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nopie  1yr ago (vinayprasadmdmph.substack.com)   Edited 1yr ago   2910 thread views

Cochrane review is out and masks have weak evidence that they are not effective

vinayprasadmdmph.substack.com

This one is against rationalists because when Scott wrote his review that masks could be effective many of us trusted it.

I don't blame Scott for failing this one because doing review of hundreds of studies is hard and one person can hardly do it. But this clearly shows that rationalist way of thinking has no special formula, they can be easily mistaken and fall by accepting general consensus just like any other person.

I was impressed when Scott did his review about masks. I trusted it because there was no other clear evidence available. Cochrane hadn't done its review yet and NICE guidelines were silent on the issue. We vaguely knew from previous studies that masks are not effective, The WHO had said so. Suddenly everyone flipped and it was not because the evidence had changed. We simply wanted to believe that masks work and we mocked those who said “no evidence that masks help”.

Even with the belief that masks work, I never wanted mask mandates. I preferred recommendations only, so that no one was penalized or prohibited entry, travel etc if one doesn't want to wear mask. Scott unwillingly had been a catalyst for governments to introduce mask mandates and all this heavy handed approach has been for nothing.

Now we are back to square one, the evidence about masks is weak and it does not support their use even in hospital settings. We can all reflect now what happened in between during these 2 or 3 years. When I realized that Scott's review is clearly insufficient as evidence, I asked some doctors if they have any better evidence that masks work. Instead of getting answer I was told not to be silly, parachutes don't need RCTs and accused me of being covid denier for nor reason. Many so-called experts were making the same mistake as Scott by looking at the issue too emotionally. It is time to get back to reality and admit that it was a mistake and we should have judged the issue with more rational mind.

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Masking is one area where a lot of people seem to have lost their minds, or at least dropped their scientific reasoning over some sort of gut feeling.

As I said in a reply, the default position is that masks do nothing until proven otherwise. We have research dating back to 1919 that suggest they do in fact do nothing. They mandated them in Spanish Flu and found no difference in mortality anywhere. There have been many pandemics since 1919 - for example the nasty Asian flu of 1958 and Hong Kong flu of 1968. Masks were never recommended to the public for any of them, because the consensus was that they did nothing. When SARS hit in the early 2000s, not only were they not recommended but you could be fined in some countries up to $100,000 for trying to claim they did in order to sell them.

This all changed in 2020 - not because of any new evidence, but because people threw away all of the research in a fit of politicisation. I mean that literally too - websites which had articles dismissing masks based on the available evidence were pulled down because they "disagreed with the current climate". Even in 2020 it was fairly trivial to look at heavily masked countries vs unmasked countries and not see any real difference. Journalists liked to pick a specific country like Czechia and claim they beat COVID with masks, and then fell silent as Czechia became one of the worst countries in Europe for COVID mortality. This pattern happened a lot - barely any articles from 2020 stood the test of time.

Up until 2021 people liked to use Asia as "proof" that masks worked. Of course that has now fallen apart since then, as South Korea has shot up the rankings (along with Singapore, Taiwan and Hong Kong). All of those countries are 99%+ masked, and South Korea is actually fascinating as they had more cases per capita in the span of 2 months than the US has had during the entire pandemic - while fully masked, and with the majority of people wearing KN94s (i.e. much better than surgical or cloth masks).

Some like to claim N95s work (not based on any actual evidence as far as I can tell). Even assuming they did, they only work if they're professionally fit-tested to ensure there are no gaps, because even a tiny gap renders it totally useless. You can't filter air if it's not going through the filter. It's not feasible for an entire population to be fit-tested (especially not once per year as is required for professionals), and it's not at all realistic for people to be able to gauge it for themselves. Not to mention that everyone would have to shave off all of their facial hair and possibly remove piercings. And again, there's no real evidence that they work against COVID anyway. The huge numbers of medical staff that were off sick with COVID despite wearing N95s suggests they do not work against it. We don't even fully understand how COVID spreads - we believe it to be airborne, but for all we know it's infecting people via their eyes.

At this point I genuinely don't know how people still believe in them. There are no longer any cherrypicked countries people can point to to say "see masks worked here! but not the other places that wore them at the same level, because reasons!". We've had lot of opportunities for comparison - England after they dropped the mask mandates vs Scotland which kept enforcing them (Scotland performed worse), US counties which re-adopted masking while their neighbours didn't such as Alameda county vs Contra Costa (no difference), German provinces with mandated N95s vs the other provinces with surgical or cloth (no difference).

The claims have decayed from the lofty "if 50-80% of people wore masks, the pandemic would be over!" in summer 2020, to the current "they might make a slight difference, but don't trust the studies - trust my gut". The public-facing experts who pushed masks so strongly have turned out to be mostly quacks - people who suggested you wear panty liners on your face as a filter. People who thought scarves and t-shirts would be a suitable substitute. How many videos are there of politicians donning the mask for the cameras, and then removing it when the cameras were off? Even someone like Fauci didn't wear one at the airport. These people didn't actually believe in masks. It was a political policy, not a medical policy.

They mandated them in Spanish Flu and found no difference in mortality anywhere

I mean back in that era essentially the best they could do was hessian sackcloth.

I agree that masks are likely of essentially zero value, and if they were going to be of value it'd be of the 'If you follow all 58 laws of medical compliance, never breathe too hard or adjust your mask whatsoever you might receive a 1% resistance to a disease of your choice' which is beyond implausible. The whole adoption during COVID was far more about team membership than anything.

This is probably because population-level masking is more of a political than an evidence-based issue- values play a big role. And in any political issue, no matter how much people claim to be objective, factors such as "what the other side did" will always matter in judging the data, and in judging the proponents of particular interpretations of that data.

For this reason I find both sides of the flip-out to be lacking in self awareness. These kinds of conversations often begin with a friendly calm and end with both sides betraying each other without admitting to having done so, because somewhere along the line instinct and fuzzy memories took over without being noticed.

