It was meant to be the trip that showed American cruise fans it was safe to get back on the water, with fully vaccinated crew and passengers no longer needing to wear masks or keep six feet apart. But the owners of the Celebrity Millennium cruise ship confirmed that two passengers have tested positive for COVID-19. The two, who had been sharing a stateroom on the Caribbean voyage, are now in isolation but have shown no symptoms of the virus since Thursday’s tests.

The seven-day cruise left St Maarten on Monday, with stops planned for Barbados, Aruba, and Curacao. All crew are fully vaccinated and reports suggested that 95 percent of the 500-odd passengers are also double-jabbed. American “cruise expert” Stewart Chiron, who is on the ship, told NBC Miami that seven other passengers who had contact with the pair had been confined to cabin pending PCR test results. “It's been normal,” he said. “You would think, well, if people were concerned, you'd see fewer people at dinner around the ship, but the show is ongoing... No one is wearing masks, so it appears that no one is too concerned.”