4 ms·

We have no evidence of positive effect. We have some evidence that they’re almost completely ineffective in the hands of the general public, some that they may

by irq11 6y ago

We have no evidence of positive effect. We have some evidence that they’re almost completely ineffective in the hands of the general public, some that they may be actively harmful (the only RCT ever performed with cloth masks showed that those who wore cloth masks were 13 fold worse off than those in the control arm), and some studies that show modest positive effects when N95 respirators are used by doctors in hospitals. If we are discussing “face covering” rules as enacted by governments today, which include everything from bandanas to paint respirators, then no, there is no supporting evidence.

EForEndeavour 6y ago
For someone demanding "evidence," you could stand to provide sources for your own claims. > the only RCT ever performed with cloth masks showed that those who wore cloth masks were 13 fold worse off than those in the control arm I think you're referring to this study, please confirm: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ "The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs)" You misrepresent the study in three critical ways: 1. You fail to note that the "control arm" was use of medical-grade masks, as opposed to no mask at all. 2. The study explicitly did not include a no-mask arm, as that would be ethically problematic. Their "control" arm actually consisted of "standard practice, which may or may not include mask use. Standard practice was used as control because the IRB deemed it unethical to ask participants to not wear a mask". The increased infection risk of cloth masks could be due to harm caused by cloth masks, benefit conferred by medical masks, or most likely both. As the authors point out, this study cannot determine this. 3. The study focused on healthcare workers, whereas the question at hand is whether convincing big portions of the general population to wear cloth masks in public enclosed spaces works. Fun fact: the same authors of this study have submitted a follow-up article which is available for early release: https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article They write that "wearing cloth masks should not be mandated for healthcare workers. In community settings, however, cloth masks may be used to prevent community spread of infections by sick or asymptomatically infected persons, and the public should be educated about their correct use." In other words: - the mask RCT you referred to doesn't support your agenda of insisting that community use of cloth masks doesn't mitigate the spread of respiratory illness - the same authors of that study have directly refuted your claims in an upcoming publication You aren't being downvoted because the left-leaning HN hivemind is reflexively jabbing the down arrow because you're telling them something they don't like. It's because you're flat-out wrong. > We have no evidence of positive effect. Demonstrably and categorically false. I'm starting to wonder if you're trolling HN on a Friday morning; if so, congratulations. If you aren't a troll, please review this body of literature helpfully curated by smart people who give a damn: https://masks4all.co/facts/ https://masks4all.co/facts/
- irq11 6y ago
  My link is from the Oxford Center for Evidence-based Medicine. Yours is a propaganda website made by a guy who teaches online ML classes. Jeremy Howard has no background in science or medicine, and his website consistently mischaracterizes the same data presented by CEBM. If you have to believe two different interpretations of the same data, prudence indicates that you should choose the interpretation coming from an expert. That said: 1) the study in question had a control arm of voluntary compliance with surgical masks. These are neither “medical grade”, nor was the compliance rate verified. 2) Regardless, it doesn’t matter: cloth masks were significantly more harmful than the control. 3) I agree that we should be careful to discriminate between studies of respirators, masks, “face coverings”, PPE and source control. So you should take the time to actually read the studies that Jeremy Howard cites. You’ll find that nearly all of the studies on masks are for respirators in medical settings, and that (as the CEBM link confirms, if you bothered to read it), the few studies of mask use by the general public have had ambiguous or negative outcomes. It isn’t even close: if you omit the studies conducted in medical settings, there’s almost no evidence for masks at all. 4) The CDC link isn’t a scientific article, it’s a review. Moreover the authors are clear that they are not contradicting their previous findings: ” To our knowledge, only 1 randomized controlled trial (4) has been conducted to examine the efficacy of cloth masks in healthcare settings, and the results do not favor use of cloth masks.” The authors are explicit that cloth masks are unsupported, possibly harmful, and only to be used as a last resort. You really should read the links you cite before you make strong claims about what they say.

by irq11 6y ago

EForEndeavour 6y ago

For someone demanding "evidence," you could stand to provide sources for your own claims. > the only RCT ever performed with cloth masks showed that those who wore cloth masks were 13 fold worse off than those in the control arm I think you're referring to this study, please confirm: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4420971/ "The aim of this study was to compare the efficacy of cloth masks to medical masks in hospital healthcare workers (HCWs)" You misrepresent the study in three critical ways: 1. You fail to note that the "control arm" was use of medical-grade masks, as opposed to no mask at all. 2. The study explicitly did not include a no-mask arm, as that would be ethically problematic. Their "control" arm actually consisted of "standard practice, which may or may not include mask use. Standard practice was used as control because the IRB deemed it unethical to ask participants to not wear a mask". The increased infection risk of cloth masks could be due to harm caused by cloth masks, benefit conferred by medical masks, or most likely both. As the authors point out, this study cannot determine this. 3. The study focused on healthcare workers, whereas the question at hand is whether convincing big portions of the general population to wear cloth masks in public enclosed spaces works. Fun fact: the same authors of this study have submitted a follow-up article which is available for early release: https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article https://wwwnc.cdc.gov/eid/article/26/10/20-0948_article They write that "wearing cloth masks should not be mandated for healthcare workers. In community settings, however, cloth masks may be used to prevent community spread of infections by sick or asymptomatically infected persons, and the public should be educated about their correct use." In other words: - the mask RCT you referred to doesn't support your agenda of insisting that community use of cloth masks doesn't mitigate the spread of respiratory illness - the same authors of that study have directly refuted your claims in an upcoming publication You aren't being downvoted because the left-leaning HN hivemind is reflexively jabbing the down arrow because you're telling them something they don't like. It's because you're flat-out wrong. > We have no evidence of positive effect. Demonstrably and categorically false. I'm starting to wonder if you're trolling HN on a Friday morning; if so, congratulations. If you aren't a troll, please review this body of literature helpfully curated by smart people who give a damn: https://masks4all.co/facts/ https://masks4all.co/facts/

irq11 6y ago
My link is from the Oxford Center for Evidence-based Medicine. Yours is a propaganda website made by a guy who teaches online ML classes. Jeremy Howard has no background in science or medicine, and his website consistently mischaracterizes the same data presented by CEBM. If you have to believe two different interpretations of the same data, prudence indicates that you should choose the interpretation coming from an expert. That said: 1) the study in question had a control arm of voluntary compliance with surgical masks. These are neither “medical grade”, nor was the compliance rate verified. 2) Regardless, it doesn’t matter: cloth masks were significantly more harmful than the control. 3) I agree that we should be careful to discriminate between studies of respirators, masks, “face coverings”, PPE and source control. So you should take the time to actually read the studies that Jeremy Howard cites. You’ll find that nearly all of the studies on masks are for respirators in medical settings, and that (as the CEBM link confirms, if you bothered to read it), the few studies of mask use by the general public have had ambiguous or negative outcomes. It isn’t even close: if you omit the studies conducted in medical settings, there’s almost no evidence for masks at all. 4) The CDC link isn’t a scientific article, it’s a review. Moreover the authors are clear that they are not contradicting their previous findings: ” To our knowledge, only 1 randomized controlled trial (4) has been conducted to examine the efficacy of cloth masks in healthcare settings, and the results do not favor use of cloth masks.” The authors are explicit that cloth masks are unsupported, possibly harmful, and only to be used as a last resort. You really should read the links you cite before you make strong claims about what they say.