Study measuring viral particle shedding with an without surgical masks, with symptomatic people who are actually infected with influenza, rhinovirus (colds), and coronaviruses (also common colds).
Results: the masks didn't do very much for either influeza or rhinoviruses, and not enough people were infected with coronavirus to know if the results are valid.
@pete as far as I did read, results are more nuanced that what you are stating.
e.g. "Our findings indicate that surgical masks can efficaciously reduce the emission of influenza virus particles into the environment in respiratory droplets, but not in aerosols."
Mask are no panacea of course but they surely are helpful in some situations.
@roshii The sample size is not 26 for what they're trying to measure: most of their patients weren't producing detectable levels of viral particles to begin with, so those patients didn't generate any data about whether or not there was a decrease.
@pete as far as i read sample size was 26 for influenza, which you could argue depending on symptoms, but even with 2 you're kinda right: you can't draw conclusion from such a small sample size
https://www.nature.com/articles/s41591-020-0843-2/tables/2
yet, I'd prefer a surgeon to operate me with a mask :)