My parents are leaving Saturday for a cruise from Puerto Rico. They have received documents from the cruise company that no one who has been in Hong Kong or China in the last month will be allowed on board. Neither will anyone with a fever, and that they will be checked at boarding by medical staff. The cruise company is going by passports and offering full refunds and credits on future cruises for those barred. Unfortunately there isn't a way to tell who was coughed on by someone in the airport on their way to the cruise by someone who was in Hong Kong or China, but give the company credit for taking some dramatic, and expensive, steps. I think they realize their industry is under the microscope.
My parents are a bit concerned, but they are still going. They did say that if it was an Asian area cruise, which they have done in the past though not in a year or two, they would not go. But they feel comfortable with the odds on a Caribbean cruise. I tend to agree, though at their ages I might be more concerned than mine.