Imagine - New large RCT: Emergency medical treatment in rural Nigeria largely ineffective. Okay. But the potential causes are 'long distances so it takes too long to arrive at emergencies, poor training of medical personnel, patients and practitioners hold non-western medical beliefs, lack of resources to purchase good medical technology'. Not 'emergency medicine is bad'.

So, from the meta analysis:

We pooled trials comparing N95/P2 respirators with medical/surgical masks (four in healthcare settings and one in a household setting). We are very uncertain on the effects of N95/P2 respirators compared with medical/surgical masks on the outcome of clinical respiratory illness (RR 0.70, 95% CI 0.45 to 1.10; 3 trials, 7779 participants; very low‐certainty evidence). N95/P2 respirators compared with medical/surgical masks may be effective for ILI (RR 0.82, 95% CI 0.66 to 1.03; 5 trials, 8407 participants; low‐certainty evidence). Evidence is limited by imprecision and heterogeneity for these subjective outcomes. The use of a N95/P2 respirators compared to medical/surgical masks probably makes little or no difference for the objective and more precise outcome of laboratory‐confirmed influenza infection (RR 1.10, 95% CI 0.90 to 1.34; 5 trials, 8407 participants; moderate‐certainty evidence). Restricting pooling to healthcare workers made no difference to the overall findings. Harms were poorly measured and reported, but discomfort wearing medical/surgical masks or N95/P2 respirators was mentioned in several studies (very low‐certainty evidence). .

This is entirely consistent with universal proper use of N95s significantly reducing disese, and surgical/cloth masks not. I'm not sure how to square that with the substack post's comments on N95s, which was "The section on N95 masks was also devastating. [excerpt] Obviously, unlike the types of studies that the CDC likes— hairdresser anecdotes— randomized trials are the best way to separate an intervention from the habits of someone who embraces them."

I wouldn't say the review is good evidence either way on N95s - and the higher quality evidence is more negative than the lower quality evidence - but I don't think the above paragraph is compatible with "devastating". The review notes "relatively low adherence with the interventions during the studies" - it's almost obvious that, for very transmissible diseases, poor adherence to interventions (say, only wearing the mask 75% of the time you're around other people) for a quickly spreading disease might not do much when good adherence would - like, r0 4 -> r0 2, doesn't end up mattering. Of course, that poor adherence is the adherence a general mask nudge / mandate would get, making those particular interventions not useful, but other interventions are possible.

If a random person read the substack, they'd walk away thinking "wow, masks are useless for respiratory diseases". But this isn't the conclusion I come to when reading the abstract - it seems likely surgical masks don't work, and unclear on N95s. Combine that with the 'low adherence', and I continue to believe that 'wearing N95s rigorously probably reduces risk of respiratory illnesses' and 'rigorously wearing N95s may have been a good move during the pandemic if you're old/immunocompromised/etc'. The politics seems to be pushing people away from stuff like that - we're showing how bad the libs are! masks bad mandates bad!

And there's a big difference between 'masks are bad, mandates are bad, this was all a mistake' and 'ineffective implementation of mask mandates was the problem, if N95s were Warp Speeded and given out for free a lot of deaths could be reduced'. The latter is ... arguable, actually - imagine a case where N95s were mandated/heavily encouraged specifically for vulnerable populations (old, immunocompromised, other health conditions), along with early studies making sure they were useful & how to use them effectively, without lockdowns or mask mandates for most.

I don't think that study saying "there is a need for better studies" is biased or misleading, as the substack seems to imply. That's usually true. As the study says, "The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions", which also seems true. Just because it's a cochrane review doesn't make it perfect or conclusive. It does mean there's a good chance the result useful, but that's different.

Also, I'd be interested in more 'interesting meta-analysis results' posted here - good post imo just because of that, even if it's only posted because of the politics.

From the meta analysis:

Our findings with respect to hand hygiene should be considered generally relevant to all viral respiratory infections, given the diverse populations where transmission of viral respiratory infections occurs. The participants were adults, children and families, and multiple congregation settings including schools, childcare centres, homes, and offices. Most respiratory viruses, including the pandemic SARS‐CoV‐2, are considered to be predominantly spread via respiratory particles of varying size or contact routes, or both (WHO 2020c). Data from studies of SARS‐CoV‐2 contamination of the environment based on the presence of viral ribonucleic acid and infectious virus suggest significant fomite contamination (Lin 2022; Onakpoya 2022b; Ong 2020; Wu 2020). Hand hygiene would be expected to be beneficial in reducing the spread of SARS‐CoV‐2 similar to other beta coronaviruses (SARS‐CoV‐1, Middle East respiratory syndrome (MERS), and human coronaviruses), which are very susceptible to the concentrations of alcohol commonly found in most hand‐sanitiser preparations (Rabenau 2005; WHO 2020c). Support for this effect is the finding that poor hand hygiene, despite the use of full personal protective equipment (PPE), was independently associated with an increased risk of SARS‐CoV‐2 transmission to healthcare workers in a retrospective cohort study in Wuhan, China in both a high‐risk and low‐risk clinical unit for patients infected with COVID‐19 (Ran 2020). The practice of hand hygiene appears to have a consistent effect in all settings, and should be an essential component of other interventions.

... whoa, what? Fomites matter for COVID? I distinctly remember "handwashing for COVID" being something the health authorities recommended early on and were wrong about, and a consensus of 'handwashing doesn't matter, masks do'. Not sure what to do with that paragraph.

Routine long‐term implementation of some of the interventions covered in this review may be problematic, particularly maintaining strict hygiene and barrier routines for long periods of time. This would probably only be feasible in highly motivated environments, such as hospitals. Many of the trial authors commented on the major logistical burdens that barrier routines imposed at the community level. However, the threat of a looming epidemic may provide stimulus for their inception.

Exactly! Again, imagine challenge trials on masks, handwashing very early in the pandemic, with results implemented in nursing homes and hospitals.

