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The Illusion of Knowledge

July 19, 2020

“The greatest obstacle to discovering the shape of the earth, the continents, and the oceans was not ignorance, but the illusion of knowledge.” – Daniel Boorstin

Last month, I published a newsletter on the Illusion of Safety and how businesses and schools would be scrambling to prove that they had found a way to keep us safe, just please send that money.  I’ve been wondering if masks provide the illusion of safety, but then I read that quote and realized mask usage is really rooted in the illusion of knowledge.

This is not an anti-mask newsletter.  If you are coming here for support of your God-given right to go mask-less in public, you will be disappointed.  How could I possibly look a black American in the eye right now and claim mask mandates are infringing on my civil liberties?

If you came here thinking I will definitively conclude masks are foolproof…well, let’s be honest, you know better.  Some may even stop reading now because their mind is made up and I’m obviously ignorant/callous.

Masks are a tricky topic.  Somehow they have become politicized.  There’s a signal effect to masks.  A badge of honor.

A few weeks ago, I got into a…discussion…with my mom on the topic of masks.  The evidence was piling up on the efficacy of masks and I was on the wrong side of history.  I reminded her that I wasn’t opposed to masks, I simply thought their benefit was overstated.

Wearing masks is the new “flatten the curve.”  Intuitively simple to digest.  But have we stopped and asked ourselves where the data is really coming from?  Before you get defensive, can you tell me where six feet of social distancing is coming from?  Or have we just said it so much that we assume it to be true?  Would you be surprised to learn that WHO suggests 3 feet, not 6 feet, of social distancing?

The messaging around masks has been atrocious and has contributed to the confusion.  In January, the NYT’s published an article entitled, “Many in China Wear Them, but Do Masks Block Coronavirus?”  The subtitle was, “They may help, but experts say it’s more important to wash your hands.”  When was the last time someone in Walmart pulled a gun on someone for not washing their hands properly?

That same article quoted Dr. Julie Vaishampayan, chairwoman of the public health committee for the Infectious Diseases Society of America, “We worry about people feeling they’re getting more protection from the mask than they really are,” she said. “Washing your hands and avoiding people who are ill is way more important than wearing a mask.”1

Momentum for masks really began picking up in April.  A paper posted (not published or peer reviewed) by a UC Berkley PhD candidate in computer science concluded that if 80% of the population used cloth masks, the transmission of covid would be reduced by 92%.  He included lots of official looking graphs.  “Ninety-nine percent of people are walking around wearing masks in Hong Kong,” said the researcher, De Kai. “In Hong Kong, we’ve actually never had to have shelter in place because we’ve done the other things right.”  Intuitively easy to grasp.  Mask = defeat covid.2

A study led by a team of researchers at Texas A&M was certain that facemasks alone were the key to defeating covid, estimating “that rules requiring the wearing of masks prevented at least 66,000 coronavirus infections in New York City between April 17 and May 9, and 78,000 infections in Italy between April 6 and May 9.”  It was heavily covered in the news.3


WaPo Editorial Board (not just an article):

Psychology Today:

At the same time, a study led by scientists at the Britain’s Cambridge and Greenwich Universities concluded that facemasks could completely stop the spread of covid, “These analyses may explain why some countries, where adoption of facemask use by the public is around 100%, have experienced significantly lower rates of COVID-19 spread and associated deaths.”4

This, too, was covered by the media.



Newspaper Formerly Known as Tom Brady Fanboys:

In May, the NYT’s Editorial Board published an article entitled, “The Most Patriotic Thing You Can Do Right Now.”   This was Memorial Day weekend, so the NYT’s was paying homage to those that made the ultimate sacrifice.  On masks, “The science, while still evolving, backs that up.”5

More recently, a pair of researches at UC-Davis concluded that wearing masks could reduce transmission rates by 65%.6

“On the issue of masks, I’d like to restart — because we’ve learned a lot,” Blumberg said. “We’ve learned more due to research and additional scientific evidence. What we know now is that masks work and are very important.” 

“Everyone should wear a mask,” Blumberg said. “People who say, ‘I don’t believe masks work,’ are ignoring scientific evidence. It’s not a belief system. It’s like saying, ‘I don’t believe in gravity.’ 

