There is no good evidence showing that masking slows the spread of SARS-COV-2 because wealthy nations like the USA failed to use the opportunity of the pandemic

There is no good evidence showing that masking slows the spread of SARS-COV-2 because wealthy nations like the USA failed to use the opportunity of the pandemic to conduct large scale randomized controlled trials testing their efficacy. The positive studies that everyone is referencing are all observational studies subject to confounders. For instance, the people that comply with mask mandates probably do other things that slow the spread of the virus, like washing their hands. It's impossible to control for all confounders without a priori randomization. That is why RCTs were invented, why they are the "gold standard" of evidence, and why they are the only type of study included in the systematic reviews done by Cochrane. When the RCTs are systematically reviewed the effect of masks disappears. This is the infamous "Cochrane study" you'll read about. This review is conducted periodically, it has been done six or seven times in the last 20 years, and has failed to find evidence of masks/respirators slowing the spread of any respiratory viruses. However, this same review shows that hand washing slows the spread of the COVID virus. [0] Maybe masking works but there just isn't the evidence available to say that it does. All medical interventions have a cost and it shouldn't be paid by the public without good evidence that it will be worth it. This video is an excellent discussion of the controversy with the lead author of the Cochrane review of physical interventions to interrupt or reduce the spread of respiratory viruses and another epidemiologist from the "Evidence Based Medicine" movement which discounts observational studies. They discuss the evidence including the "Bangladesh RCT," the precautionary principle, equipoise, the reaction to the latest review as compared to previous ones and the actions of Cochrane's director. [1] [0] https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD006207.pub6/full https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD... [1] https://www.youtube.com/watch?v=P_JTBftjQuA https://www.youtube.com/watch?v=P_JTBftjQuA