Meanwhile in the substack, from the top two comments:

Its that public health officials should never, ever, ever, ever, ever, be given the keys to society again, and that individual liberties need to be fortified against such intrusions in the future because THEY WILL KEEP HAPPENING otherwise. Public health - when it has NO POWER - only has truth. The lies are hand in hand with the power

The follow-on pieces are clear. We need to dismantle, permanently, the current public health apparatus and rebuild it from scratch using some other paradigm. It has been an abject failure in every way. It has shown itself inimical to public health and, short reconstitution, will never be a trusted modality again...and it needs to be.

The first one is weirdly moldbuggian, but ... lol. It's not nearly that bad, and even if it was "LIES. NEVER. FAILURE IN EVERY WAY" is not a useful response.

Combine that with the 'low adherence', and I continue to believe that 'wearing N95s rigorously probably reduces risk of respiratory illnesses' and 'rigorously wearing N95s may have been a good move during the pandemic if you're old/immunocompromised/etc'

The default scientific position is that they do nothing until proven otherwise. You can believe they work if you want, but there is no evidence that they do for something like COVID so it is very much a belief and not an evidence-based claim. Low adherence might be a factor in RCTs, but the majority of people in places like South Korea wear KF94s (with 99.9% of the population masked in public in some form) and they had more cases per capita in the span of two months than the US has had during the entire pandemic.

I don't understand why supposed "rationalists" cling to something with no evidence like this. Why do you think they weren't recommended prior to COVID? Masks are not a new invention. Hell, you could be fined $100,000 for claiming they would protect people from SARS because people knew how irresponsible it was to say that.

Rationalist does not mean 'you must assemble your beliefs from meta-analyses'. Meta-analyses are wrong sometimes.

but the majority of people in places like South Korea wear KF94s (with 99.9% of the population masked in public in some form) and they had more cases per capita in the span of two months than the US has had during the entire pandemic.

99.9% is too high, and anyway if 50% of people weir KF94s in public but not at home, and kf94s are 100% effective, the cloth masks still do not work, so the cloth half instantly gets it and spreads it to the other half. There is also a difference between 'properly wearing n95s significantly reduce your risk of getting an airborne disease' and 'n95s are enough to prevent a pandemic'.

Why do you think they weren't recommended prior to COVID

There was a whole dance about how the mainstream took too long to recognize covid was airborne, and therefore were wrong and stupid.

It should be uncontroversial that Koreans are much much more likely to wear plausibly effective K-94/N-95 masks than Americans though; which being the case means that the fact that COVID was able to spread way faster there than at any point in the US bears significant explaining?

99.9% is probably closer to the truth than 99%. Even in Thailand (where I'm based) for most of the pandemic you saw virtually no one unmasked, even outside. The argument that not enough people wore them does not apply in Asia.

N95s might work if you have it professionally fitted, but given the number of healthcare workers that ended up catching COVID at work I doubt they're that effective either. I think we fundamentally don't understand how COVID spreads.

Our best guess is that COVID is essentially airborne, but being airborne is precisely why masks don't work. The aerosol just leaks out of any gaps between the mask and the face... or with cloth masks, probably directly through the mask itself. If COVID was spread by large droplets, like people coughing or sneezing on each other, then yes masks might have been effective. But given that there's no difference between places that wore them and places that didn't, it's pretty reasonable to say that they are not getting to the root of the problem.

Personally I think it's airborne so easily leaking out of masks, and that it's also infecting people via their eyes as much as their nose/mouth

Even if 99.9% were wearing cloth masks, cloth masks do literally nothing on a population basis!

In Thailand I'd say it's about 60% surgical mask, 40% KF94s or similar. I think Korea's ratio is the other way around

Rationality is actually about understanding the hierarchy of evidence strength. Yes, meta-analyses can be wrong too, but in this case Cochrane report is pretty solid. Even though it is not definitive, it makes no sense to reject it and value some anecdotal cases or even lab based evidence as higher evidence.

Using that logic, do you think handwashing prevents covid? From the review:

SARS‐CoV‐2 [is] considered to be predominantly spread via respiratory particles of varying size or contact routes, or both (WHO 2020c). Data from studies of SARS‐CoV‐2 contamination of the environment based on the presence of viral ribonucleic acid and infectious virus suggest significant fomite contamination (Lin 2022; Onakpoya 2022b; Ong 2020; Wu 2020). Hand hygiene would be expected to be beneficial in reducing the spread of SARS‐CoV‐2 similar to other beta coronaviruses (SARS‐CoV‐1, Middle East respiratory syndrome (MERS), and human coronaviruses), which are very susceptible to the concentrations of alcohol commonly found in most hand‐sanitiser preparations (Rabenau 2005; WHO 2020c). Support for this effect is the finding that poor hand hygiene, despite the use of full personal protective equipment (PPE), was independently associated with an increased risk of SARS‐CoV‐2 transmission to healthcare workers in a retrospective cohort study in Wuhan, China in both a high‐risk and low‐risk clinical unit for patients infected with COVID‐19 (Ran 2020). The practice of hand hygiene appears to have a consistent effect in all settings, and should be an essential component of other interventions.

The general overview states: Pooled data showed that hand hygiene may be beneficial with an 11% relative reduction of respiratory illness (RR 0.89, 95% CI 0.83 to 0.94; low‐certainty evidence), but with high heterogeneity.

Covid as such is basically over now but respiratory illnesses remain. 11% is not much but it is at least something.

Just before seeing this post, I saw an article on social media arguing it was misleading: The Conversation: "Yes, masks reduce the risk of spreading COVID, despite a review saying they don’t". The summary of that article is that the review finds weak effects because it mixes together too many things that you would expect to have weak/no effect:

  • "mask" includes cloth/surgical masks (as opposed to [K]N95+ or equivalent masks) that we don't expect to work except maybe as source control.

  • Related, none of the studies look at masks as source control. i.e., they only study individuals wearing masks, not groups.

