Agree with all Janann's comments. I have cruised quite a lot before I had COPD.
Had superb vacations. Been on 2 where it was necessary for passengers to be taken off ship due to illness,in the Carabbean and Brazil. The crew and medical teams were excellant. 1 was airlifted to hospital and the second by road ambulance.
There are health risks of course on board ship but the crew are trained as are flight attendants on planes! As long as you discuss the trip with your Doctor,heed the advise. And make sure you have spare medications, just in case. I have 2 different inhalers and my doctor gave me a spare set so I could travel with 1 set in hold luggage and the other in my carry on.You should be fine. Plus emergency antibiotics don't forget to get from your GP.
I have recently travelled on my own from UK to USA, visiting family. Travelled internally by road for hundreds of miles and been fine. Made sure I washed my hands regularly ,carried hand sanitiser,ate well no junk food, well I did eat ice cream and donuts. Occasionally. Had a glass.of wine occasionally .
When I am in closed environments with loads of people I dab a drop or 2 of tee tree oil in my nostrils. Be positive and enjoy yourself. Have a great day.
COPD does not stop you living life, it's the bloomin infections. So keep healthy and HAPPY.