Twenty-seven people aboard a Carnival cruise that reportedly departed from Texas tested positive for COVID-19 just before the ship made a stop in Belize City this week, according to the Belize Tourism Board.

The positive cases were among 26 crew members and one passenger on the Carnival Vista, which is carrying over 1,400 crew and nearly 3,000 passengers, the board said in a statement. The ship arrived Wednesday in Belize City.

All 27 were vaccinated, had mild or no symptoms, and were in isolation, according to the statement. The tourism board said 99.98% of the ship’s crew was vaccinated, as well as 96.5% of its passengers.

The Washington Post reported Carnival said it announced last week that there were positive cases on board, but the cruise line did not not give specific numbers. The ship left from Galveston, Texas, according to the Post.

Frequent setting for disease outbreaks

Cruise ships are often settings for disease outbreaks because of their closed environment and close contact between travelers from many countries, according to the CDC. An extensive list of preventative measures recommended by the agency to cruise ship operators includes minimizing the number of crew members sharing a cabin, eliminating in-person or group staff meetings and practicing social distancing. 

However the CDC notes in its recommendations that “Some measures are not necessary for crew who are fully vaccinated.”

Carnival is requiring passengers to be vaccinated, though there are exceptions for children and people with medical issues. The Miami-based cruise line company said in a statement August 4 that passengers must wear a mask in certain indoor areas, and provide a negative COVID test within three days of embarkment for cruises beginning August 14.

Carnival and other cruise lines were granted permission by the CDC in April to resume sailing in U.S. waters by mid-summer so long as 95% of customers and 98% of crew are vaccinated against COVID-19. Major cruise lines halted excursions from the U.S. in March of last year, when the CDC issued a “no-sail” edict that barred passenger cruise ships from leaving domestic ports.  

Carnival said it lost more than $2 billion in the quarter ended May 31 and has lost more than $14 billion since the coronavirus’ spread began. Meanwhile, its No. 2 industry rival, Royal Caribbean, has reported $1.1 billion in losses for the first quarter of 2021 and $5.8 billion in total losses for 2020.

Royal Caribbean’s Celebrity Edge vessel in June was the first cruise ship to board passengers at a U.S. port since in 15 months, a symbolic stride toward normalcy at risk of being upended by the Delta variant.

The CDC said on its website that it had investigated the Carnival Vista situation and the ship remains under observation.

Kristopher Brooks and Kate Gibson contributed to this report.