  • Most of the studies only had people wear masks in "high-risk" situations (i.e. around known-infected individuals) as opposed to, say, all the time while at work. Any consideration of the claimed mechanism of airborne transmission often from asymptomatic cases would lead you to expect that to not work, especially where "work" means medical settings where you have higher expectation of infected people around.

  • Bonus: none of the studies compare mask wearing to not masking wearing, only being advised to wear masks to not being advised to wear masks.

The articles claims if you pare down to only the studies looking at "Does wearing N95s all the time reduce COVID-19 transmission?" the answer is in fact "yes", the opposite of the headline.

Isn't "properly fitted N95s work" just another way of saying "mask mandates don't work"?

I thought the topic was "do masks work?" not "do mask mandates work?". These are very different questions, and can be broken down further with questions like "do N95 masks worn by untrained people work?" and "do fit-tested N95 masks work?", without even delving into the details of how we want to define "work", presumably some measure of reducing the incidence of COVID-19 in the mask wearers, although looking at reducing the incidence of COVID-19 in people around the mask wearers is also an interesting question.

The summary of the study that I referenced suggests the study answered the question of "does having masks vaguely nearby that you wear inconsistently reduce the incidence of COVID-19 in mask wearers?" and got the utterly unsurprising answer of "no". Maybe that's a realistic view of what behavior under mask mandates looks like, but that information doesn't really give us any hints on the answers to questions like "does training our medical personnel and requiring them to wear fit-tested N95s at all times reduce the transmission of COVID-19 in our medical facility?" or "does an individual choosing to wear an N95 while on transit / in airports reduce the chance they'll get COVID-19?".

The fact that many people are unable to take prescription drugs frequently or consistently enough for them to be effective at treating their illnesses is not usually considered an argument against telling them to do so.

What happened is more like the government mandated an ineffective drug, censored anyone for pointing out it was ineffective, and once evidence came out that the drug doesn't work, people started defending the policy by saying there's a completely different drug that the government could have mandated, which would be effective (but it needs to be taken in precise 3 hour 37 minute intervals, and being off by one minute renders the drug ineffective).

Do you think I or 'meh' are defending the policy of mask mandates?

I am defending the policy of mask mandates, in the abstract, if it includes "do rapid and large challenge trials of N95s + ways of ensuring proper use in early 2020". I'm not defending "tell everyone to wear cloth masks", which doesn't seem to have done anything, and which is the meaning you are using.

If it was found in RCT trials that the drug does not treat the illness in the treatment group (whatever the reason), it would not get approved.

Most of the reason for that is drugs are expensive, use of a drug is based on belief it works and as such it crowds out other useful treatments, and have high rates of side effects. There's a reason a pharmaceutical to treat a disease requires rigorous testing before FDA approval but 'Ngoko Bean Extract For Psoriasis' doesn't if Ngoko beans are edible. This makes 'not being approved' much less strong as a reason to not wear masks even though, again, the mask mandate didn't do much.

The point here is that when someone has psoriasis why does he need to get the approved medicine if Ngoko bean bean extract could be used instead without prescription? The reality is that we don't know if Ngoko bean extract (and thousands of other remedies offered by snake oil peddlers) works for psoriasis. Obtaining this information can be costly and I can see why no one wants to study Ngoko beans if they cannot be patented.

However, psoriasis is mostly auto-immune disease and if topical treatments do not work, specific monoclonal antibodies can be tried. They are not cheap but that's because the technology to make them is quite complicated.

Yeah, we don't know if ngoko beans work, but we do know they don't hurt, so "using them when it isn't approved" isn't as bad.

No, we don't know if ngoko bean extract don't cause harm. They could easily make psoriasis actually worse.

It is unbelievable today but merely 50 years ago cigarettes were recommended for treating asthma and were sold by pharmacists. Today we know that cigarette smoke actually harm airways and make asthma attacks worse.

The likelihood that ngoko bean extract (ngoko beans don't exist, so let's go with black bean extract) harms you is much much lower than the probability some random normal pharmaceutical like ivermectin harms you, which in turn is much lower than the probability a random never-approved-for-any-indication pharmaceutical harms you. This is because lots of people at black beans as food, already. And masks are less likely to hurt you than black bean extract. This is why wearing a mask without RCTs isn't the same as taking a random pill without RCts.

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Consider this analogy: laws mandating wearing of seatbelts in cars don't prevent 100% of automotive fatalities. Sometimes this is because people aren't wearing their seatbelts properly. Sometimes this is because people just ignore the law and don't wear them. Sometimes this is because the specific type of accident caused trauma that seatbelts can't mitigate.

Would you therefore conclude "seatbelt mandates don't work"? Would you think it reasonable for the highway department (or whomever) to stop encouraging the wearing of seatbelts because they're not 100% effective?

Consider this analogy: laws mandating wearing of seatbelts in cars don't prevent 100% of automotive fatalities. Sometimes this is because people aren't wearing their seatbelts properly.

This analogy is inaccurate in the context of the conversation. A more accurate analogy would be one where the mandated seatbelts are made out of toilet paper, and break at the slightest stress.

An N95 mandate would something closer to "seatbelts, but people don't wear them properly", but that's not the mandate we got, and it's not even clear it's realistic to get a significant amount of the population to wear them properly, unlike seatbelts.

We haven't done RCTs with seatbelts, but I can easily imagine them being very positive in favour of seatbelts even in case of some occasional non-adherence in the intervention group.

We haven't done RCTs with seatbelts

I know a bunch of crash test dummies that would like to have a word with you.

We now have talking test dummies :D

Yes! Mask mandates, as implemented, clearly didn't work. But this does not mean masks, if used properly, don't work - yet that's how everyone is interpreting it, including the other reply to your comment.

I don't think this is how he's talking about it, but he can defend himself.

