An impressive randomised study from Bangladesh proves the effectiveness of #masks, we' re told.
poverty-action.org/publication/im…
I don't think it shows a dramatic effect at all.
It doesn't prove they don't either!
1/NN
poverty-action.org/publication/im…
I don't think it shows a dramatic effect at all.
It doesn't prove they don't either!
1/NN
There's plenty of evidence masks work (labs, simulations, epidemiology, observational studies) as summarised by @fredericadnet in his NL 58 @ fr.calameo.com/accounts/62827…
from jamanetwork.com/journals/jama/…
The Bangladeshi study's methodology is impressively serious + thorough, but
2/7
from jamanetwork.com/journals/jama/…
The Bangladeshi study's methodology is impressively serious + thorough, but
2/7
as too often in med. literature, they sugarcoat the results by expressing them as relative risks.
Seroprevalence in symptomatic patients was 0.68% vs 0.76% in treatment and control groups respectively.
They don't tell but the real result is ...
3/7
Seroprevalence in symptomatic patients was 0.68% vs 0.76% in treatment and control groups respectively.
They don't tell but the real result is ...
3/7
that the absolute (meaningful) risk reduction is 0.08%.
Period
Of course the relative risk reduction looks better: 11.2%
The other interesting result is that despite a very powerful campaign to get people to "properly" (nose and mouth covered) wear masks,
3/7
Period
Of course the relative risk reduction looks better: 11.2%
The other interesting result is that despite a very powerful campaign to get people to "properly" (nose and mouth covered) wear masks,
3/7
only 43% actually did so vs 13% in the control villages.
I observe (poor science 😬) a way higher percentage maybe 70 % in the places I live in, using their definition (covering face and nose). But in these 70% half the masks are miserably and massivley leaky because of
4/7
I observe (poor science 😬) a way higher percentage maybe 70 % in the places I live in, using their definition (covering face and nose). But in these 70% half the masks are miserably and massivley leaky because of
4/7
poor technique or will.
Another point is that only adults wearing masks (>18 yo) were numbered. Not clear what was asked and obtained from children and teenagers
I don't think infection incidence can be controlled if only adults wear masks.
ANother caveat is that covering
5/7
Another point is that only adults wearing masks (>18 yo) were numbered. Not clear what was asked and obtained from children and teenagers
I don't think infection incidence can be controlled if only adults wear masks.
ANother caveat is that covering
5/7
nose and mouth in't enough: leaks linked with miserable fit are so important ! The most frequent being aerosol nozzles at the cheeks because of the crossed elastic straps and unmoulded nose clips
Now there's also the type of mask that matters...
6/7
@jljcolorado @flahault
Now there's also the type of mask that matters...
6/7
@jljcolorado @flahault
@FLAHAULT @Don_Milton @EricBillyFR @Cote_Science @kakape @virginie_garin @P_Amouyel @HuffmanLabDU @linseymarr @jljcolorado @kprather88 @Andreotti_B @LacombeKarine1 @GilbertDeray @CorsIAQ @ARosencher @DavidPauget @LUppsala @nicolasberrod @helenerossinot @dseux @emma_ducros
7/7
7/7
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