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A New Study Shows Why Mask Mandates Will Always Be Doomed to Fail
A Greatly Anticipated Randomized Trial on Community Mask Use Illustrates Why Some People Are Confused About the Effect of Mask Mandates
Welcome to my newsletter, where I will feature my investigative reporting and commentary on science, technology, media, children, schools, psychology, and other topics.
I plan to post biweekly roundups of interesting articles, studies, and oddities, and will publish occasional investigative and reported pieces, such as the one below.
My reporting for New York magazine, the Atlantic, the Free Press and other publications will continue. (A list of some of my recent writing is here.) I am also still hard at work on my forthcoming book, An Abundance of Caution. Subscribers will get perks of some sort related to the book, which, alas, is not due out for another year (it’s going to be a BIG book).
Best, and thanks for reading,
Most of society has moved on, so if you’re not following the issue closely it may surprise you that mask mandates are still being reintroduced, as late as December and January, in numerous cities –– from Ann Arbor to Boston to Philly –– and almost always exclusively in schools. The rationale behind these mandates, of course, is that officials believe this will help reduce transmission of Covid. And, increasingly, influenza, RSV, and any number of other infectious viruses are also mentioned as worthy targets of mask requirements. Since Covid nor any of these other viruses are ever going away, it seems likely that neither will calls for mask mandates in certain pockets of the U.S.
Setting aside whether, in 2023, trying to mitigate the spread of these viruses through compelled action is an appropriate policy goal, the mandates are misguided for a more fundamental reason: Though masking on an individual level can be effective in specific circumstances, there is no convincing evidence of any meaningful benefit of mandates, which are a population level intervention.
This difference might seem confusing at first. But mandates are based on a lack of understanding about the gulf between the theoretical and the actual, and about human behavior. The results from a new, greatly anticipated study –– a large, randomized trial of mask use, in Guinea-Bissau –– help illustrate this critical point in a surprising way.
But before we get to the new study, some backstory about why it’s important.
Those who insist mandates are effective generally can only point to lab studies, which do not tell us how masks perform in the real world, and to observational studies that, by their very nature with uncontrolled and unknown variables, are often unreliable. The most cited studies that purport to show a benefit of school mask mandates, an area I have extensively investigated, are also rife with methodological flaws and errors. Lastly, these types of studies inherently depend on the subjective choices made by the researchers, such as when the study begins and ends, and who is in the study, which also casts doubt on their conclusions –– for example, the benefit of school masking that a CDC study found was wiped out in a more robust re-analysis that simply added more participants and a longer time period.
While also imperfect, randomized controlled trials, where participants or groups are randomly assigned to either receive the intervention or not, are designed to avoid a lot of these pitfalls, offering what is generally the highest quality, or “gold standard,” of evidence. During the pandemic there have been only three randomized trials on masking. One, in Denmark, did not find a statistically significant difference between the group that had recommended surgical mask use and the control. The other, in Bangladesh, found a difference of just 20 cases out of more than 300,000 individuals over 8 weeks between villages provided masks and also encouraged to wear them versus the control villages. It also did not include children. A third RCT on masks, published in December 2022, assessing the difference in benefit between surgical masks and N95 respirators in healthcare workers did not find a meaningful difference between them.
In addition to all this, it is crucial to note that prior to the pandemic, high level evidence of any benefit was similarly weak. In May 2020, the CDC published a review of 10 randomized trials on community masking’s effect on influenza rates. The agency’s report explained that although mechanistic evidence (often demonstrated by lab studies) suggested a benefit of masks, the trials on humans in the real world found masks “did not support a substantial effect on transmission.”
The results from the study, eagerly awaited since its inception in summer of 2020, out now in preprint, found among the more than 39,000 participants no statistical difference of Covid symptoms between the control group and the intervention group that was provided cloth masks.
At a glance, the Guinea-Bissau study is disappointing, as it wasn’t designed to directly answer the question at the heart of the debate –– the effect of mandates –– and instead merely looked at the impact of supplying people with cloth masks. But, pulling the lens back, it actually does tell us what we ultimately want to know. The study found that 99% of participants, regardless of whether they were in the intervention or control group, reported facemask use, and 92% said they wore a mask whenever they left home. Yet observed use of masks, by a member of the study team, was only 40%, with a 3% difference between the groups –– all this was while masks were mandated in the country.
What does this tell us? First, how people answer a survey about their behavior is different from their actual behavior. Second, humans tend to be really bad at complying with something they don’t want to do. And wearing a piece of material over your face is not something most people do with any fidelity for an extended duration of time.
Even the most ardent mask supporters, who want to wear them properly, fail to do so. And, as this study and others illustrate, even when masks are required they are either not worn properly, or not worn at all by a significant number of people. These images from a NY Times article comically show that children are no exception to this problem. And nor are teachers — this study, published by the CDC, on a school outbreak encapsulates the problem quite well: “the teacher read aloud unmasked to the class despite school requirements to mask while indoors.”
Succinctly, Benjamin Recht, a statistician at UC Berkeley, who co-authored a re-analysis of the Bangladesh RCT, which negated that trial’s findings, said: “At this point, I doubt any study will change anyone’s mind about masking. But the one consistent finding of all of the randomized studies is that the effect of this intervention at the population level is vanishingly small.”
Back in the summer of 2020, then-CDC director Robert Redfield said, “If all of us would put on a face covering now for the next 4-6 weeks, we could drive this epidemic to the ground.” His sentiment exemplifies the problem with how so many public health professionals think about interventions. Weltschmerz, one of those wonderful German words that articulates a peculiarity of the human condition, describes the sadness over the gulf between the way one wishes the world would be and how it actually is. If only people would stop behaving like people.
“The benefit of the Guinea-Bissau trial is that, to some extent, it's what happened in the real world,” said Westyn Branch Elliman, an infectious diseases physician at Harvard Medical School, and a specialist in implementation science. “There was a mandate, and in this study they made sure people had access to masks, and yet the trial found no difference between groups. We can argue about whether that's because of behavior or mask quality,” she said, “but to some extent it doesn't matter. No reasonable person would argue that masks work if you don't wear them. And most humans are not good at wearing them.”
Though randomized trials, in their ideal form, generally provide the highest form of evidence, like other studies, they, too, can suffer from methodological problems and limitations. The four RCTs on masking during the pandemic are no exception. But we have to acknowledge: if none of the masking RCTs during the pandemic found a meaningful benefit, and the systematic reviews of RCTs prior to the pandemic were similarly unimpressive, mandating this intervention was never, and is unlikely to ever be an effective policy.