The demand for a randomized trial proving the benefits to mask-wearers rests on one of the most important but least understood facts about why we started recommending masks in the first place: to prevent disease transmission to others. Mask-wearing is not an individual benefit, it’s a community benefit. Further, this discussion reveals some of the underlying reasons for our feeble response to this pandemic: reasons that go beyond the obvious and many failures of the OUTGOING (!) administration.
To have a proper study for masks for source-control, we’d need to enroll communities and do a cluster randomized study—comparing communities, not just individuals. That is both difficult and also with much less explanatory power than one would hope since pathogen is also overdispersed: some people get hit badly by the disease just by chance. That makes causal inference harder.
In reality, while opposing masks has now become an ideological component of pandemic-denialism, some the problems I outline above permeate not just supporters of this president, but much of Western medical establishment as well. This is also why the instruction to “just follow the science” isn’t enough to address this pandemic. Yes, we should absolutely follow the science, but here’s the awful truth: we do not have a “science” that is fully up to the challenge, especially when it comes to understanding the intersection between human behavior and the pandemic, and the many complications and twists of the failings of our expert communities and how they relate to society. That task remains ahead of us.