For point 1 above and point 2 below: to my knowledge this was widely already known by the medical community, and is widely used throughout asia to protect other

For point 1 above and point 2 below: to my knowledge this was widely already known by the medical community, and is widely used throughout asia to protect others against any cough or airborne diseases. Did the previous studies for flu only take into consideration the protecting value for the individual wearing it? How does the wearing of masks during the spanish flu fit into that? Was that not effective then? I guess its hard to say. It seems, well, obvious in hindsight surely, but you'd think that something this obvious in hindsight would be figured out by experts beforehand. Telling people actively to not wear masks seems like they not only missed the shot but were actively harmful.