Royal Caribbean’s Symphony of the Seas cruise ship, seen docked in Miami in March 2020, saw 48 cases of COVID-19 on its most recent seven-day sailing.

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Royal Caribbean’s Symphony of the Seas cruise ship, seen docked in Miami in March 2020, saw 48 cases of COVID-19 on its most recent seven-day sailing.

Joe Raedle/Getty Images

Forty-eight passengers and crew members tested positive for COVID-19 on a Royal Caribbean cruise ship that docked on Saturday in Miami.

The outbreak occurred on the company’s Symphony of the Seas ship, part of its line of Oasis vessels that are the world’s largest cruise ships. There were 6,091 guests and crew members on board at the time.

“Each person quickly went into quarantine. Everyone who tested positive was asymptomatic or mildly symptomatic, and we continuously monitored their health,” according to a statement from Royal Caribbean International.

The Miami Herald reports that at least one passenger had more significant symptoms. According to the newspaper, James Johnson of Orlando attested that his aunt “started feeling very ill with a sore throat and an ear ache and later developed a strong cough. After testing positive for COVID-19, Johnson said she only received an oxygen and temperature check and were told that medical staff was too overwhelmed to monitor her more closely.”

Asked about that report, Royal Caribbean spokesperson Lyan Sierra-Caro told NPR in an email, “all were asymptomatic or mildly symptomatic. We did not have any critical cases on board.”

Royal Caribbean says that six passengers left the cruise early and were transported home.

Miami marked the end of a seven-night cruise that began Dec. 11 with stops in St. Maarten, St. Thomas and a private island in the Caribbean that is owned by Royal Caribbean.

For cruises leaving from U.S. ports, Royal Caribbean requires all passengers ages 12 and older to be vaccinated with two doses of a COVID-19 vaccine, or one dose of the Johnson & Johnson vaccine. Passengers ages 2 and up must also show a negative test taken within two or three days of boarding.

The positive cases on the ship were identified after contact tracing a passenger who tested positive.

“The cruise sailed with 95% of the onboard community fully vaccinated, and 98% of those who tested positive were fully vaccinated,” according to Royal Caribbean.

The Centers for Disease Control and Preventions says it has investigated the Symphony of the Sea and the ship remains under observation.

After disembarking the passengers from the Dec. 11 cruise, the ship kept on its schedule. It’s now docked in Cozumel, Mexico, according to VesselFinder.