...and then there's the smaller chance of touching an infected surface unknowingly and then rubbing one's face, rubbing the eyes etc. There's only so much that can be reasonably done to minimise risks. I remember being shocked/amused to see several travellers on my flight in March 2020 wearing a full paper suit with hood, N95 mask, gloves and goggles. They must have been very uncomfortable, especially if they needed the bathroom during the flight!