There are RCT for influenza and other diseases Sars (1):
https://pubmed.ncbi.nlm.nih.gov/22280120/
https://www.pnas.org/doi/10.1073/pnas.2014564118
While maybe we do not have the gold standard study, I think it was the right decision, given how little inconvenience masks have, for the much bigger benefit of reducing Covid risks.
There are RCT for influenza and other diseases Sars (1):
https://pubmed.ncbi.nlm.nih.gov/22280120/
https://www.pnas.org/doi/10.1073/pnas.2014564118
While maybe we do not have the gold standard study, I think it was the right decision, given how little inconvenience masks have, for the much bigger benefit of reducing Covid risks.