(CBS Newspath) — 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. 

The Celebrity Millennium ship set sail last week with a “fully vaccinated” crew and adult guests, according to the company.  All guests on the cruise were required to show proof of vaccination and a negative COVID-19 test within 72 hours before sailing from St. Maarten last Saturday. Crew and guests also had to follow “comprehensive protocols” that align with destination partners. 

Royal Caribbean has not held cruises since March 2020. The Celebrity Millennium had 648 passengers and over 95% of them were fully vaccinated, CBS Miami reported. Children who could not yet receive vaccinations were required to show negative COVID-19 tests. 

The positive tests come as Republican governors in Florida and Texas are refusing to let companies require passengers to prove they’ve been inoculated, despite the CDC recommendation that 95% of all passengers have to be vaccinated when sailing from U.S. ports. The cruise industry spent over a year negotiating with the CDC on how to safely protect against COVID and prevent super-spreader events.