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nopie  1yr ago (vinayprasadmdmph.substack.com)   Edited 1yr ago   2933 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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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"?

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.

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