A Royal Caribbean cruise set sail with all adults fully vaccinated. Then two passengers tested positive for COVID-19 anyway.

Two passengers onboard the Celebrity Millennium cruise have tested positive for COVID-19, cruise operator Royal Caribbean Group announced Thursday. It was the first cruise ship to set sail in the Caribbean in over a year since the pandemic began. 

The Miami-based cruise company said in a statement that both guests, who were sharing a room on the ship, tested positive while it conducted the required end-of-cruise testing. Both passengers are asymptomatic and currently in isolation. "We are conducting contact tracing, expediting testing for all close contacts and closely monitoring the situation," the company said.