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It Doesn’t Matter if Masks Work
I’ve been trying to stay out of this. I really have. But just can’t help myself. I’ve read every possible opinion about preventing the spread of COVID using masks. Some people say they don’t work at all. Others say that they work extremely well. Others say they work, but they don’t work because you morons can’t use them correctly. And there are many other variations out there. I haven’t posted on this topic, partially because I don’t know what I’m talking about. I don’t really understand what just happened. So much of this makes no sense. But I can no longer restrain myself. Allow me to propose my own theory: Nearly all the theories I’ve read are wrong. All of them. Well, pretty much. In my view, at least.
The use of statistics in medicine is complex. There are lots and lots of variables, most of which are unknowable. Discerning the impact of a treatment from random chance can be tricky. We try to follow a wide range of studies, but they often don’t agree. But let me try to illustrate my point at first by moving away from masks, and talk briefly of heart disease. This will seem off-topic at first, but you’ll see where I’m going soon. And the doctors in the audience may catch me over-simplifying the data a bit. I’m just trying to explain a general concept here, so if you send me a personal message that involves p-values, I promise I won’t read it. And this post is covering some complex topics, so it will be longer than my usual post. If you can’t stand the idea of reading anything else about masks, I won’t blame you if you just keep scrolling.
Ok. Because heart attacks are often fatal, we spend a lot of time and effort trying to prevent them, rather than treating them after the fact. There are two types of prevention, in the cardiovascular world. There is primary prevention, in which we take people who have not had a heart attack, and we give them some form of treatment, in an effort to avoid their first heart attack. Then, there is secondary prevention, in which we take people who have had a heart attack, and we give them some sort of treatment, in an attempt to prevent subsequent heart attacks.
Let’s start with secondary prevention. If you take 1,000 people who have had had a heart attack, and you give them all statin drugs, will you prevent subsequent heart attacks? Yes. The data is simply overwhelming. Statins work extremely well in this environment, all the studies show pretty much the same thing, and there is no longer any debate on their effectiveness in treating heart patients. In fact, it has become unethical to do placebo trials on such patients, because it is so obvious that heart patients live longer when you give them statins, you just can’t deny half the people in the study a treatment that you know will prolong their life. You are not allowed to intentionally kill people while doing research. If you know a drug works you can’t deny it to half the people in the study. So, yes, statins work extremely well when given to people who have already had a heart attack.
Ok. What about primary prevention? Well, in primary prevention studies, the data on statins is much more complex. Some studies show reasonable benefit, others show small benefits, and some show little benefit at all. While secondary prevention studies look very similar to one another, primary prevention studies are all over the map.
This seems odd, doesn’t it? You’re using the same drug (statins) to treat the same disease (heart attacks), but you’re getting different results in primary prevention vs secondary prevention studies. They should show the same thing, right?
Can you figure out why there are such striking differences between the two types of studies? I’ve given hundreds of speeches to various doctors’ groups across the country on this topic, and I would be embarrassed to tell you how many physicians in my audiences can’t figure out the difference. Do you know what it is?
Since the treatment is the same, and the disease is the same, the difference must be the patients, right?
Think of it like this. In a secondary prevention study, all of the patients have heart disease, and you know it. They have had a heart attack. You don’t need a cholesterol panel or a blood pressure check to figure out if they are at risk for heart disease. You know they have heart disease.
Now, suppose that statins reduced risk of heart attack by 50%, just for simple math. If all of the patients in the treatment group have active heart disease, you might hope that your prevention numbers might get as high as 50%, right? It won’t be that high, of course, because not everyone who has a heart attack has a second heart attack. But many do. So your reduction of risk and heart attacks looks pretty good in that population because they all have heart disease.
Ok, so now think of a primary prevention study. You’re going to take 1,000 people who have high cholesterol, and you’re going to treat them all with a statin, and you’re going to see how many heart attacks you can prevent. Suppose you’re using the same statin, with the same 50% reduction in heart attacks. So will you be able to reduce heart attacks in that group by 50%?
No, because not everyone with high cholesterol will have a heart attack. OK, so how many people with high cholesterol will have a heart attack? It’s hard to say because that would depend on many other variables. But it’s probably not half (depending on how high their cholesterol is), and it may not be 25%. Around 75% of heart attacks occur in people with normal cholesterol.
So treating people based on one risk factor (say, high cholesterol), will result in you treating a lot of people who will never have heart disease. Whether you treat them or not.
Suppose you had a crystal ball, and you picked out 1,000 people with high cholesterol that you somehow knew would never have a heart attack. Your crystal ball said they were all going to die of pneumonias or car crashes or something. Ok, so now you give all 1,000 of them a statin. What will your success rate be? Zero percent. Because none of them were going to have a heart attack to begin with.
