There’s a lot of back and forth going on over a new study that people say suggests masks are useless to stop the spread of an aerosol based virus. The NY Times, which has been a bastion of COVID mitigation skepticism, featured an op-ed by Brett Stephens that’s as misleading as what you can find on Breitbart any given day. Here’s Dr Tom Friedan: Masks have been an effective tool throughout the Covid pandemic, despite erroneous claims to the contrary. The widely cited Cochrane review on masks was poorly done and even more poorly communicated. Regrettably, researchers analyzed the wrong datasets, in the wrong way, and overstated their conclusions—leading to sweeping and inaccurate characterizations. Many nuances around mask type, setting, behavior, and policy are explained in this helpful piece by @dr_kkjetelina. http://bit.ly/3ErwuNN 3/ The CDC did an excellent review citing extensive evidence that masks are effective, from multiple studies. http://bit.ly/41oDV1W Vox also provided a good sense of some of the biases and inaccuracies in the Cochrane review and the idiosyncrasies of the lead author: http://bit.ly/3kr4jaX Although randomized controlled trials (RCTs) are extremely important, especially for many clinical questions, they are not the best method for every scientific question, as I outlined in @NEJM several years ago: https://bit.ly/3m5ZvYM The question of WHAT masks are being used for needs to be assessed. Where most transmission is in the household and masks aren’t worn in households, then they cannot be expected to prevent that transmission. What also needs to be assessed isn’t whether…