3 ms·

Finding one of those studies would have taken you way less time that typing your comment. So I think we can all safely assume you are not asking this question i

Finding one of those studies would have taken you way less time that typing your comment. So I think we can all safely assume you are not asking this question in good faith, and you wouldn't believe one such study anyway.

DanBC 6y ago
Parent post is right though, we don't have good evidence for mask wearing. Here's a recent, high quality, paper in a high impact paper. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31142-9/fulltext https://www.thelancet.com/journals/lancet/article/PIIS0140-6... > Although direct evidence is limited, the optimum use of face masks, in particular N95 or similar respirators in health-care settings and 12–16-layer cotton or surgical masks in the community, could depend on contextual factors; action is needed at all levels to address the paucity of better evidence. Eye protection might provide additional benefits. Globally collaborative and well conducted studies, including randomised trials, of different personal protective strategies are needed regardless of the challenges, but this systematic appraisal of currently best available evidence could be considered to inform interim guidance. There's a bit to unpack here. 1) I don't know anyone wearing a 12 to 16 layer cotton mask. At best they're wearing 4 to 6 layers of cotton. Most people have maybe two layer masks. 2) "paucity of better evidence" isn't how I'd describe something that has great evidence. Look at how that paper describes the evidence for distancing vs masking: > Our search identified 172 observational studies across 16 countries and six continents, with no randomised controlled trials and 44 relevant comparative studies in health-care and non-health-care settings (n=25 697 patients). Transmission of viruses was lower with physical distancing of 1 m or more, compared with a distance of less than 1 m (n=10 736, pooled adjusted odds ratio [aOR] 0·18, 95% CI 0·09 to 0·38; risk difference [RD] −10·2%, 95% CI −11·5 to −7·5; moderate certainty); protection was increased as distance was lengthened (change in relative risk [RR] 2·02 per m; pinteraction=0·041; moderate certainty). Face mask use could result in a large reduction in risk of infection (n=2647; aOR 0·15, 95% CI 0·07 to 0·34, RD −14·3%, −15·9 to −10·7; low certainty), with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar (eg, reusable 12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%, low certainty). All of the mask evidence says "low certainty". That's from GRADE, and it means "low certainty (our confidence in the effect estimate is limited; the true effect could be substantially different from the estimate of the effect);"
tboyd47 6y ago
For your information, I was asking to expand my own knowledge on the subject. Top level commenter was adamant that masks were effective, so this being HN, where people typically know what they're talking about, I assumed they had a good reason to think that way. I have researched this a great deal myself, and have not found anything except flawed or inconclusive studies, like the majority of links submitted in this thread. Have a great day.

DanBC 6y ago

Parent post is right though, we don't have good evidence for mask wearing. Here's a recent, high quality, paper in a high impact paper. https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31142-9/fulltext https://www.thelancet.com/journals/lancet/article/PIIS0140-6... > Although direct evidence is limited, the optimum use of face masks, in particular N95 or similar respirators in health-care settings and 12–16-layer cotton or surgical masks in the community, could depend on contextual factors; action is needed at all levels to address the paucity of better evidence. Eye protection might provide additional benefits. Globally collaborative and well conducted studies, including randomised trials, of different personal protective strategies are needed regardless of the challenges, but this systematic appraisal of currently best available evidence could be considered to inform interim guidance. There's a bit to unpack here. 1) I don't know anyone wearing a 12 to 16 layer cotton mask. At best they're wearing 4 to 6 layers of cotton. Most people have maybe two layer masks. 2) "paucity of better evidence" isn't how I'd describe something that has great evidence. Look at how that paper describes the evidence for distancing vs masking: > Our search identified 172 observational studies across 16 countries and six continents, with no randomised controlled trials and 44 relevant comparative studies in health-care and non-health-care settings (n=25 697 patients). Transmission of viruses was lower with physical distancing of 1 m or more, compared with a distance of less than 1 m (n=10 736, pooled adjusted odds ratio [aOR] 0·18, 95% CI 0·09 to 0·38; risk difference [RD] −10·2%, 95% CI −11·5 to −7·5; moderate certainty); protection was increased as distance was lengthened (change in relative risk [RR] 2·02 per m; pinteraction=0·041; moderate certainty). Face mask use could result in a large reduction in risk of infection (n=2647; aOR 0·15, 95% CI 0·07 to 0·34, RD −14·3%, −15·9 to −10·7; low certainty), with stronger associations with N95 or similar respirators compared with disposable surgical masks or similar (eg, reusable 12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%, low certainty). All of the mask evidence says "low certainty". That's from GRADE, and it means "low certainty (our confidence in the effect estimate is limited; the true effect could be substantially different from the estimate of the effect);"

tboyd47 6y ago

For your information, I was asking to expand my own knowledge on the subject. Top level commenter was adamant that masks were effective, so this being HN, where people typically know what they're talking about, I assumed they had a good reason to think that way. I have researched this a great deal myself, and have not found anything except flawed or inconclusive studies, like the majority of links submitted in this thread. Have a great day.