What's the point of discussing some abstract perfect usage of a mask type most people didn't even have, given the policies that were implemented and the censorship of dissent? When people say "masks don't work", they clearly mean the masks they were forced to wear.

the point of discussing mask usage in genereal is to ... figure out policy for the future? Or just figure out personal risk tolerance from the future? Concretely - should my/your elderly parents occasionally wear N95s in e.g. airports, to reduce general disease risk? From my longer comment:

The latter is ... arguable, actually - imagine a case where N95s were mandated/heavily encouraged specifically for vulnerable populations (old, immunocompromised, other health conditions), along with early studies making sure they were useful & how to use them effectively, without lockdowns or mask mandates for most.

And from the review itself:

Routine long‐term implementation of some of the interventions covered in this review may be problematic, particularly maintaining strict hygiene and barrier routines for long periods of time. This would probably only be feasible in highly motivated environments, such as hospitals. Many of the trial authors commented on the major logistical burdens that barrier routines imposed at the community level. However, the threat of a looming epidemic may provide stimulus for their inception.

When people say "masks don't work", they clearly mean the masks they were forced to wear.

I think when people say "masks don't work", they mean "masks don't work". See the OP substack citing the evidence against N95s as "devastating".

You cannot separate “telling people to wear masks work” from “wearing masks work” in the intervention. It is the real life we are talking about.

The argument that maybe the results would be better if we apply efforts to improve the compliance is a real one and was raised by the Cochrane group reviewers. Their answer was that no one has studied it, so we don't know and cannot claim that it would have helped.

I was just learning about different contraceptive methods. Their reported results of effectiveness are not some best case values but real life results from studies. https://en.wikipedia.org/wiki/Pearl_Index Even that is being criticised that in studies people get better counselling and training and may not represent the real life values. I find interesting that fertility rhythm method has very high theoretical effectiveness (slightly worse than condoms – https://en.wikipedia.org/wiki/Comparison_of_birth_control_methods) and yet it is heavily criticized by all experts in the field. It is always more easier to take a pill than measure temperature daily plus all other behavioural aspects.

Some argue that it still makes sense for their elderly relative to wear mask to protect themselves. Maybe, but I don't know your elderly relative. The statistical chances are that they are as much non-compliant as any other member of the population. Telling all hundred or thousand of them (how many readers do we have?) to wear a mask will statistically yield the same result as in those studies.

I find interesting that fertility rhythm method has very high theoretical effectiveness (slightly worse than condoms – https://en.wikipedia.org/wiki/Comparison_of_birth_control_methods) and yet it is heavily criticized by all experts in the field.

Interesting analogy -- 'withdrawal' might be a good parallel with masking, in that it actually works not bad if you can pull it off (out) but field results are poor due to, uh, implementation difficulties.

For this reason people are usually told "withdrawal is like 99% ineffective" -- which isn't really true, but serves the public health goal.

Leads one to speculate that the public health goal is quite different in the case of masking.

You cannot separate “telling people to wear masks work” from “wearing masks work” in the intervention. It is the real life we are talking about.

Then you just go back to the seat belt problem. Seat belts existed since the early 1960s but usage rates were abysmal for 25 years. Someone studying the effect of seat belts in 1985 would have found their efficacy lacking for the simple reason that few people used them. Seat belts had been required equipment in cars for some time but given that so few people were using them so long after their introduction, the Federal government could have been forgiven for scrapping the requirement altogether as ineffective. Instead, this is around the time state governments started requiring seat belt use among all front seat occupants. As the 1980s became the 1990s and more states started adopting such laws, auto fatalities, which had been more or less stagnant for decades, halved between the late 1980s and the present. Part of the problem could be that in a lot of places these so-called "mask mandates" were so inconsistently enforced and widely ignored that the actual effect was that of no mandate whatsoever, and that the real solution is stricter enforcement. This isn't necessarily a policy I would advocate for, but simply stating noncompliance is proof that the underlying implication is wrong is disingenuous, to say the least.

Most cars didn't have seatbelts then. Some of those cars are still running and it is legal to drive them without seatbelts.

RCT could be easily made by manufacturing a car with two models that are different only by presence of a seatbelt and randomly shipping to different dealers. If the car had a seatbelt, a dealer is obliged to explain a buyer how to use it properly. The car could have a mechanism installed that warns if the seatbelt is not in use and the dealer warns that defeating this measure will void the warranty. The compliance rate would be at least 50%. Then you just collect statistics from road accidents and related injuries. I am sure very soon this experiment would be stopped by an ethics committee because the seatbelt group would have huge difference that further studies would be unethical.

Maybe people who study road safety used a similar setup by comparing one model with a seatbelt to a different model without a seatbelt. It has some bias as assignment is not random and both groups can be different, for example, one model can be chosen by more careful drivers etc. It is very hard to control for all these factors afterwards. But even then they saw such a massive difference in injuries that could be explained only by seatbelt use, that it was made mandatory. It is easy to make mandatory rules in driving because most things in driving are mandatory, you have to stop at red light etc.

But the absence of RCTs and irrefutable evidence could be a minus because it was harder to explain people why seatbelts are protective. Many people said that seatbelts will protect you in minor accidents but in major crashes they would make you more likely to die. That's why we need a good evidence that seatbelts have a total protective effect from deaths although they won't protect in all possible cases. It would have improved adherence even without policing.

Someone studying the effect of seat belts in 1985 would have found their efficacy lacking for the simple reason that few people used them.

Nope. They'd find typical usage would (on average) result in people surviving the car crashes, and the non-usage in dying. We don't have anything like that justifying even an N95 mandate.

No, his claim is if you studied P(death | accident, car with seat belt) / P(death | accident) you wouldn't find an effect unless the sample size was massive because P(wears seat belt| car with seat belt) is very low, so P(death | accident, car with seat belt) = .1 * P(death | accident, wearing seat belt) + .9 * P(death | accident) which is .92 * P(death | accident), even if seat belts reduce crash risk by 80%!

We don't, but that's not what the study looked at.

The point is that we're dealing with a Motte and Bailey argument here,

Yes. The bailey is "of course masks work, you're banned for spreading misinformation", and the motte is "of course properly fitted masks, of a type that no one wore, work".

