The RCT was a binary test of each kind of mask. Any other outcome is imaginary. There's no mathematical adjustment that can tell you what would have happened in the hypothetical alternative universe where everyone wore a surgical mask. That's just storytelling with numbers.
> But that was sufficient for a 10% reduction in seropositive cases.
No. It was a an 11% relative reduction, on a 0.76% seropositivity rate. The actual effect size was about 0.09% (I wrote 0.08% earlier, because I just divided the two numbers, and didn't use the figures from the paper). When you compare the cost of an intervention to the benefits, you use the absolute effect size, because you don't pay relative costs for your interventions (e.g. is it worth forcing every toddler in the world to wear a mask while sleeping for a "huge" 66% relative risk reduction from 0.0000003% to 0.0000001%? Probably not unless you're a crazy person. The costs vastly outweigh the benefits, even though the "relative" benefit is strong.)
> Our estimates suggest that mask-wearing increased by 28.8 percentage points, corresponding to an estimated 51,347 additional adults wearing masks in intervention villages, and this effect was persistent even after active mask promotion was discontinued. The intervention led to a 9.3% reduction in symptomatic SARS-CoV-2 seroprevalence (which corresponds to a 103 fewer symptomatic seropositives) and an 11.9% reduction in the prevalence of COVID-like symptoms, corresponding to 1,587 fewer people reporting these symptoms.
This is garbage. They're combining the two mask arms and claiming a combined effect size, even though the cloth mask arm was shown to have no effect. You can't do that. They're spinning like crazy to hide a weak outcome. They also don't report the raw numbers for the arms, and they don't dwell too much on the fact that "distancing" increased in the mask villages over the controls. That could easily swamp the measured effects. But I digress.
The surgical mask villages had 106,201 people, and an 11.2% relative reduction in seroprevalence, from 0.76% to 0.67%. The cloth mask villages saw essentially no difference at all: 0.76% vs 0.74%
There's simply no way to look at this data as anything than incredibly weak evidence for masks. I honestly can't believe we're fighting about something that makes, at best, a tiny fraction of a percent difference in outcome. Mass hysteria.