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The Danish Mask Study

By November 18, 2020Commentary

This is the fuller post.   The headline result–wearing a mask makes no difference in cases or in level of transmission in the community.   It is obvious to all of us now, that this is true, as we can see the case growth in areas of the country with extremely high mask-wearing rates.  Here is the cite.  (Danish Mask Study)  Coupled with the withdrawal of the county study which purported to show a benefit based on limited time period study, this should put an end to any Governor claiming that mask mandates are backed by science and data, but it won’t.  As I noted in my flash report, people are already coming out with all kinds of BS criticisms of the trial. It is amusing in a sense, that people who just accepted all the mask modeling “research” without any quibbles or skepticism are finding all kinds of criticism directed at an actual randomized trial attempting to answer a real-life question–what is the effect of wearing a mask in the community.

Before describing the study and its findings, let me make a couple of preliminary observations.  I have been reading medical research for 40 years and science papers for even longer.  When you read this study and you know the history of the attempt to get it published, you are immediately struck by what the authors must have been forced to do to get any reputable journal to publish it.  They were clearly forced to constantly refer to limitations and caveats about the study and there is a discussion about the confidence intervals around the results that you absolutely never see in the published reports of research.  What kind of science is it that decides in advance what the results have to be and tries to suppress any research that challenges those pre-ordained results?  When I complain that science has become completely politicized, what happened to this study is Exhibit A.

Unlike all the garbage modeling studies about mask mandates and mask wearing reducing cases, this was an actual randomized trial on the critical question–does wearing a mask in the community affect the level of transmission, the number of cases, in that community.  It is real-life, we aren’t wearing masks in a model simulation or in some experimental room.  We wear them in the community, in real life, properly, improperly, touching them, not touching them, with gaps, without gaps, changing them frequently or not, washing them or not.  That is the reality of mask-wearing.  That is what this study replicated.

6000 people participated in the study.  3030 were randomly assigned to the mask group and 2994 to the control arm.  Out of the entire group 4862 completed the study period.  These were adults who spent more than 3 hours a day outside their homes and didn’t wear masks at an occupation.  Both the mask wearing arm and the non-mask wearing arm were told to follow social distancing measures.  The mask-wearing group was encouraged to wear a mask outside their home and were given 50 surgical masks for this purpose.  So better masks than cloth ones.  The primary outcome was number of infections after one-month.    42 people got infected in the mask wearing group and 53 in the control group.  Because more dropouts occurred in the mask group, there was no statistical difference in infection rate.  One interesting little nugget in the characteristics of the groups is that more people in the control arm had what might be considered higher-risk occupations than in the mask wearing arm.  Yet still no difference in infection rate.

Some of the criticisms are that the data on mask usage were self-reported, this only tested the effect on the mask wearer, not whether they might be less likely to infect others, and other niggling concerns.  The real criticism is that it doesn’t fall in line with the orthodoxy on all of us needing a mask glued to our face 24 by 7.  Self-reported adherence was good, with over 90% of the mask-wearers saying they largely complied with the recommendation and almost half saying they always did.  Taking out the 7% who reported poor adherence did not change the primary finding.  And very importantly, looking only at those persons who reported always complying with the mask recommendation also did not change the outcome.  It appeared there was very low in-home transmission that caused the infection in either arm of the study, so most transmission was occurring in the community.  Another interesting finding was no difference in infection with other respiratory viruses.

This was a well-designed study. If masks made a difference in the community, it would have been seen in this large a group. And that distinction between protecting the wearer versus others makes no logical sense. Think about it. If wearing a mask doesn’t do a better job of keeping you from getting infected, i.e. keeping the virus from coming in, why would it do a better job of keeping it from going out? In fact, you might expect the opposite, there is less pressure in the inhale than the exhale.

And if the problem is that people who are infected aren’t wearing a mask then wouldn’t we expect to see even higher levels of community spread among the non-mask wearing population–if masks worked, at least on a relative basis the masked people would be better protected from infection than the unmasked ones.  Think about it logically for a minute, if lots of people aren’t wearing masks, and they weren’t at this time in Denmark, according to mask theory there is a tremendous risk of exposure in public.  So there should be an even greater protective effect of a mask protecting the wearer from getting infected, because there is more opportunity for exposure to the virus.  But according to this study, a mask did no better job of protecting the wearer in this hazardous environment than did not wearing a mask.  If anything, this aspect of the trial strengthens the finding.

So wear them if you want to or have to, but don’t for one second think they are offering you or others any significant degree of protection.  And that is my concern about the mask mandate fetish, not only are people being lied to about the science, but they are being misled into thinking they will have a level of protection they won’t.

