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Michael DAmbrosio's avatar

I'm still fascinated by the psychology and group dynamics that allowed the entire world to do a complete 180 on masks, to completely abandon the scientific method, seek out the weakest of evidence to support our superstitions we embraced out of nowhere.... it really was like a new Dark Age swept over us in 2020. I'm still in awe by it. There's a certain magic of being able to witness this first hand, as I ignorantly assumed we were "better than that". The superstition phase of medicine, whether it was bloodletting, electroshock, lobotomies, mercury elixirs - all of that quackery could never arise again now that we had "science" and EBM to shield us from such irrationality.

It really is remarkable. I truly hope my grandchildren will think I am bullshitting them when I tell them about 2020 someday.

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David Scales's avatar

Very well written and clear - thank you! What I love about this one is the description of how a medical study is like a test, it doesn't provide certainty but it updates our priors. What is useful about this is that it allows us to see where the biases are, and, in this case, they're in the 'common sense' section, which pulls current anecdata about mask compliance to state the priors.

And what is clear is Mandrola's priors that "masks don't work" is coming from a place of selective evidence. But this framing is helpful to show that we don't disagree about this study or its conclusions. The bias is in our priors and what we choose to cite for 'common sense.' My "common sense" is the fact that I worked as a hospitalist during the first wave in NYC, wearing only surgical masks for the first week, spending hours in rooms with patients, then n95s until that summer. Mask adherence was high among co-workers. The only healthcare workers I heard of that got sick were those who ate in communal settings in breakrooms. It seems Cochrane's methodology of excluding observational studies is a big mistake here because it seems like those studies should at least inform our priors, even if we take that evidence with a grain of salt. 

The challenge with Cochrane reviews, as pointed out by Trish Greenhalgh, is they're insufficient for real world questions and challenges where policymakers may need to make decisions under high uncertainty and may lean toward precaution. Despite my various levels of immunity, in the absence of concrete evidence it seems reasonable to err on the side of caution and wear masks in certain settings. I still do because the risk of harm (to myself or others) is low while the possibility of benefit (to myself and others) seems to outweigh that.

What is worse is that this debate is playing out publicly. I appreciate Mandrola's nuanced take here, and the nuance of the study authors. But the problems arise in the press. Bloomberg, for example, dedicated their health newsletter to the issue this morning, and their takeaway was "masks don't work," framing a looming controversy with how long can Hong Kong's mask policy hold out since masks aren't shown to work?

The nuance, uncertainty and priors are lost in the translation from dissecting the study on its merits to the reporting on it in the press. And, what follows is the propagation of misinformation - overstating the conclusions of a study when even the study authors were quite circumspect and nuanced in how they reported it.

I struggle with this because this is exactly what we should be doing as scientists - debating the science, being transparent about our priors and how much any new study should update those. But channels are getting crossed as we debate this publicly and nuance is lost in translation, making the issue even more political. Which raises the questions, is this the proper place for this debate? Or is it better suited for a medical journal?  

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