I think it is difficult to do a RCT of Covid (many different variants, vaccines, variability in symptoms), but it is a very fair point. Thank you. There are RC

I think it is difficult to do a RCT of Covid (many different variants, vaccines, variability in symptoms), but it is a very fair point. Thank you. There are RCT for influenza and other diseases Sars (1): https://pubmed.ncbi.nlm.nih.gov/22280120/ https://pubmed.ncbi.nlm.nih.gov/22280120/ https://www.pnas.org/doi/10.1073/pnas.2014564118 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.