| In healthcare there's a bunch of stuff that sounds plausible, and then we do the research, and we find that it doesn't help or it causes harm. Evidence based medicine isn't there to stop crystal healing. It's there to work out whether knee arthroscopy is better than placebo. (For some patients it isn't). Masks have a plausible mechanism of action. But they also have plausible mechanisms of harm: they may reduce social distancing; people touch their face more often when wearing a mask; most people don't know how to put on or take off the masks; most people don't have a safe place to store the mask when it's not being worn; etc. We don't know if the benefits outweigh the risk, because we don't have good quality evidence yet. Here's some papers: https://www.thelancet.com/journals/lancet/article/PIIS0140-6... > 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). Here they say that distancing does work. But when talking about N95 masks they only say "could" work, and for cloth masks they say they have low certainty. Later in the paper they say they need more and better evidence for masks. https://www.publish.csiro.au/hc/pdf/HC15950 Have a look at the table on page 2. They've looked at RCTs and they've found no benefit for masks. They go back and look at other data and they claim to find a benefit, which is why masks are recommended for HCPs. When you say "it's transmitted by inhaled droplets" you didn't say how it's caught, and here it's clear that you think it's by breathing in those droplets. That's one route. The other is via the eye. Or the droplets land on surfaces and are transferred by hand to the eye or nose or mouth. https://www.cmaj.ca/content/188/8/567 > Transmission of acute respiratory infections occurs primarily by contact and droplet routes, and accordingly, the use of a surgical mask, eye protection, gown and gloves should be considered appropriate personal protective equipment when providing routine care for a patient with a transmissible acute respiratory infection. When someone coughs the droplets are expelled in a range of sizes. Some of these are trapped by cloth masks, but not all. https://www.cidrap.umn.edu/news-perspective/2020/04/data-do-... |