“People who don’t wear a mask increase the risk of transmission to everyone, not just the people they come into contact with. It’s all the people those people will have contact with. You’re being an irresponsible member of the community if you’re not wearing a mask. It’s like double-dipping in the guacamole. You’re not being nice to others.”

“If you care about your family or friends, or if you care about your community, wear a mask.”

OK, setting aside the fact that Dr. Blumberg missed his calling as a guest speaker for “How To Win Friends and Influence People,” are we really that sure?

According the National Institute for Occupational Safety and Health (a division of the CDC), has a very helpful graphic on masks.  Pay particular attention to the highlighted red box on transmission.7

Wearing a mask has gained a lot of traction in the last few months.   What I find interesting is that Dr. Blumberg said, “We’ve learned more due to research and additional scientific evidence.”  But have we?

Fivethirtyeight ran an article at the beginning of July actually entitled, “The Science of Mask Wearing Hasn’t Changed, So Why Have Our Expectations?” and interviews some experts in this field, including Dr. Michael Osterholm. Unlike me, Dr. Osterholm is eminently qualified.  He’s is an American infectious disease epidemiologist, regents professor, and director of the Center for Infectious Disease Research and Policy at the University of Minnesota.  He also provided the quote that started this newsletter.8,9

“Another challenge we face with understanding masks and respiratory protection is the increasing number of poorly conducted and inadequately reviewed studies getting published in rapid succession. Some are even being widely distributed before they are reviewed and published. The media tends to jump all over them assuming they provide newly found and definitive answers about mask protection.” (emphasis mine).

Just because masks have become more socially acceptable, does that mean the evidence actually piled up?  Or did we simply change our perception of masks?

Do we now so fundamentally believe in masks so much that anyone that has a question about them must not believe in gravity, either?

If we have so much new research on masks, why does the CDC still use the graphic above?

Why does the WHO say on its website:

“There is limited evidence that wearing a medical mask by healthy individuals in the households or among contacts of a sick patient, or among attendees of mass gatherings may be beneficial as a preventive measure.  However, there is currently no evidence that wearing a mask (whether medical or other types) by healthy persons in the wider community setting, including universal community masking, can prevent them from infection with respiratory viruses, including COVID-19.”  (emphasis mine).10

In April, a team of experts was asked to provide a rapid consultation to the Office of Science and Technology on masks worn by the public.

The evidence from these laboratory filtration studies suggests that such fabric masks may reduce the transmission of larger respiratory droplets. There is little evidence regarding the transmission of small aerosolized particulates of the size potentially exhaled by asymptomatic or presymptomatic individuals with COVID-19. The extent of any protection will depend on how the masks are made and used. It will also depend on how mask use affects users’ other precautionary behaviors, including their use of better masks, when those become widely available. Those behavioral effects may undermine or enhance homemade fabric masks’ overall effect on public health. The current level of benefit, if any, is not possible to assess. (emphasis mine)11

And the type of mask we wear has a dramatic effect.  That same paper cited a study that found, “Among adults, N95 masks provided 25 times the protection of surgical masks and 50 times the protection of cloth masks.”  Maybe that surgical mask I keep in my car isn’t quite as safe as I think it is (or the store that requires I wear it thinks it is).   Maybe the cool cloth one with a Philadelphia Eagles logo is even worse?12

Just because we keep saying the evidence is mounting doesn’t necessarily make it so.

One of the arguments for masks is that intuitively it just makes sense.  And I agree, it just feels like they should help.   Otherwise, why would surgeons wear masks?

On surgical masks, Dr. Olsterholm said, “I think most people would be surprised to learn that even though their purpose was to prevent surgeons from dripping their secretions into the incision on someone in a surgery, there have been three clinical trials of surgical masks and how well they do that and none of them have shown any difference in wound infection rates whether the staff were wearing masks or not. So, they’re not even that effective for what they were intended.”  A powerful surgical mask lobbyist in a K-street breakfast booth facepalms.

But while we’re discussing arguments rooted in intuition, let me ask a question.  Why is California one of the states experiencing a surge in cases?  If masks are as foolproof as people believe, shouldn’t CA be among the most successful states right now?

“Science shows that face coverings and masks work,” Newsom said when on June 19th he ordered Californians to wear a mask outside their home. “They are critical to keeping those who are around you safe, keeping businesses open and restarting our economy.”13

According to the NYT’s heat map on mask usage, California pretty much leads the way on masks.

