Supplied video obtained Friday, March 20, 2020 of NSW Health Minister Brad Hazzard speaks to reporters in Sydney, imploring passengers from the Ruby Princess cruise which returned to Sydney from NZ to self-isolate. The Princess Cruises-operated ship returned to Sydney on Thursday with 1100 crew and 2700 passengers on board. Doctors tested 13 unwell patients for COVID-19, with three found to have the virus. (AAP Video/Supplied/ABC) NO ARCHIVING AAP VIDEO BEYOND 48 HOUR NEWS USAGE

Ruby Princess passengers told it's not OK to be moving around

Authorities say they have made contact with thousands of passengers from a cruise ship that docked in Sydney after four people tested positive for coronavirus.

About 3800 passengers and crew were on board the Ruby Princess before it arrived in Sydney and the 2647 passengers were allowed to leave.

NSW chief health officer Dr Kerry Chant said all passengers had been contacted by text and email with authorities next making follow-up phone calls but it’s not yet clear how many have actually been reached.

The reality for health authorities is that thousands of passenger, possibly exposed to coronavirus, are now scattered across Sydney.

Dr Chant said the cruise ship company would take care of the 1148 Ruby Princess crew. “They have doctors on board the ship, they have ICU facilities, they have care,” Dr Chant said.

Health Minister Brad Hazzard told reporters on Friday that the ship had completed a relatively short cruise around the Pacific to New Zealand. It left Sydney on March 8 and returned to the city on Thursday morning.

“On board there were some people on board the cruise ship who presented with flu-like symptoms,” Mr Hazzard said.

The doctor on board did 13 swabs to test for coronavirus and three passengers, who disembarked at Circular Quay, were later confirmed to have COVID-19. They are receiving treatment in Sydney.

A fourth case is a crew member who is in isolation and is still on board the ship.

Of the 1148 crew, 98 have left the ship and NSW for their home countries. The rest of the crew remain in isolation on board the ship, which is currently at sea, off the New South Wales coast, somewhere between Sydney and Wollongong.

Mr Hazzard said one of the passengers was particularly unwell.

“One of those passengers was not at all well, and was taken off the ship and has been taken to a hospital here in Sydney, and is being cared for. That particular passenger, now patient, is not particularly well.”

Mr Hazzard said it was very important for those who had left the ship to self-isolate in their homes for 14 days.

Sixty-three per cent of the passengers were Australian residents while 20 per cent were from America and the rest were from a variety of other countries.

“If you start to show any of the symptoms, whether it a fever, a cough, or any of the other well-known symptoms that can associate with - like flu, obviously - we want you to make sure you report that in, and take due medical advice,” Mr Hazzard said.

“It is actually serious, because if we have nearly 2,700 people that were passengers on that ship, we want to know every single one of them is in quarantine.”

He earlier said contacting nearly 2700 people was “a bit of a journey” and some had not responded.

“I'm asking the media to get that message out to the community. And to the community: If you know somebody who came in yesterday from the Ruby Princess, do our community a very big favour and have a chat and make sure that they are given this clear message.

“Put yourself in a self-isolation. Follow the rules, and if you're feeling ill, any of the symptoms that might be related to COVID-19, then make sure you contact a medical practitioner, either your local GP or the local ED in the hospital, and then take advice on what you should be doing.”

The number of COVID-19 cases in NSW has increased by a “substantial” 75 people to reach more than 380.

Mr Hazzard said there had been an extra 75 cases in the 24 hours to 11am taking the total to 382.

“It’s obviously quite a substantial increase and, again, it’s indicative of the growing issue that faces the entire world,” he said.