So let’s suppose, that in your high cholesterol study, 25% of the people in your study group will eventually have a heart attack. And suppose statins reduced the risk of heart attacks by half. In that case, the very best your statin could do would be to reduce the risk of heart attack by 12.5%. So you’re only getting a 12.5% reduction in heart attacks, even though the risk reduction from our hypothetical statin is 50%.
But it will probably be less than 12.5% because not everyone will take the medicine properly, some of them will take up smoking, some of them will get older during the study and develop diabetes, and so on. So in your high cholesterol study, a drug with risk reduction numbers of 50% may work less than 10% of the time.
Why? Because a lot of the people that you’re treating didn’t have heart disease to begin with. Whereas in the secondary prevention study, they all had heart disease.
In my speeches, I tell my doctors that if they’re using statins for primary prevention, they had better know what they’re doing with diagnostics, or else whatever treatment they use won’t work. No matter how effective it is. And if all they’re doing is giving statins to people with high cholesterol, well, good luck.
Ok. So after all that, let’s talk about masks.
Do masks prevent the spread of COVID-19? Maybe. Some studies have shown no benefit at all, but some have shown small risk reductions. Not 50%. Maybe 10%? If you choose your data carefully and squint a bit when you read the stats section, maybe 20%? Maybe. But probably less than that. And again, according to several studies, it’s close to zero percent. So the real benefit of masks, under ideal circumstances, is difficult to say for sure.
My point, though, is that it really doesn’t matter how effective masks actually are.
Let’s say for example that you went to a grocery store last year, at the height of the pandemic. Suppose there were 100 people in that grocery store. And suppose all 100 people, including you, are wearing masks. Ok.
How many of those people have active COVID-19 infections at that moment? Half? Of course not. All of these people are healthy enough to go shopping. 25%? Heavens no. Let’s just say for the sake of argument that there are five of those 100 people who have active COVID-19 and don’t know it. If they’re feverish and coughing their heads off, you’ll probably give them some space anyway. So I’m talking about asymptomatic, or nearly asymptomatic, but active, COVID-19 infection. Again, let’s say there are five of those walking around your grocery store.
So your risk of becoming infected with COVID-19 is 5%, then, right? Well, no. How many of those 100 people are you likely to have extended close contact with?
Remember that the vast majority of the infections we tracked occurred at home, or other places where people are in very close contact, in very small spaces, with so-so air circulation, for extended periods of time. Transmission of COVID-19 in public places is rare, whether you wear a mask or not.
So you could argue that we should be wearing masks at home, but not once you leave your house. I don’t think that would help much, either, but I suspect it would work better than wearing masks in public. That would be an interesting study. And good luck enforcing compliance in that study. Talk about hypothetical benefits…
Anyway. So those five people wandering around the grocery store do not give you a 5% risk of catching COVID. Let’s just guess your risk of catching COVID-19 in that store is 1%, just for the sake of argument. I think that’s really high. Some of you may think it’s a bit low. But whatever.
Remember that on that floating petri dish – The Diamond Princess – over 80% of the elderly passengers did not get COVID-19. And they were up to their necks in it for weeks. And they were all old. They weren’t middle-aged healthy people just wandering around a grocery store for 20 minutes.
But again, the exact number doesn’t matter much. Pick a number that makes you happy. But regardless, it’s low.
Now, let’s suppose that masks can reduce the risk of COVID-19 transmission by 20% when used properly. Firstly, I think that’s extremely optimistic, based on the studies we have. And secondly, I would guess that the number of masks in that grocery store being used properly is vanishingly small. But let’s suppose that the studies are wrong, and the grocery shoppers are unusually vigilant with sterile techniques, and the masks in this grocery store actually do reduce the risk of COVID-19 transmission by 20%. Right.
So if your risk of getting COVID-19 in that store was 1%, and you reduce that by 20%, now your risk of getting COVID-19 is 0.8%.
So you reduced your risk of COVID-19 by 2 people out of 1,000. That’s not nothing. But it’s close. And again, I think that’s extremely optimistic.
Why are masks so ineffective, even if we presume that they are effective? Because almost everybody that is wearing them does not have COVID-19. So in those people, there is no chance that they could provide any benefit, regardless of how effective they are.
It’s like giving statins to people who have high cholesterol but don’t have heart disease.
Ok, look. The stats geeks out there are going to notice some shortcuts I took with my math. I used simple numbers simply to make a point. This isn’t meant to be a precise statistical analysis. And others may argue that it’s no big deal to wear a mask. With no real downside, why not, right? And the fans of masks may be plugging more optimistic numbers into my ham-fisted formulas above. But it won’t matter much. Maybe a little. Not much.
Also, just suppose that a new study came out tomorrow that showed that masks reduced the risk of COVID-19 by 50% or something, in that particular study, when you use a certain mask, with a certain sealant, for a certain period of time, or whatever.
Ok, that’s swell. But I don’t care.
Not until somebody can show me some very real benefit in an actual population of actual people leading their actual lives. If masks work only when used properly, but no one uses them properly, then that doesn’t help.
