From a February 12, 2019 Norwegian Cruise Line travel alert:
Any guest that holds a Chinese, Hong Kong, or Macau passport, will be unable to board any of our ships, regardless of residency. (Except U.S. Alien Residents holding an Alien Resident Card (ARC), also known as a “Green Card” traveling on itineraries that sail from a US port and end in a US port.)
Any crew members joining our ships that hold a Chinese, Hong Kong or Macau passport will not be allowed to board our ships. In addition, any crew members who have traveled from, visited or transited via airports in China, including Hong Kong and Macau within 30 days will not be allowed to board our ships.
Guests who have traveled from, visited or transited via airports in China, including Hong Kong and Macau, within 30 days of their voyage embarkation, regardless of nationality, will not be allowed to board any of our vessels. The standard incubation period recognized by the WHO and U.S. CDC for this virus is 14 days. Guests who are denied boarding will be issued a refund when they provide proof of travel.
Norwegian Cruise Line serves 2.4 million passengers a year.
Not a great time to book a cruise.