It's especially bizarre to see given that the same people are claiming to be (legitimately, IMO) upset at Fauci and Co. for misrepresenting/misinterpreting/misusing science and statistics to argue for mask mandates.

How is it bizarre? I maintain that it's obvious when people say "masks don't work" they meant the masks they were actually forced to wear. What are they misrepresenting? How is it not the pro-maskers who are not misusing the science instead?

Standard pattern of Motte-versus-Motte warfare: my motte is to deny you your bailey, and my bailey is to also deny you your motte (and, automatically, your position is symmetrical).

Sound medieval warfare tactics.

"you're banned for spreading misinformation" is downplaying things. In the real world, where mask mandates were sometimes enforced, the bailey sometimes became "of course masks work, and the police will beat the shit out of you if you disagree."

I've stalked people since the reddit site and remember the arguments they used to make. There were plenty of people making those arguments "here" in 2021, and there needs to be some process to address old arguments without allowing a temporal motte and bailey.

I don't recall anyone on /r/themotte saying 'you should be banned for misinformation if you say masks don't work'. My old comments were of the form 'should have had RCTs to figure out how to make masks that work early'.

Why should we limit ourselves to the conversation that is happening here?

but lots of people are absolutely making the M&B argument I'm citing.

Again, they can defend themselves, but I think you're misinterpreting people.

More comments

Exactly this. Don't even try to think seriously about articles that claim that masks work despite evidence that says they don't. It is a big fail for rationalists to even think in this way.

A common dispute towards the results of this study on the basis that the evidence-base is weak (true) and therefore you should wear a mask anyway (false). Usually on the basis that masks either work or they don't, and if they do, then that's great. But there's a hidden assumption in this claim. If the result is inconclusive, then there's no reason, a priori, to assume that wearing a mask is either neutral or positive. It might be negative instead, increasing your chance of catching covid. The evidence is just as compatible with this outcome as it is with it reducing your chance of catching covid.

I do blame Scott for failing this one because you don't need to review hundreds of studies to figure it out. There's not hundreds of studies to even look at. Cynically, I think whether he looked at studies or not was irrelevant, because he was never going to contradict the regime.

Given that there's no evidence in favour of masking, and there has always been no evidence in favour of masking, we are left with a conundrum. Why did governments do that u-turn in 2020? Regardless the legitimacy of many regimes now rests upon this... Admittedly, however, masking is just a rounding error compared to the sum of fraudulent restrictions imposed by the majority of regimes.

I've always wondered if they realized:

  1. Lockdowns aren't going to get rid of COVID

  2. We've turned some decent percentage of the population paranoid

  3. We need that population to start doing things again or we kill the economy

  4. Masks work! Just wear a mask and you are safe to go around making and consuming Economics inputs and outputs!

But maybe that is too conspiratorial...it really was a huge switch though. The stated reason was that they realized the amount of presymptomatic/asymptomatic spread, but lots of illnesses have huge periods of presymptomatic spread (Influenza and RSV, notably), so not sure why that would have resulted in a change.

That is both the correct amount of conspiratorial, but far too competent. What actually happened was:

  1. Lockdowns aren't going to get rid of COVID

  2. We've turned some decent percentage of the population paranoid

  3. We must do something

  4. Masks are something

Never attribute to incompetence what you can attribute to principal agent problems. High level politicians are incredibly competent... at politicking. There's a whole host of complicated social skills involved in phrasing your words the right way, appealing to a core of voters in your party, playing nice with other politicians and the political party backing you, fundraising, and deflecting criticisms of incompetence. And the people who actually get elected to top positions are nonrandomly the best of the best at these things, or they get quickly replaced by someone who is better.

Object level issues like "what policies will minimize both the death rate and economic harms of COVID" are secondary to things like "what policies will make my constituents vote for me again?" or "what policies does my political party that I am beholden to want me to support?" There's a nonzero correlation, actual good policies are slightly more likely to be visually appealing and/or get bipartisan support, but the politics is the actual target they are optimizing for. And from that perspective, they did an excellent job: the majority of politicians who supported mask mandates have been re-elected, and those who weren't probably lost for unrelated reasons that wouldn't have changed if they had promoted better policies. If they appear incompetent, it's because the metric you're using to measure success isn't the same one they're using.

The problem with “let's try masks because they might help” is that there are countless potential interventions without any benefit. For example, you could regulate humidity in buildings because the belief is that dry air favours viral adhesion to airways. It would be moderately expensive but the evidence that it would help with anything is zero.

Most of low-hanging fruit in public health is already picked and any progress towards better medicines is painstakingly slow and requires good and thorough evidence. It is ok to be sceptical of any media reports about new game-changing drugs or interventions. Only very few of them will be finally approved and even fewer of them will have good effectiveness.

Cochrane's own conclusion says:

The high risk of bias in the trials, variation in outcome measurement, and relatively low adherence with the interventions during the studies hampers drawing firm conclusions.

When you look at the included studies, it's not hard to see why. For one, many of these studies pre-date COVID and focus on ILI. In addition, the ones that I've looked at so far in their summary table are not measuring the effectiveness of masks. They're measuring the effectiveness of trying to get people to wear masks, if they aren't already. For example, the second study listed, Alfelali 2020, notes that the test group had about 25% "daily" mask use and 13% in the control group (it was also a study of ILI, with data gathered from 2013 to 2016). On the flip side, we have MacIntyre 2015 reporting over 50% adherence for both cloth and medical masks (which was on healthcare workers, clearly a different population). Given the obvious issues with both noncompliance and heterogeneity, it's not exactly surprising that they got a null result. It looks to me like only 2 of the included 12 studies were even specific to COVID.

From the point of view of a policymaker, this (arguably) makes sense, although you would still prefer to have separate studies of how people respond to wearing masks, and then how effective they are if you wear them. Both of those things are likely to change based on location and population. From an individual point of view, you should care much more about how effective masks are if you wear them consistently and interact with other people wearing them.