Below are three states from NYT’s homepage.  California is the only one to mandate mask usage in June.  Can you pick out California?

California is the first one.  The second and third graphs are Texas and Florida, respectively.  To be fair, California is larger than either Texas or Florida (40mm vs 29mm vs 22mm) so it is doing better on a per capita basis.  But considering that CA was perhaps the most aggressive state in shutting down and masks are so widely used there, I’m surprised the difference isn’t more stark.

Georgia was the first state to re-open. The governor is suing the mayor of Atlanta over face masks. Why doesn’t their curve look far worse than everyone else’s curve?

Are we sure masks are as effective as they are being made out to be?  Could masks just be one of the many contributing factors to slowing the transmission?

Most importantly, if we are overstating the effectiveness of masks, aren’t we potentially exposing ourselves to more risk?

If I believe masks will keep me safe, might I engage in behavior I would otherwise avoid?

One of his chief complaints is about the CDC’s sudden reversal on mask wearing on April 3rd without corresponding change in the science.  The revised guidelines, “CDC recommends wearing cloth face coverings in public settings where other social distancing measures are difficult to maintain (e.g., grocery stores and pharmacies) especially in areas of significant community-based transmission.”

Remember, the CDC initially said don’t wear a mask.  This change came without a single scientific explanation for the change.  The CDC didn’t cite emerging evidence or a recent study, they simply changed their view without an explanation.

“Never before in my 45 year career have I seen such a far-reaching public recommendation issued by any governmental agency without a single source of data or information to support it.” Dr. Osterholm said.  “How many cases of COVID-19 will occur when people using cloth masks and not understanding the limitations of their effectiveness participate in activities with others where virus transmission does occur?”

The bottom line is that we simply don’t have enough information to conclude how effective masks are in preventing the spread of covid-19, but the media is presenting it as if we do.  And we are buying into it.  And we are criticizing those that don’t instead of admitting that maybe the evidence isn’t overwhelming but some exists nonetheless.

Before the “masks don’t work” crowd gets too excited, please note that “lack of data” isn’t the same as “masks don’t work.”

The WHO funded a meta-study last month on transmission of covid/SARS/MERS based on the analysis of 172 observational studies and 44 comparative studies.  Those underlying studies each have flaws, which flow up into this analysis (one of the big ones is that most studies have been done in hospitals, not community settings).  But by presenting an aggregation of data, the authors hope to mitigate the individual flaws and make some interesting findings.14

On facemasks: “Medical or surgical face masks might result in a large reduction in virus infection; N95 respirators might be associated with a larger reduction in risk compared with surgical or similar masks.”

Their confidence in that analysis?  Low.

  • Assuming no physical distancing and no mask, the transmission rate was 17.4%.
  • Assuming no physical distancing with a mask, the transmission rate dropped to 3.1%.

So wearing a mask could reduce the transmission rate by 82%.  (17.4%-3.1%)/17.4%

That’s a huge reduction.  That’s also a great reason for wearing masks.  For those that say masks don’t work, here would be some concrete evidence that says they do.

But was anyone else surprised that the transmission rate was just 17.4% to begin with?  When we read statistics that extrapolate mortality rates across the entire population, let’s try to remember that’s not how a virus works.

If I come into contact with someone with covid, we are less than 1m apart, and neither of us have a mask on, the transmission rate is 17.4%, not 100%.

That also means we should be wary of any statistics touting the improvement masks make along the lines of “masks are 97% effective!”  Well, the first 83.6% of that was virology/genetics/other factors.  Let’s not overstate the benefit the masks are providing.

Using the CDC’s best estimate of mortality rates for my age bracket, the likelihood of me dying from covid if I come into close contact with someone that has it:

Without a mask                  0.069%

With a mask                      0.012%

That’s a compelling drop.   Is that enough for me to say, “I should wear a mask when I am in crowded places or talking to an immunocompromised person?”  Yes.

But across 1,000,000 people, that’s just 572 lives saved.  I’m not sure that ties out with the story we are being presented about masks.

And that’s the crux of my issue with how masks are being portrayed right now.

  • If I don’t wear a mask, I hate my neighbors, I’m ignorant, and I must believe the earth is flat.
  • If I do wear a mask, I am compassionate, enlightened, and a patriot and I could never possibly spread the virus.

