A team of 30 detectives from state crime, counter terrorism and marine area command are investigating the communications and actions which led to the docking and disembarking of the cruise ship in Sydney Harbour on March 19.

The first briefing into the investigation was held on Wednesday morning, NSW Police said.

High-priority witnesses will be interviewed in the coming days with police urging anyone with relevant information to contact Crime Stoppers.

Meanwhile, new COVID-19 infections continue to stabilise with NSW recording 48 new cases on Wednesday, taking the state's total to 2734.

There are 36 people in intensive care and the death toll remains at 21.

NSW Premier Gladys Berejiklian on Wednesday welcomed the ongoing stabilisation and decline of new cases but warned community transmission was still increasing.

She said that while social distancing would be necessary until a coronavirus vaccine or cure is found, restrictions are being reviewed on a month-by-month basis.

"If the advice in a couple of weeks' time is that there might be a couple of aspects that we can tweak to provide relief to our citizens, well then we'll take that advice," Ms Berejiklian told reporters.

"But that comes with risk and I need to be very up-front about that.

"Every time you relax a restriction, more people will get sick, more people will die, and it's a horrible situation to be in but they're the choices."

The premier said the government was getting advice on what schools would look like in term two, and what business activity could look like.

She reminded people to adhere to restrictions, which are having a positive effect, as authorities keep a watchful eye on increasing community transmission.

Police are continuing to enforce self-isolation regulations, with 136 fines and 11 court attendance notices issued across the state since March 17.

NSW Health says there are 36 travellers currently in hotel quarantine who have tested positive to COVID-19, and 121 quarantined travellers showing coronavirus symptoms.

NSW Chief Health Officer Kerry Chant said one adult and one child in a family group of seven had been confirmed to have COVID-19, after children were photographed being transported for testing on Tuesday night.

They had been staying at the Hilton hotel in Sydney, where a number of people are in quarantine after returning to Australia.

The first group of 288 Australians quarantined at the nearby Swissotel were released on Wednesday morning, under a police operation to ensure their departure is quick and seamless.

This group arrived in Australia on March 26 and have undertaken a mandatory 14-day self-isolation, to protect the community from the coronavirus.

Gold Coast woman Christine Cooper told AAP she and her husband were well looked after during the "long two weeks".

"It's weirder getting out," Ms Cooper said on Wednesday.

"You feel like an inmate that's been in jail and now you've been released."

All received a letter confirming their period of isolation and underwent a final health check.

After Wednesday's operation, police will plan for further departures when some 3000 Australian residents are expected to leave hotel isolation over the next week.

Meanwhile, the Ruby Princess remains docked in Port Kembla, near Wollongong, where it's expected to remain for 10 days while 1040 crew members undergo medical assessments.

About 200 crew have shown symptoms of coronavirus, while 18 crew have so far tested positive.

Australian Associated Press