NSW could move to lockdown, premier says

But the premier says she's ready to move ahead of the Commonwealth if required and declare a lockdown across NSW over the weekend, while police have been granted powers to crack down on those flouting public health orders.

The number of NSW coronavirus cases jumped on Thursday to 1219, a rise of 190 on the previous day.

Some 16 patients are in intensive care, with 10 requiring ventilators.

Two more children in NSW on Thursday - girls aged one and two - were confirmed to have COVID-19, taking the number of child cases to four.

A midwife at St George Hospital also tested positive for the virus, with her patients contacted and told to self-isolate.

Premier Gladys Berejiklian said on Thursday police would ramp up their public presence and that no cruise ship passengers would be permitted to disembark in NSW until further notice.

She said protocols on disembarkation needed tightening and that she was working with the Australian Border Force on new measures.

The Ruby Princess cruise ship - which disembarked passengers last week without adequate checks - is responsible for 121 COVID-19 cases in NSW.

Ms Berejiklian said the government was "looking very closely" at the impact of Monday's shutdowns on pubs, cinemas and churches - and if they weren't sufficient, further action would be taken.

The main criterion by which success would be judged was community-to-community COVID-19 transmissions, rather than total case numbers.

"I'm saying to the community that if we're not convinced we've had a sufficient amount of success, NSW will have to take further action and that's a position I've been clear on from day one," Ms Berejiklian said.

But chief health officer Dr Kerry Chant said the full effect of the second stage of shutdowns - in place from Thursday - wouldn't be known for some days.

This includes museums, libraries, auctions, beauty services and pools, as well as stronger restrictions on wedding and funeral numbers.

"It does take us at least seven and possibly 14 days to really get a picture ... remember we also have to take out the fact we have returning travellers come in with disease," Dr Chant said on Thursday.

Officers will have the power to issue fines of $1000 to individuals and $5000 to businesses that breach public health orders.

People in the firing line include returned travellers who contravene the requirement to self-quarantine for 14 days and those diagnosed with COVID-19 who similarly don't follow the rules.

Ms Berejiklian, meanwhile, confirmed 292 Australians who had disembarked from the Norwegian Jewel cruise ship in the United States and flown home, were in isolation in a Sydney CBD hotel.

They had been escorted to the hotel by border authorities upon arrival, while five passengers with respiratory symptoms were taken to hospital.

Footage taken at international arrivals at Sydney Airport on Thursday morning and posted to Twitter shows large queues of people lining up very close to one another.

It's understood all passengers arriving at Sydney Airport are undergoing temperature checks, facilitated by biosecurity staff and NSW Health employees but the testing space is too small, a Community and Public Sector Union spokeswoman told AAP on Thursday.

The Department of Home Affairs says Australian Border Force is overseeing social distancing at the airport.

"The ABF continues to encourage all passengers to adhere to social distancing guidelines while disembarking and clearing customs and immigration," a spokesman said in a statement.

A Sydney Airport spokeswoman said every single passenger is spoken to about their obligations.

There are signs about social distancing all over the airport, and on its social media channels, as well as security staff reminding people to comply, a spokeswoman said.

NSW National Parks and Wildlife Service said in a statement on Thursday all campgrounds, high visitation areas and historic sites would be closed until further notice.

Seven people in NSW have died of COVID-19.

Australian Associated Press