Your own link contains references to multiple peer-reviewed studies on mask-wearing. And of course there have been more studies done in the ~18 months since that article was published.
"For now, Osterholm, in Minnesota, wears a mask. Yet he laments the “lack of scientific rigour” that has so far been brought to the topic. “We criticize people all the time in the science world for making statements without any data,” he says. “We’re doing a lot of the same thing here.” "
Peer review does not mean proof of efficacy as the above quote shows. read the studies.
Almost all references are from 2020.
April 2020 BMJ
2In their editorial to the BMJ,[1] Greenhalgh et al. advise that surgical masks should be worn in public to prevent some transmission of covid-19, adding that we should sometimes act without definitive evidence, just in case, according to the precautionary principle. The Authors quote a definition of the precautionary principle found on Wikipedia, “a strategy for approaching issues of potential harm when extensive scientific knowledge on the matter is lacking.” "
Most other article on the BMJ site seem to be focus on downside a gender and race not the efficacy of the mask wearing itself.
https://www.bmj.com/content/350/bmj.h694
2015
"The lack of research on facemasks and respirators is reflected in varied and sometimes conflicting policies and guidelines. Further research should focus on examining the efficacy of facemasks against specific infectious threats such as influenza and tuberculosis, assessing the efficacy of cloth masks, investigating common practices such as reuse of masks, assessing compliance, filling in policy gaps, and obtaining cost effectiveness data using clinical efficacy estimates. "
Please note the use of the word 'respirators ' these are not cloth home made face masks or the surgical n95