Cruises have a high percentage of high risk passengers. Higher than the general population.
Flu = 14 hospitalizations and 1.2 deaths per 1000 people
Corona according to Oxford = Less than 1 hospitalization and 0.1 deaths per 1000 people
The US population of 62+ is about 15%, or 150/1000. Let’s pretend the boat has 75% above 62, including all the crew mates and everyone is infected. We end up with about 4-5 hospitalizations and 0.5 deaths/1000. Multiply by 3.7 (cruise capacity is 3,700) and you have 18 hospitalizations and 1.8 deaths/1000.
So even the most wildest exaggerations of the elderly population and infected count, were still 6-10x lower than reality.