The research on statins was very exciting early on, but their use didn’t really take off until doctors started to see heart attack rates drop significantly in the population at large. That meant that they didn’t just work under the ideal circumstances of a controlled study – they worked in the real world, too. That’s when we really started using a lot of statins.
Also, you can reasonably argue that masks were a good idea, because they got people to leave their houses, and they got the economy going again. That may be true, but that’s not my point.
And I emphasize that I’m speaking of normal people wearing masks in public. I’m not discussing the use of masks or other protective equipment in medical settings. That’s not my point, either.
So what is my point?
If you feel safer wearing a mask, by all means, be my guest. I don’t think they’re entirely benign, but I agree that the risk from wearing masks appears to be small. So whatever.
But if you’re curious as to how much protection that mask is actually providing you, color me skeptical. I obviously don’t know the real benefit of wearing masks, but I strongly suspect that it is extremely, extremely small. A suspicion that has been borne out by population studies around the world.
I openly acknowledge that I don’t know the precise risk reduction provided by masks used in public settings. But I don’t think anyone else does, either. I’m just saying that whatever that number is, I suspect it’s really low.
And I think it’s important that we think this through because this is going to come up again. Probably soon. And next time, we should have a plan.
A plan with some real-world data behind it.
Our response to this virus has been a fiasco. I hope we learn from it.
I suspect we won’t.Published in General
The virus blew through every single mask mandate, I think without exception. Now they want to force everyone, including the vaccinated, into a mask without any explanation. I am so sick of this.
The scenarios where they do any good are very narrow and very obvious.
It might change the next election, but it really bugs me that there will never be decent hearings about this. I don’t think they work that way. It’s not like a civil trial or something.
I am really tired of not being able to understand people because they mumble in their masks. It’s like my first few months in China. I buy something, the person says something and I nod not really sure of anything.
I just got done playing the Fox news house doctor over and over. The Delta variant breaks through on some vaccinated people and they have one hell of a lot of virus in them. There was no numerical indication of how big the problem is. So masks are going to mitigate this. Even though they never did a damn thing on that level so far.
So obviously, in the next few weeks they are going to tell us all about the known dynamics vaccine failing in “X” amount of people.
This is never going to happen of course.
Dr. Bastiat, as a person who has studied and applied statistics for many years, I have to say you rank very high among medical doctors in terms of your understanding of probability and statistics. This was a very good article.
And I’m still trying to figure out if I want to keep taking my statin prescription, in the absence of any actual negative health outcomes.
Thanks – very kind of you to say!
And as I mentioned, despite their effectiveness & safety, the use of statins is a complex decision…
I just heard another report. Some people get really sick and some people don’t have any symptoms.
I guess you could infer this doesn’t happen to every protected person that gets the virus. I’d like to know the percentage.
Can you imagine if they have to invent new vaccines because they can’t control the mutations because of this? God what a waste of capital.
I was listening to some analysis on red eye radio right now. PBS NewsHour confronted Fauci with Ron DeSantis’ assertion that masks are ineffective at the aggregate level. I looked up the articles with the quotes. Fauci didn’t deny it.
They have this breakthrough issue with the Delta variant and they are throwing the kitchen sink at it for political reasons. That’s what I think. Everybody over a certain age or with comorbidities has deliberately chosen to screw themselves statistically. They aren’t going to run out of medical resources. They also aren’t going to kill it off to prevent more problematic variants. The masks don’t do jack except make the central planners feel better.
Here’s another one. I’ve heard two different guys on TV saying they have plenty of data to make the vaccines fully FDA approved. What are they waiting for? There has to be a political reason.
I don’t believe that one second.
One of the Fox News doctors just said it’s 1%.
Fox is reporting that it’s going to be FDA approved in August.
One of the guys I was referencing was Dr. Marty Markay who is preettyhostile to the CDC and the administration.
In TN, according their numbers up to 7/22, 305 new hospitalizations for COVID and 200 of them were reported as breakthrough cases.
They are simply numbers available to the public. I maintain we are being lied to by the media.
This vaccine has a history of poor outcomes on reinfection. So FDA approval better not be chased with forced vaccination.
Breitbart has the video cued up.
They didn’t do anything at the aggregate level and we are talking about a very small aggregate problem right now. People have made their choices about the vaccine and we aren’t going to run out of medical resources.
Here is just one more reason to not believe what the CDC tells us about masking or any other Covid-related issues. The CDC is absolutely silent on the issue of millions of illegal aliens infected with Covid that are entering the country, and instead of being quarantined, are shipped out to all parts of the country at government expensive to infect others.
This shows that either the CDC doesn’t think that Covid is really as dangerous as they are making it out to be, or that they are willing to compromise their scientific beliefs for the benefit of a political narrative. And Democrats have the gall to call themselves the “Party of Science.”