Join the discussion 83 Comments

  • arch1 says:

    Kevin, believe it or not my mind isn’t made up. At any point I obviously have some notion as to the likelihood of various claims based on what I’ve learned to date, but I do try to revise these as new info rolls in. So if you or others have on-point responses to my points/questions above, I’d very much like to hear them, as I’m not an expert in this field.

    That said I do like to subject incoming info and claims to scrutiny where appropriate and where I can meaningfully do so. In other words (and I suspect you might agree here:-)), I think there is value in a healthy skepticism.

  • Arch1 says:

    Kevin, in my point 1 I am simply explaining why I believe that a key claim of yours is incorrect, and inviting you to set me straight by providing specifics that you *should* be able to provide if it *is* correct. I plan to adjust my current likelihood of your being right up or down based on your response. This is not closed-mindedness, but instead the very essence of rational argumentation.
    I truly want to learn and move my understanding towards an ever better graso of what’s really going on here, whether that ends up being your current view, mine, something between, or something else entirely.
    if this is your desire as well, I encourage you to engage with the substantive points i have raised rather than making unfounded assertions about my willingness to update my beliefs. Thanks.

  • Kevin Roche says:

    okay, I appreciate the comments, I think I made myself pretty clear and summarized the study accurately. You have a different perspective, which is fine.

  • arch1 says:

    Kevin, you appear to have shunted me off to a side room where, as a consequence of my raising legitimate issues with which you don’t wish to engage, I cannot participate further in the discussion.

    I suspect this is your standard operating procedure for inconvenient challenges to your claims. In this case, it has the nice side benefit (from your perspective) that I can’t even link to today’s referenced web chat to directly engage with one of the actual study authors.

    Congrats. Your ideas have once again evaded the need to confront and potential evolve in the face of skeptical scrutiny. Perhaps it only shows my naivete, but this is the clearest example of siloed thinking and enforcement of an ideological monoculture I’ve personally encountered on the part of a blog author.

    Without much hope that you’ll follow up on this, I encourage you to take some time during the coming holiday season to reflect on your current approach to arriving at and updating your conclusions and the extent to which it supports real truth-seeking; and the extent to which you are actually interested in seeking the truth, as opposed to seeking that which validates your current beliefs. But for myself I am out of here and won’t trouble you further.

    Take care.

  • Kevin Roche says:

    seriously? seriously?

  • CJ says:

    The study itself says several times that it was not a study on source control which is what the CDC was advocating for with mask wearing. You seem to be taking a study that does not do anything with source control and apply it to your opinion that they don’t do anything with protecting yourself from others.

    This study would have had to been done by testing if Covid positive participants who wore masks vs a control group without it decreases/increased/did nothing with spreading Covid to prove the point you are trying to make here. Though you did say masks should protect viruses coming in if they are protecting them from going out. I thought the CDC said masks were only for reducing the chance of droplets carrying the virus going out but not the virus by itself?

    So I guess we would need a study on Covid carrying people wearing masks vs Covid carrying people not wearing masks and have them go around two different non infected control groups? Then a third split group where everyone wore masks vs those with some infected mingling with non mask wearing non infected?

    “ The findings, however, should not be used to conclude that a recommendation for everyone to wear masks in the community would not be effective in reducing SARS-CoV-2 infections, because the trial did not test the role of masks in source control of SARS-CoV-2 infection. ”

  • arch1 says:

    Since you asked, no – not totally. In frustration I got petulantly sarcastic in the 2nd paragraph (my “Congrats” wasn’t sincere; and on reflection, I doubt that you even noticed the side effect that my removal from the main comment thread meant that I’d lost access to the Danish paper author’s podcast link, so that I couldn’t participate live). I’m sorry about that.

    That said, unless my being “shunted off to a side room” is somehow a figment of my imagination, or just some system issue at my end, I sincerely meant every word of the rest. And I meant it in a constructive vein.

    On the (math, physics, economics, psychology, computer science, and legal) blogs I frequent, ideas are often subject to withering critiques. Bloggers have finite bandwidth and so can’t respond to every comment, and egregiously uncivil, wacko or endlessly repetitive single-issue commenters are sometimes banned for a period or even permanently. But I honestly can’t recall a single instance where a commenter was locked out, or characterized as closed-minded, for politely following up on a civil, relevant, non-wacko objection which the blogger’s initial response had not addressed. And though it’s not as common as it should be, I do see commenters (including myself), and even the bloggers, updating their opinions in light of new information or understandings enabled by discourse on the blog. This is progress.

    So not to put too fine a point on it, but your willingness to so quickly (and on so little evidence) characterize me as unwilling to change my views, combined with your *un*willingness to respond to the substance of my query, left me wondering whether this might be an instance of the pot calling the kettle black.

