The CDC has 75 different cruise ships under some form of investigation, observation or monitoring due to COVID outbreaks onboard, the agency said.
The data update, posted late Monday night, underscores the difficulty in controlling the virus in the face of the highly contagious omicron variant, particularly given its increased ability to infect vaccinated people.
There are 36 ships under active investigation, 32 where the CDC investigated already and the ship remains under observation, and 7 where the CDC is monitoring but the ship is under the threshold for investigation. The status table did not indicate how many people were infected on each ship, or when.
To meet the investigation criteria, a ship on a so-called restricted voyage (operating under provisional CDC guidelines) has to have infections in 0.1% of passengers over the prior seven days, or at least one case among crew.
The limits are higher for "simulated" or "crew-only" cruises, where there are few if any passengers and the trip duration is shorter.
In just the last few days, some passengers on a luxury cruise to the Caribbean had to disembark and isolate in New York City after positive tests, another ship was denied docking in Mexico after dozens of crew members tested positive, and a third ship docked in New Orleans with multiple infected passengers after a cruise.