Four dozen people aboard a Royal Caribbean cruise ship tested positive for coronavirus when they returned to Miami on Saturday following a seven-day excursion, a report said.

All but one of those infected on the Symphony of the Seas was fully vaccinated, the cruise line said in a statement, and all patients quarantined following the positive results, NBC Miami reported.

“Everyone who tested positive was asymptomatic or had mild symptoms, and we continuously monitored their health,” Royal Caribbean said in a statement to the outlet.

The ship had 6,091 passengers and set sail on Dec. 11. Ninety-five percent of everyone aboard – including guests and crew members – were fully vaccinated.

Royal Caribbean said all crew members are fully vaccinated and the cruise line requires guests over 12 years old to also be fully inoculated.

Unvaccinated children under 12 are required to obtain two negative test results before boarding.