Noro is very nasty but I’m not worried. IME more un-hygenic people pass through a Wal-Mart in 2 days then a cruise ship in 5. I also pack contingency medicines for just such an issue.
I’m in W. Central FL and it’s Spring Break, i.e, global pathogens’ yearly convention. 3 weeks ago had a co-worker go from “out sick” to “died of MRSA and staph last night” in just 9 days. Gotta be prepared.
The only thing I would say is that you are obviously quite conscious about the whole issue.
*Most* people get on these boats with the idea of shutting their brains off and most get into that state. That’s good, that’s what vacations are for and that’s what the cruise line wants you to do so you blow money on gambling and drinks.
My only point is that if the one thing you can remember aboard such a ship is to wash your hands assiduously and frequently, it WILL, with perfect certainty, lower the odds of a truly rotten experience. And it’s not necessarily obvious, because the ships are pretty much done up like really high end hotels where “Geez I gotta wash my hands” isn’t exactly your first thought.