Four of the other newly confirmed cases of COVID-19 are close contacts of people who attended a Sydney Church of Christ service at Ryde Civic Centre on March 8. Health authorities are urging the 300 other attendees to monitor for symptoms for the next two days, as their chance of having COVID-19 is "slightly increased". Trevor Spencer, 75 with his wife Julie after disembarking from the Ruby Princess on Thursday. Credit:Kate Geraghty Two staff members at Sydney's high-security mental health Forensic Hospital at Malabar are also among the new cases, forcing dozens of staff at the facility into isolation. The ship's on-board doctor swabbed 13 people who showed signs of cold and flu symptoms and the four positive results were confirmed on Friday. The ship was considered low risk because it came from New Zealand, NSW Health said. The infections only became public 24 hours after the ship docked. One of the confirmed cases is a crew member from the Ruby Princess who was allowed to re-board the ship, which is now at sea between Sydney and Wollongong.

NSW Health Minister Brad Hazzard urged all 2647 passengers and 1148 crew to self-isolate immediately and contact health authorities if they develop symptoms. Sixty-three per cent of those on-board were Australian residents, 20 per cent from the US, with the rest coming from a variety of other countries. Loading Mr Hazzard said it was possible other passengers in Sydney had unknowingly contracted coronavirus. "Our big concern, the very big concern, is that those people came off the cruise with no knowledge of COVID actually being on their ship," he said.

"If they think that it's not necessary to do the 14 days, and if they think that it's OK to be wandering around, the clear message from me ... is, no, it's not. "It is actually serious because if we had 2700 passengers on that ship we want to know that every single one of them is in quarantine.” Passenger Trevor Spencer said he and his wife Julie were "surprised" they were not asked questions about their health or subjected to temperature tests before they disembarked from the ship. "We were of the opinion that they were going to check us as we disembarked. But they didn't. We just walked straight off," Mr Spencer said. "We're feeling pretty comfortable. It is what it is. The chances are we might get it."

The couple waited in Circular Quay for about an hour before a pre-booked driver collected them and took them home to an over 55s retirement village near Penrith. Two passengers aged in their 70s are being treated in the dedicated COVID-19 intensive care unit at Royal Prince Alfred Hospital. One patient is severely unwell. A third, from Tasmania has also been diagnosed and is being assessed in a Sydney hospital, and a fourth, also in Tasmania, is awaiting test results. Chief Health Officer Kerry Chant said all passengers had been sent emails and text messages alerting them to the situation, directing them to self-isolate. Some passengers have not responded.

Dr Chant said NSW Health had been in contact with the cruise line, which was managing the situation. "They have doctors on-board the ship, they have ICU facilities ... now with all the passengers off the ship they have the ability to reallocate all the crew to single rooms with bathrooms," Dr Chant said. The Princess cruise line also operates the Diamond Princess vessel on which almost 700 people contracted coronavirus when it was quarantined in Japan for two weeks in February. Loading Replay Replay video Play video Play video In a statement a spokesperson for Princess Cruises said all passengers with flu-like symptoms, as well as their cabin occupants, were in isolation aboard the ship to minimise their contact with guests.