The linked blog post is greatly exaggerating the strength of this evidence, and clearly is trying to push a political agenda by downplaying these limitations and ignoring any nuance.

The linked blog post is greatly exaggerating the strength of this evidence, and clearly is trying to push a political agenda by downplaying these limitations and ignoring any nuance.

There was once I time I believed there are people who aren't doing that. Then there was a time I could at least pretend. We're so far past that point it's not even funny.

Can you show how what they're doing is worse then what the people who pushed through mask mandates did? Otherwise there's nothing interesting about that sentence.

Can you show how what they're doing is worse then what the people who pushed through mask mandates did?

No, such a task is impossible. "People who pushed through mask mandates" is an enormous and varied group. It's almost certainly the case that some of them insisted the evidence is overwhelming, while others were more sanguine.

Otherwise there's nothing interesting about that sentence.

The link posted here wasn't a link to someone claiming that masks are definitely foolproof and should be enforced during COVID outbreaks. If someone makes that post with flimsy evidence (and I see it) I'll call them out too. I oppose bad arguments, regardless of the conclusion.

So you were passionately arguing against mask mandates when they were being pushed?

What does that have to do with anything? Do you actually care about the evidence, or are you just looking for gotchas?

Well, it would show that you oppose bad arguments regardless of conclusions.

Do you actually care about the evidence

Sure, I'd love to see evidence that would justify the actually implemented policies, and the censorship of dissent.

I did oppose mask mandates, but I could also just be saying that now because this entire forum isn't that old.

Anyway, I don't get the sense you're acting in good faith, so this is probably where I bow out of this conversation.

It seems hard to believe that properly fitted N95s don't work considering that they are approved PPE for ebola which is somewhat higher stakes than Covid. Perhaps people do not wear them right, whatever that means?

considering that they are approved PPE for ebola

I thought ebola spreads through direct fluid contact. Which also includes respirated droplets assuming you stand very close to an infected person. But, based on my very non-epidemiologist understanding, that's not comparable to respiratory viruses.

People can't even wear condoms right, and if we counted sandwich bags held with a rubber band as condoms the statistics would look even worse.

(only allowable facial hair is mustache, as one factor)

Good to see that "toothbrush mustache" is still OK! Fans of, uh, Charlie Chaplin will be most relieved.

I feel the need to point out that that style of mustache was in fact adopted by German soldiers in WWI to fit under a gas mask.

That's the joke...

Missed opportunity to keep the image but label it "Hitler" and put a big red 'X' on it!

Ed: plus "Careful not to commit genocide" underneath, for a chef's kiss

It is possible that "people do not wear them right". I've seen many extremely smart people wear masks in very inconsistent and random manner. I attribute it to psychological mechanisms - if they feel unsafe (consciously or unconsciously) for some reason in the environment, they put on the mask, if they feel safe, they remove it. But whatever the deal is, saying "masks help when theoretical perfect human wear them in theoretical perfect manner, otherwise they don't" is just saying "masks don't help".

Ebola spreads primarily through bodily fluids like blood and faeces. Quite different from covid.

Okay, but they are also approved PPE for TB. https://www.cdc.gov/niosh/docs/96-102/pdfs/96-102.pdf?id=10.26616/NIOSHPUB96102

Then we should probably consider that, absent evidence that it works for TB, it probably doesn't work for TB and the guidelines are wrong.

Maybe masks filter things efficiently (just for the sake of argument) but it doesn't matter in practice because people cannot wear them 24 hours without stop and will get exposed to unfiltered air at some time. If the end result is that mask wearers get respiratory infections at almost the same rate as the rest, what is the point?

Also we are supposed to see the big picture, not just some technical point. Mask mandates would be wrong even if they were effective.

They presumably work on public transport, and airplanes.

Also we are supposed to see the big picture, not just some technical point. Mask mandates would be wrong even if they were effective.

Well then who cares what the cochrane review says?

The Cochrane report came out just now but the policy for mask mandates was made without it. The policy was wrong not because in hindsight we have the report but because it encroached on our freedoms without sufficient evidence that it was necessary.

So why did you post the report if it has nothing to do with the argument?

Because we can all learn from the mistakes made?

This is just to show what mistake rationalists made about masks. Some still are trying to claim that “masks work despite the evidence that they don't” whatever that is supposed to mean.

Some may use Bayesian method (my favourite). In my view, Cochrane report strongly decreases the odds. Whatever way you go, the threshold for mask mandates was never reached.

I think it's still important. It's wrong to say "we will force you to do this thing for your own good", but it's even more wrong - some would say evil - if the "good" actually isn't good at all.

Sometime if you get the chance, I highly recommend fit testing an N95, they're quite hard to get right without a good amount of training. The test is kind of goofy, after the mask is applied, they put a big hood over the head and shoulders and puff saccharine in if you taste sweet it's a fail.

Are respirators better? I wore a respirator for welding and when I held my hands over the filters I couldn't breathe at all so I think the fit was pretty good. Seems like that's what you would want if you're dealing with something that's actually dangerous like Ebola.

Wikipedia is pretty convinced that N95 masks are technically "respirators" as well, but, yes, one advantage of P100-style respirators is that they are easier to fit correctly.

Not a great example given that South Korea is getting close to having the most COVID cases per capita in the world

Singapore, Hong Kong and Taiwan are all in the top 25 too

Wear what you want. The issue is demanding other people wear them.

Cultural differences; West = individualistic and libertarian, East = collectivist and conformist

And? Are Asians infallible? Many South Koreans believe leaving a fan on overnight will cause you to suffocate. Should we trust them on that?

Everyone in Asia eats with chopsticks but if the CDC tries to take my fork away I'm still going to be pissed.

In Asia right now.

I can confirm that your summary is oversimplified and very incorrect.

I just saw something on this and started writing a top level post myself. Might as well consolidate to your thread, seeing as you got in first.

