Here's my link, from people working to promote evidence-based medicine: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.n

Here's my link, from people working to promote evidence-based medicine: https://www.cebm.net/covid-19/masking-lack-of-evidence-with-politics/ https://www.cebm.net/covid-19/masking-lack-of-evidence-with-... From your link: > (eg, reusable 12–16-layer cotton masks; pinteraction=0·090; posterior probability >95%, low certainty That "low certainty" comes from GRADE. Low certainty in GRADE means "The true effect might be markedly different from the estimated effect". Masks may be very much better, or very much worse, than they estimate. The Interpretation section says this: > Robust randomised trials are needed to better inform the evidence for these interventions, but this systematic appraisal of currently best available evidence might inform interim guidance. Which suggests to me that they want more and better evidence. The end of the paper says this: > Our comprehensive systematic review provides the best available information on three simple and common interventions to combat the immediate threat of COVID-19, while new evidence on pharmacological treatments, vaccines, and other personal protective strategies is being generated. Physical distancing of at least 1 m is strongly associated with protection, but distances of up to 2 m might be more effective. 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. These sentences make me think the evidence isn't as strong as lots of people claim it is: > while new evidence on [...] other personal protective strategies is being generated. > Although direct evidence is limited > action is needed at all levels to address the paucity of better evidence.