The number of confirmed NSW coronavirus cases on Monday rose to 1918 - an increase of 127 on the previous day.

This is a significantly lower rate of increase than in previous days when NSW authorities were reporting up to 200 new cases per day.

But 228 cases of COVID-19 in NSW do not have a clear source of transmission - the key statistic by which authorities are gauging the success of shutdown measures in halting the virus' spread.

Some 26 NSW coronavirus patients are in intensive care.

"It's pleasing we've seen a stabilisation in case numbers," NSW chief health officer Dr Kerry Chant told reporters on Monday.

"It's important to note they can vary and jump around day to day based on testing numbers.

"While pleased, we do need to be cautious, it's the long-term trend that's going to be important."

Australia is now enforcing new rules limiting gatherings to two people unless you are with immediate family.

Ms Berejiklian said people in their 20s and 30s were the worst offenders when it came to flouting social isolation rules and she implored them not to put the vulnerable at risk.

Unless there was a significant and unexpected spike in COVID-19 cases in the state, the current restrictions would not be revised for a month, she said.

"I just want to assure everybody things are in review constantly - this is based on expert advice," Ms Berejiklian said.

"Health experts have told us they'd like to maintain the restrictions we've put in place for at least the next month and then assess."

NSW Police Commissioner Mick Fuller said police would no longer issue cautions for those flouting self-isolation rules - with $1000 on-the-spot fines to be issued.

Police could also arrest and charge those repeatedly ignoring health orders, with a maximum penalty of six months in prison.

"The power of discretion is such an important one for police - in fact, it's our strongest power. But I'll ask police today to really be out there enforcing this," Mr Fuller told reporters.

"We would much rather work with the community on this."

A Sydney man is already behind bars for allegedly flouting his home self-quarantine twice on Saturday before trying to leave the serviced apartment in which he had been confined.

The number of confirmed NSW cases from the Ruby Princess cruise ship, meanwhile, had jumped to 189 on Monday, with three crew members evacuated from the ship to a Sydney hospital.

Mr Fuller gave approval for those crew members to leave the ship.

Two students and a staff member at a Blacktown school have COVID-19 as does a childcare worker and two children in the same suburb.

The Australian Medical Association says infected patients are putting the lives of medical workers and patients at risk by seeking treatment for other ailments while "hiding" coronavirus symptoms.

"There have been some disturbing incidents of people hiding their symptoms in order to get treatment for other health issues," AMA NSW President Dr Kean-Seng Lim said in a statement.

"Fatalities and high numbers of healthcare-worker infections would further strain the health system's ability to respond to this pandemic."

Dr Lim said NSW health workers had to limit scarce supplies of protective equipment to treat symptomatic cases.

Australian Associated Press