People were not wearing masks en masse last autumn. Infact, I rarely saw anyone other than really elderly people in them. Social distancing or dare I say it, your own immune system probably did the job as opposed to the masks.No, tshirt material and cotton are ineffective. KN95s are proven much more effective at preventing covid transmission under peer reviewed studies, and I avoided it for two years until my neighbour caught it (we share a hallway, and I don't usually mask up in the hallway). I wear kn95s now.
I will say that even the thin masks did wonderfully at preventing me from catching a cold at back to back conventions in the autumn when I was meeting upwards of 300+ people a day, events I normally get an awful cold or flu from. So that was a nice side effect.
I see no reason why the hospitals still insist on people wearing those surgical paper masks. Their only purpose is to stop unpleasant bodily fluids going into orifices on the face during procedures - surely the staff working there must know this but still insist!