So Carnival just sent an email out with this info:
Any guest who tests positive at embarkation, and their traveling companions in the same stateroom along with other close contacts, will not be able to cruise and will be provided a future cruise credit. (A close contact is any individual who has been within 6 feet of an infected/symptomatic person for a cumulative total of 15 minutes or more over a 24-hour period within 14 days prior to sailing.)
It sounds like anyone in the cabin even if they aren't close contacts would be barred from cruising even if they hadn't met before getting to the port?
Totally sucks if so.