UPDATED: A Royal Caribbean “cruise to nowhere” was cut short and the ship returned to Singapore on Wednesday after an elderly passenger was diagnosed with the coronavirus, but the health ministry later said new tests on the man were negative.

The 83-year-old passenger on the Quantum of the Seas tested positive for COVID-19 after reporting to the ship’s medical centre with diarrhea and was immediately isolated, Royal Caribbean and Singapore’s Tourism Board said.

But Singapore’s health ministry said later Wednesday that it retested the man’s original sample as well as a new sample and found them negative. It said it will conduct another test Thursday to confirm his status.

Singapore recently began a “safe cruising” pilot program allowing cruise ships to make round trips from Singapore with no port of call in between. Strict safety measures were imposed, including reducing capacity by half and pre-board testing of passengers. Royal Caribbean is one of two operators licensed to run such trips.

Annie Chang, director of cruise at Singapore’s Tourism Board, earlier said the man had tested negative prior to boarding. She said his close contacts were isolated and tested negative.

Chang said all leisure activities on board the Quantum of the Seas had ceased immediately and passengers and crew were asked to stay in their cabins until contact tracing was completed. She said all people onboard would undergo mandatory COVID-19 testing before leaving the terminal.

“They are being given regular updates and meals are provided directly to their rooms,” Chang said. “The well-being and safety of our local community, as well as passengers and crew remain a top priority.”

The Singapore Straits Times reported that the vessel, which had 1,680 guests and 1,148 crew members on board, returned on the third day of a four-day trip.

Royal Caribbean said in a statement that it had worked with the Singapore government to develop a thorough testing and monitoring system.

“That we were able to quickly identify this single case and take immediate action is a sign that the system is working as it was designed to do,” it added.

Singapore, a small but wealthy city-state in Southeast Asia, has reported 58,291 coronavirus cases including 29 deaths.