I got covid on Odyssey last January. I didn't know I had it until the day after I got home. I don't think anyone should be surprised if they get it on a ship. I think the elevators are traps. People crowd in and also seem to feel the need to talk which blows whatever is in their respiratory system into the air.
One thing that really annoys me no matter where I am is when people have a ridiculous need to whistle. Firstly, I can stand the sound and, secondly, again it blows whatever might be incubating in their respiratory systems that much further into the area.
It is going to be an interesting winter on the ships. We will see how the cruise lines handle it.