is why it can saturate hospitals in no time. Otherwise, if you are just contagious when in bed and with fever, the spread will be lower.
> 15 days
I said 'up to'. And most countries use 15 days to measure quarantine effects. In Italy we had a very high peak (~5K infections/day), and because of those measures (and some good sense) we managed to lower it to 200/day, totaling 13K infected.
> Wearing a mask (for the most of us not working in healthcare) prevents you from spreading the disease. It's not for protecting yourself, but for protecting others.
How does the mask know in which direction it is providing protection?
From what I understand, it is the size of the droplets. The ones leaving the wearer's mouth are much larger, therefore higher chances of the mask stopping them. The ones that are lingering in the air are smaller, which most face coverings (ie, not proper fitted masks) have lower chances of stopping from entering a wearer's mask.
The CDC is full of doctors. Who, when asked "does <x> help against <y>?" always think of bloodletting or lead-against-malaria and answer "no", unless they have empirical evidence (studies) rejecting this so-called "Null Hypothesis".
That approach wasn't particularly smart in this case. But it's so fundamental to medicine today, precisely because the alternative killed an untold number of people over centuries, that people steeped in it were not able to overcome these priors.
The idea of this having been a strategy to ration limited supplies is rather widespread, obviously. And if you look at a timeline, you will notice that it was mentioned in the mainstream press in the very first articles reporting about the guidance on masks.
So I believe what happened actually went the other way around: experts were looking for arguments to support their guidance against mask usage. And because the argument above doesn't satisfy many people, they came up with their own conspiracy theory about their "true" reasons. Mentioning it, with a wink, allowed them to use the one argument that people would understand. And everyone ate it up!
> That approach wasn't particularly smart in this case.
Woah wait where did that come from? Yes it was smart. It looked bad but they were behaving correctly. And before you argue that masks don’t have any downsides (which I was saying when I originally started wearing them) it’s really easy to accidentally contaminate your mask and now you’re breathing through whatever got on it. I’ve done this by mistake at least once now and was sick for a week because of it.
It's true though, the mask does not protect you from coronavirus, only a FFP3 respirator will. It prevents you from touching your face and coughing/breathing at others, which is the most common medium. They obviously shouldn't have discouraged the public from wearing masks, but it was not a lie - preventing spread of disease and contraction of disease are very different things. I wouldn't want my doctor to only wear a mask.
I think in times of crisis (and in general to some extent), it is difficult and non-advantageous to aim SOLELY to be technically correct because not everyone is willing to pay attention to details. I agree that everything you have mentioned is technically correct but people need and look for simple guidelines and thumb rules from expert.
There has been a huge debate about the goal of statistical tests. Is their purpose to
(i) find the truth (the effect you noticed in your experiment and the hypothesis you propose to explain it being true or not), or
(ii) help an experimenter in making a decision what future experiments should they do to get closer to the truth.
I see this same debate re-occurring pandemic times. And I would argue that we must aim for the latter because in the end people want to know: Should I wear a mask or not? The former truth can be sought out in non-pandemic times with well-defined studies that are not under time pressure to churn out a publication.
WHO expertise failed to cut through this superficial chaos of "scientific expertise" to help people make that decision early on.
Note that, due to "researcher degrees of freedom", statistical tests are a lot more effective at stopping you from fooling yourself than they are at stopping you from fooling others. Preregistration helps with the latter problem, but there's ultimately no substitute for actually replicating the results.
Two nitpicks: an FFP2 should also work pretty well with its 94% filtration capacity. Second, I assume you're in Europe, because USA-spec N95 or N100 masks would also work. Doesn't affect the point you're making.
Reason and recent scientific evidence, however, does affect your point that nothing but the highest-rated respirators prevent contraction. The FFP2/FFP3/N95/N100s of the world prevent contraction much more effectively than lower-rated masks or respirators, but it's wrong to say that other masks don't protect against this coronavirus.
Common sense suggest that homemade masks prevent the contraction of COVID, just to a substantially lower extent than the higher-end respirators. Even before the scientific studies came out showing that homemade masks could reduce contraction, it wouldn't be dumb to wear a mask for purely selfish reasons. A bandana blocks some particles. A Chinese spec KN95 is likely better. Even if the bandana only blocks 25% of particles that could cause COVID, I'd definitely wear it if it was all I had and I had to go to the grocery store.
