It seems outrageously wrong to me to summarize that Lancet article by saying "We have lots of RCTs on mask wearing (mostly in healthcare professionals) and they

It seems outrageously wrong to me to summarize that Lancet article by saying "We have lots of RCTs on mask wearing (mostly in healthcare professionals) and they struggle to find a benefit." or "I've read the actual studies. They don't show benefits". The Lancet article looks at dozens of studies of the relationship between mask-wearing and infection with coronaviruses. (Some SARS, some MERS, some COVID-19.) Those studies fall, without exception, into the three following categories. 1. A few saw no cases of infection with or without masks, and therefore tell us nothing about whether masks help and how much. 2. One saw no cases of infection with masks and just two without masks (in a fairly small sample). It somehow manages to report a relative risk of 1.03 for wearing masks (!), which I can only assume is the result of some statistical adjustment that doesn't quite make sense in this case. (The real conclusion from this one is: "This study doesn't provide enough data to draw any conclusions.") 3. In every single one of the others, wearing a mask was associated with lower probability of infection. Some of the studies weren't powerful enough for the difference to be (on its own) statistically significant, but all of them pointed in the same direction and the underpowered ones had relative risk point-estimates similar to those of the not-underpowered ones. Sure, they report this as "low certainty" because, e.g., none of these studies was a proper randomized controlled trial. Sure, we would do well to get more data. But I see no possible way to characterize what it says in the ways you have. They don't "struggle to find a benefit". They readily find a very considerable benefit. They don't "not show benefits". They absolutely do show benefits. There are issues: we don't have e.g. nice big RCTs where someone has somehow contrived to have two otherwise identical large populations of the general public make different mask-wearing choices, and that means that there is inevitably some uncertainty in applying the results to the question of what benefit there is from getting the public to wear masks. But it 's pure grade-A bullshit to say that the studies "don't show benefits".