Here is the review of many studies: https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6/full

We included 12 trials (10 cluster‐RCTs) comparing medical/surgical masks versus no masks to prevent the spread of viral respiratory illness (two trials with healthcare workers and 10 in the community). Wearing masks in the community probably makes little or no difference to the outcome of influenza‐like illness (ILI)/COVID‐19 like illness compared to not wearing masks (risk ratio (RR) 0.95, 95% confidence interval (CI) 0.84 to 1.09; 9 trials, 276,917 participants; moderate‐certainty evidence. Wearing masks in the community probably makes little or no difference to the outcome of laboratory‐confirmed influenza/SARS‐CoV‐2 compared to not wearing masks (RR 1.01, 95% CI 0.72 to 1.42; 6 trials, 13,919 participants; moderate‐certainty evidence).

Here's a substack interview where the lead author talks about the report probably being suppressed back when they first finished it in late 2020. They were made to water down the conclusions as well:

https://maryannedemasi.substack.com/p/exclusive-lead-author-of-new-cochrane

I'm quite surprised because it seemed logical that masks would work. Why do doctors wear them if they don't work? In the past I've argued against the competence of the health authorities on the basis that they backflipped from dismissing masks to endorsing them. I thought at the time they made an error in starting off being anti-mask, since that goes against the logic of airborne diseases. But if they made an error in the other direction, that masks don't actually work and then suppressed it for years... That's much worse!

Fundamentally, if we don't have the skills and capability to quickly test and determine correctness or incorrectness of these things, we will not survive this century. We cannot expect just to have easy challenges forever. AI, more advanced bioweapons, nano... things are going to get harder not easier. We must get things done correctly, regardless of whether it makes people uncomfortable. Could we not have gotten some prisoners and deliberately infected them with COVID, just to see how effective masks are in various scenarios? Nobody had any qualms about doing roughly the same thing to the elderly in New York!

https://www.propublica.org/article/andrew-cuomos-report-on-controversial-nursing-home-policy-for-covid-patients-prompts-more-controversy

On March 25, Cuomo, saying he feared that an onslaught of COVID victims would overwhelm hospitals, issued an order that required nursing homes to accept COVID-19 patients being discharged from hospitals, so long as they were “medically stable.” Under the policy, the nursing homes receiving the patients were barred from testing the patients to see if they might still be contagious.

I maintain that there should be extremely high stakes for such failures. Our species cannot afford to get these things wrong and not learn from the mistake. Imprisonment is the absolute bare minimum, there should be executions. We should be absolutely, totally certain of whether masks work on an airborne disease that's THREE YEARS OLD! Top officials should be happily staking their lives on this, since they know they've taken every possible step to be totally certain that their advice is correct.

Fauci delenda est.

I'd say one problem is: even if masks are mildly effective as such, are they as effective as people think they are? If masks are mildly effective but people think they are super effective, they're going to engage more in behavior that will enable them to get or spread the disease (ie. moving out and about while mildly sick), which then might compensate or overcompensate for the mitigatory effect, particularly if the masks are worn incorrectly but the user thinks it's on correctly.

It isn’t logical that masks work. It is akin to believing that a chain link fence will keep out mosquitoes.

If covid was spread via droplets, then yeah masks “make sense.” But aerosols transmissions makes masks act like a chain link fence v mosquitoes

This is nonsense resulting from trying to apply macroscopic intuitions at a microscopic scale. Completely unintuitively, N95 masks filter particles smaller than 0.3 microns better, even though the macroscopic intuition is that smaller particles would more easily fit through the holes. Here's a pop-science explanation from Wired.

Thanks for that second link with the interview.

[interjects]… please do not call me an expert. I'm a guy who has worked in the field for some time. That has to be the message. I don't work with models, I don’t make predictions. I don't hassle people or chase them on social media. I don’t call them names… I'm a scientist. I work with data.

I'm quite surprised because it seemed logical that masks would work. Why do doctors wear them if they don't work?

The history of medicine is littered with harmful non-evidence based practices. And it's not just pre-modern medicine either. For example, in the 1930s, among 1000 schoolchildren in New York, 61% had had their tonsils removed. When the remaining children were presented to doctors, all but 65 of them were told they needed tonsillectomies. Even in the 1970s, tonsillectomies were the 3rd most common surgical procedure in U.S. hospitals.

The idea that the medical consensus is 100% correct in 2023 requires us to adopt the magical belief that previous errors have all been corrected, despite the fact that new errors are constantly being discovered.

How many unnecessary colon and breast cancer screenings are being performed even today? What is the cost, both in money and human suffering that these screenings impose?

Doctors wear masks for the same reason regular people wear masks: social conformity and medical theater.

I actually think there is a good reason for doctors to wear masks: spit. Quite often, saliva just gets ejected from the mouth, whether it's from coughing or merely speaking. It doesn't really matter if masks prevents spread of disease via spit, it's just gross to get spat on, and this is a situation where I'm comfortable saying that it "just makes sense" that masks will block ejecta from the mouth. It goes both directions, people don't want to be spat on by doctors, and doctors don't want to get their patients' spit in their mouths.

Anecdote: my mother noticed a cashier at her local grocery store had briefly stopped masking when the mandates lifted, but went back to wearing one. When asked, the cashier said she wasn't worried about COVID, but she had realized that the mask prevented her from getting customers' spit in her mouth. And cashiers don't have to get right up in their customers' faces.

In medicines all such good reasons should be verified, with RCTs if possible. So many things that “just makes sense” were proven wrong.

As for spitting, it is how people have interacted with each other for thousands of years and it never bothered anyone except in some gross cases. To become concerned about it now would indicate that the person has too much anxiety.

Just for a note, I never masked as a pharmacist, except when administering vaccines. For vaccines it is a protocol that we have to strictly observe but for other interactions it is optional. I also noticed that in other countries covid vaccines are administered differently. For example, we do not clean the skin with alcohol wipe (unless visibly dirty) because the studies showed that it makes no difference.

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