No, it isn't. Because he's being generous: the 11% difference was on a baseline seroprevalence of 0.76%. So you have a study where cloth masks were shown to be completely ineffective, and the total absolute effect size of the surgical mask arm was .08% (edit: 0.09% per the numbers in the paper).
In other words: you'd have to get 1300 people to wear masks to prevent one seropositive (in case you're wondering, the confidence interval on that value overlaps zero.) No matter how you spin it, this is a small, small effect. And this is in a completely unvaccinated population -- the best possible scenario for masks.
Even if we accept the argument that "several times more" people would be protected if we lived in a fictional, ideal universe where everyone wore surgical masks (newsflash: we don't), we're still only talking about a total effect size of a fraction of a percent.
Oh and by the way, it's particularly hilarious that the paragraph you quoted says the following:
> Additionally, the intervention reduced symptomatic seroprevalence more when surgical masks were used
That has to go in my top-five lifetime examples of weasel-wording for reframing negative experimental outcomes. Cloth masks showed no effect. Saying that surgical masks reduced prevalence "more" is like saying that together, Ootani Shohei and I hit 46 home runs last year. But yeah, he hit more.
Wait a second.
> In other words: you'd have to get 1300 people to wear masks to prevent one seropositive (in case you're wondering, the confidence interval on that value overlaps zero.)
You are assuming 0.76% prevalence. This is, I assume, in specific point of time, but somehow, you extend this to long-term intervention.
If you spin COVID-19 "but only 0.5% of population is infected _right now_", any intervention will seem extremely ineffective. "Oh, you want to vaccinate 300 millions of people to prevent 2000 deaths" (without saying it's 2000 deaths _per day_).
I am not. I'm using the numbers from the paper to illustrate a point.
Even if seroprevalence was as high as 6% at any given time (which is about as high as it ever was in NYC, for example), an 11% difference is 0.66%, or 1 case per 152 people wearing masks. And that's in a fully unvaccinated population.
We're simply not talking about huge differences here. Certainly nothing close to a statistically meaningful difference in R0.
That's not accurate unless I'm missing something... sticking with just the surgical mask arm -- the effect size of 0.08% was based on a binary mask vs. non-mask intervention. It has no relation to the number of people masking. The intervention was getting more people to mask -- they succeeded mildly, where 6/10 people still hadn't masked. But that was sufficient for a 10% reduction in seropositive cases.
Edit;
They actually address this specifically;
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.
So for 51,000 people additional people wearing masks -- 1,600 people were spared Covid symptoms and 103 people were spared symptoms + seropostive diagnosis. This with only a total of 42% of people wearing masks and a relatively low level of underlying Covid.
It's an especially obvious intervention based on the exponential potential of Covid infection and early R0 of 6 or whatever it was, plus how effective the surgical masks were (especially in older age groups via Figure 3).
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.
I whole-heartedly don't understand this.. in the places with universal masking, there is essentially no Covid (most of Asia, even cities like SF). Surgical masks are obviously sufficient to prevent most infection in hospital and other clinical settings. There's evidence that even a small portion of people wearing them in public reduces the incidence of disease. And your takeaway is that it's mass hysteria to encourage an extraordinarily cheap NPI?
Just completely, utterly wrong. Japan had a huge spike this winter. Korea is currently at all-time highs. Vietnam is currently near all-time highs. Thailand peaked at 20,000 cases per day, and is currently at 10,000.
These numbers are lower than the US in absolute terms, but claiming "essentially no Covid" means only that you aren't informed of the reality of the situation. Covid is running rampant across Asia, even now.
> There's evidence that even a small portion of people wearing them in public reduces the incidence of disease.
There is literally no evidence of this. The few RCTs that have performed suggest the opposite: you have to put masks on a huge number of people (hundreds to thousands) to prevent even a single case.
> And your takeaway is that it's mass hysteria to encourage an extraordinarily cheap NPI?
No, my takeaway is that there's very little evidence supporting the use of masks. Because there isn't. And most of what there is, is of exceptionally low quality.
The major difference to Germany I see between the two countries in terms of measures, Japanese were masks (vaccinated) and Mask Wearing in Germany has become political as it did in the US.
He says;
> Interestingly, in the only published cluster RCT to date during COVID19, surgical masks had an 11% risk reduction and cloth masks had no effect at all on the primary endpoint of symptom driven lab positive result
The actual study showed that with intervention, the scientists increased the rate of mask wearing from 13% to 42% -- and that 29/100 person uptake was enough to reduce Covid seropresence by 11% in the community. That's a huge effect! Fewer than half of the people in the villages were wearing masks and symptomatic Covid saw >10% reduction compared to villages without extra mask wearing. It's abundantly clear that the effect would be far greater with universal masking so to say "mask wearing only leads to a 10% reduction" omits a massive part of the story.
https://www.poverty-action.org/sites/default/files/publicati...
To quote the authors who tried in vain to prevent people like Vinay from mangling their research:
> Our results should not be taken to imply that masks can prevent only 10% of COVID-19 cases, let alone 10% of COVID-19 mortality. Our intervention induced 29 more people out of every 100 to wear masks, with 42% of people wearing masks in total. The total impact with near universal masking–perhaps achievable with alternative strategies or stricter enforcement–may be several times larger than our 10% estimate. Additionally, the intervention reduced symptomatic seroprevalence more when surgical masks were used, and even more for the highest-risk individuals in our sample (23% for ages 50-60 and 35% for ages 60+). These numbers likely give a better sense of the impact of our intervention on severe morbidity and mortality, since most of the disease burden is borne by the elderly. Where achievable, universal mask adoption is likely to have still larger impacts.