    I know you’re a busy guy, Kevin, and I know there are obnoxious folks out there that bloggers must somehow deal with. I also appreciate the energy and intellectual courage it takes to coherently formulate one’s ideas on a regular basis, and expose those ideas to public scrutiny. But I also see blogs such as yours as a wonderful opportunity for not just readers, but bloggers, to benefit by encountering new information which can supplement, inform, refine, and sometimes even significantly revise or reverse their views on a given topic.

    In any case, for my part I feel that if someone can open my eyes to something I’ve been blind to, that is a true gift, because they’ve made me a little less wrong. It’s a great feeling.

  • Sam - Atlanta says:

    I came across this article from the google news feed. I haven’t seen credentials to convince me that you have the competence to critique scientific studies and evaluate their conclusions on an important subject that caused millions of deaths around the world.

  • Joni Boulware says:

    I believe this study is absolutely telling us what we ought to know. Ordinary people and children don’t know how to replicate the mask effectiveness that “might” be achievable by trained medical personnel. However, that is debatable as masks have absolutely not kept nursing home patients protected.
    I observe idiotic behavior in mask wearing like taking it off, crumpling it up with hands and stuffing it into a pocket for reuse. The constant fiddling with the masks puts our hands on our noses and eye areas. Using a mask in an on and off manner such as when eating and drinking is also counterproductive. But bottom line, we humans are too trusting that the masks are our shield and we have returned to sta dunt to close to too many people for too long. Sooner or later we inhale the virus that is hanging in the air. The closer we stand the more we likely take in.
    I was much more careful when all that was protecting me was my good sense and my front door.

  • Kevin Roche says:

    luckily for me, I am not concerned about what you think about my “credentials” and you are free to go elsewhere and read only stuff that completely comports with the Beliefs, and they are just that, that you have

  • Kevin Roche says:

    Okay, it is fascinating to me how the moment this study comes out, well actually the moment people realized what its findings would be when it finally got published, the messaging immediately went to “oh, but masks are all about source control”. Go way back to the start and look at all the CDC stuff on masks. Forget this study, just use some common sense, how would a mask stop the same thing coming in but not going out. And pay attention and go read the studies I posted on long ago describing what happens to droplets when wearing a mask–they collect, they get broken up, eventually smaller particles, fully capable of carrying virus, get pushed through the mask. Cloth is the worst, surgical masks are better, N95s are almost completely protective. And none of that considers the gapping and other wearing issues. Exhalation pressure on average is higher than inhalation pressure. And for God’s sake, look around at mask wearing behavior and case curves everywhere and tell me how you possibly think that masks have made an impact on transmission.

  • Justin Case says:

    About Masks:
    Covid-19 virus particle size averages 125 nanometers (0.125 microns); the range is .06 microns to .14 microns; one needs an electron microscope to see a Covid-19 virus particle. The hoarded N95 mask filters down to 0.3 microns. So, N95 masks block few, if any, virus particles. This is a simple fact.
    To put this into perspective, it’s like putting up a chain link fence to keep mosquitoes out of your yard.
    (or, depending on your reasons for wearing a mask, a fence to prevent mosquitoes from leaving your yard)

    Please visit the Association of American Physicians and Surgeons for supporting information regarding virus and particle sizes.

    Other surgical masks, home-made masks and bandanas do the following:

    + allow free passage both ways of the virus particles.
    + they become a warm, damp reservoir of Covid-19 particles in asymptomatic “carriers” (estimated to be 85% of all people tested).

    For surgeons, years of training, intimidation, and humiliation teach them to touch nothing but their surgical field. Lay people constantly touch, re-arrange, and manipulate their “masks”, inoculating thousands of virus particles onto their bare or gloved hands. So, these masks encourage the transmission.

  • Joni R Boulware says:

    Truth. Masks cause lots of problems with lay persons. And kids? Joke.

  • HeineO says:

    We could end this whole debate by just asking President Trump to tell folks to wear masks 24 hours a day …

  • Ben richi says:

    As other comments have stated, this study only looked at the protective effect of masks (ie preventing mask users who are uninfected from getting covid) it did NOT look at source control which prevents infected asymptomatic people from transmitting it to others, which may be the most effective use of masks. There is another population study from Germany that shows a very significant reduction with mask mandates whose methods would also include source control.

    Mitze T, Kosfeld R, Rode J, Wälde K. Face masks considerably reduce COVID-19 cases in Germany. Proc Natl Acad Sci U S A. 2020 Dec 3:202015954. doi: 10.1073/pnas.2015954117. Epub ahead of print. PMID: 33273115.

    You have to be careful reading scientific literature and cherry picking summaries that justify your predetermined conclusions.

  • Kevin Roche says:

    Ummm, read your last sentence carefully, look in the mirror, go look at the curve of German cases, go look at the curve of every place that has had an extensive mask mandate and mask wearing wherever, say, oh, I don’t know, California. I think we know who has the predetermined conclusions and who actually looks at and analyzes data.

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