Neither of those are true.  Masks seem to help, but they aren’t 100% effective.

Do they help slow the transmission of covid?  Yes.

Are the next best thing to a vaccine?  No.

Just as interesting, protective eye wear has a significant effect on transmission rates.  Raise your hand if you were aware of that before now.  I certainly wasn’t.  Eye protection decreased transmission by 66%.  Not quite 82% like the masks, but not immaterial, either.

  • Assuming no physical distancing and no eye protection, the transmission rate was 16.0%.
  • Assuming no physical distancing with eye protection, the transmission rate dropped to 5.5%.

That’s also very compelling.  But why isn’t eye wear getting attention like face masks?  If you’re a rabid mask wearer, shouldn’t you also be a rabid wearer of eye protection?  “What’s wrong with you, don’t you care about your neighbor?” – concerned citizen with swim goggles on.  Maybe we are latching onto masks because they are so intuitively easy to understand, they are cheap and easy to use, and it sends a signal to those around us, not because the data supports it?

The study’s conclusions:

  1. The findings of this systematic review of 172 studies on COVID-19, SARS, and MERS provide the best available evidence that current policies of at least 1 m physical distancing are associated with a large reduction in infection, and distances of 2 m might be more effective.
    1. Last week I joked about college administrators running around to classrooms to measure six feet of space and how changing that to five feet could dramatically increase in-room usage. Here’s some evidence that suggests 3 feet might be nearly as effective as 6 feet.
  2. These data also suggest that wearing face masks protects people (both health-care workers and the general public) against infection by these coronaviruses, and that eye protection could confer additional benefit.
  3. None of these interventions afforded complete protection from infection, and their optimum role might need risk assessment and several contextual considerations.

Distance, not masks, is the #1 precaution we can take.

If distance can not be maintained, masks are better than nothing if you don’t increase your risky behavior.

If I’m out and about and keeping 6 feet of distance from everyone, please don’t run up to me and start screaming at me to put a mask on.  And I promise not to scream that the CDC says that a surgical mask “does NOT provide the wearer with a reliable level of protection from inhaling smaller airborne particles and is not considered respiratory protection.”

Recall those stories about why masks are so effective?

  • The De Kai study – once experts dug in, they determined it did not account for dose or length of exposure, two critical components to transmission. This highlighted the risk of experts outside this field providing opinions as facts.
  • That study by the Texas A&M team that kicked off the mask feeding frenzy – it has been so discredited by the scientific community that researcher have signed petitions to take it down and Johns Hopkins published a paper demanding a retraction.15
  • The study out of England? Some initial peer responses highlight caveats:
    • In this paper, the authors optimistically assume that 100% of transmission events could be prevented with face masks. In reality, 15% of contacts and a third of all contact hours occur in the home, and therefore these transmission events would not be prevented with face mask use. Therefore, the likely impact of face masks is much smaller than is predicted in this modelling study.16
  • The New York Time’s Editorial suggesting that wearing a mask is the most patriotic thing we could do? You didn’t click on the link imbedded in the “the science backs this up”, but if you had you would know that it does not take you to a peer reviewed study, but instead takes you to a Vanity Fair article.  In turn, that Vanity Fair article was about the De Kai study that has been discredited.

Is it possible that these studies, even if later discredited, are contributing to our increasingly rabid beliefs on masks?  Couldn’t that result in the wrong decision?

As usual, many will counter with, “better to be safe than sorry.”  One final thought from Dr. Osterholm.

“I understand why many would argue that some benefit is better than none, but I believe that we must approach this assumption with caution. The messaging that dominates our COVID-19 discussions right now makes it seem that if we are wearing cloth masks you’re not going to infect me and I’m not going to infect you. I worry that many people highly vulnerable to life-threatening COVID-19 will hear this message and make decisions that they otherwise wouldn’t have made about distancing because of an unproven sense of cloth mask security.”

If we re-open based on the false premise that masks provide near 100% protection, cases may continue to surge.  Deaths could rise.

Let’s give masks the appropriate level of consideration and let that be rooted in data, not an emotional affiliation with a political party.

At some point, someone might suggest that six feet of physical space can be replaced with 3 feet + a mask, and I want us to make a reasonable decision about the true safety of that proposal.

The illusion of knowledge can lead to the illusion of safety.




Click to Open: The Pensford Letter PDF