I agree with everything you said except about the protection thing. I would except things that are supposed to protect me from a thing to be capable of it - a bandana, a mask, or a lower-rated respirator protect me from most droplets containing the virus, but have no capability of protecting me from the virus itself. However this is, as another commenter said, probably too much technical correctness.
- If using X reduces the probability of contracting P. then X protects you from X. right?
- If a mask prevents you from touching your face and that reduces the probability of contracting the disease. Then masks do indeed protect you.
> I wouldn't want my doctor to only wear a mask.
I feel that this is a strawman.
- - -
but even if we ignore the face-touching, I don't understand how is it possible for masks to make things worse.
if we were talking about bacteria, then yes the bacteria can fester there.
but if the virus is carried by droplets, and a part of these droplets end up on the mask instead of in your nose.
then surely that would reduce the probability of being infected right?
I never said masks make things worse (with the exception of the doctor) - I think I said the opposite.
My doctor should wear something that has a filter capable of catching the virus, such as FFP3 respirator. When you breathe in, droplets get through the mask (this gets progressively worse as the mask gets wet) - and if the mask is not a FFP3, you're making a bet that none of the droplets that get through are contaminated, because the mask does not protect you from the virus, it merely protects you from some of the droplets around you; only the correct filter will protect you. The virus is around 50-100 nanometers.
It's probabilistic, like everything, but N-95 masks do protect the wearer from particles that small. The CDC purposefully lied to you so that you wouldn't stockpile masks they (understandably) wanted to use elsewhere.
>Consistent with single-fiber filtration theory, N95 and P100 respirators challenged with silver monodisperse particles showed a decrease in percentage penetration with a decrease in particle diameter down to 4 nm.
If the mask stops some droplets (which it obviously does, as it gets wet over time) and some of those droplets carry the virus, then obviously the mask protects against the virus - not 100%, but some percent (just like condoms!).
But as far as we know, the bare virus does not travel through the air, it only travels in droplets. Although there is some disagreement on how large those droplets are.
I feel like I have a wrong model of how things work.
I'm thinking that for each virus there is a chance that it will infect a cell. The higher the viral load, the higher the number of chances that you will get infected.
a lower number of droplets -> lower viral load -> less chance to be infected.
- "CDC does not recommend that people who are well wear a facemask to protect themselves from respiratory diseases, including COVID-19," the CDC says. "Facemasks should be used by people who show symptoms of COVID-19 to help prevent the spread of the disease to others."
So, March 1, CDC already said: "Facemasks should be used by people who show symptoms of COVID-19 to help prevent the spread of the disease to others."
What have we learned since? That even the people who don't show symptoms indeed spread the disease to others. So the advice was based on the false assumption, and had to be corrected.
Where the false assumption comes from? There were other infections where the infected were able to spread the disease to others only once they show symptoms.
What follows from the new knowledge? That the facemasks should be used by people who can spread COVID-19 to help prevent the spread of the disease to others. Which means: everybody.
And that is scientific process: when you learn something new, you admit to yourself and everybody else that the previous handling was based on the wrong assumption, and you adapt. You don't keep claiming that the Earth is in the non-moving center of the Universe, just because you claimed that before you learned more.
The problem is that the broad population is not only not used to adapt to the new knowledge, it's that the religions and political parties want the people to keep the same "group" identification and fix beliefs, is spite of anything.
Unfortunately, it's also true that there was an aspect of "temporary policy of what is possible." And there was a real, hard and sad reason for that: the whole western world was woefully unprepared, including not having enough masks. A lot of Asian countries were much better prepared, and had enough masks and had the policies that required them in spite of whatever was fashion in the west and had the people ready to follow the policies.
Imo, it is entirely fair to criticize CDC on its handling of this point. The asymptomatic transmission was possibility before March. It is not a shocking new possibility, it was possibility all along.
There were countries that mandated and propagated masks long long before CDC stopped claiming masks do nothing.
Wearing a mask (for the most of us not working in healthcare) prevents you from spreading the disease. It's not for protecting yourself, but for protecting others.
Since you can spread the disease even without having symptoms, and showing symptoms can take up to 15 days, then you should wear a mask, specially in closed, crowded spaces.
There is no hidden agenda, conspiracy or whatever satisfies your imagination.