Originally Posted by
jfsully
I think you are misinterpreting the results and conclusions here. First, to say that there is a "lack of compelling evidence" (their phrase) is very different from saying that something is "thought to be completely ineffective" (your phrase). If you look at the studies they cited, most found a trend toward the effectiveness of masks and handwashing, but they did not meet statistical significance. This suggests that there is probably a benefit, but that it may be small and/or perhaps it is hard to study. Several of the studies cited found evidence of good effect of masks and handwashing in secondary analyses where they focused on subsets where the compliance was known (ie they presumably had observed frequency of masks and handwashing rather than relying on self-report). Secondary subset analyses are generally less reliable than the primary outcomes, so these were not considered in the overall conclusions of the analysis. But I think this is not surprising. In our hospital, long before COVID, we found that observed hand hygeine was much lower than self-reported hand hygeine among doctors and nurses.
Of all the nonpharm interventions studied, masks and handwashing had the best evidence (their grade was "Moderate") for effectiveness. They did find some effectiveness with social distancing and strict travel restrictions as well, among other things. So in general, we would conclude that there is likely some benefit to doing these interventions, which should be weighed against the cost of doing it.
As far as I can tell, the downsides of masks are:
1. there is a small financial and time expense to using masks
2. masks make some people feel bad
The upside is that they probably provide some slowing to the spread of covid, flu, etc. So if you want this whole thing to be over, wearing a mask when you can't social distance makes sense.