With 1204 people now hospitalised with the virus - up from 1066 the day before - and more than 2500 health workers furloughed, the health system is under strain.
"We are seeing health systems around the world put under stress and whilst we are very well placed ... it is important that we all play our part in not placing unnecessary burden on the health system," said Chief Health Officer Kerry Chant on Monday.
People should avoid going to the emergency department to seek PCR tests for COVID-19 if they're not unwell, Dr Chant said.
"That potentially compromises the care of those that need it," she said.
"I know that people want to know what their diagnosis is and want to get that test result but can you also just think about some of the implications of those actions."
Dr Chant reassured NSW residents that the health system is still there for those who need it, urging people with health concerns not to delay seeking treatment.
As of December 30, 2510 healthcare workers were in isolation after being exposed to COVID-19.
Intensive care numbers jumped by 12 to 95 overnight. Twenty-five people are being ventilated.
Not all those in hospital with coronavirus were admitted for treatment for COVID-19, according to new data.
NSW Health says that a small sampling of hospital patients with COVID-19 in two local health districts over the past two weeks shows that some were admitted for unrelated illness or injury.
They include women giving birth, people seeking mental health care, and people with appendicitis or bowel obstruction, a NSW Health spokesperson said in a statement.
The agency did not respond to questions about whether a similar proportion of hospitalisations during the Delta wave was primarily for other reasons.
The spokesperson said it's to be expected as case numbers in the community rise, that some patients will present with other conditions as their primary reason for seeking health care.
Dr Chant also urged parents to get their children vaccinated before school returns in four weeks.
The vaccination rate for 12- to 15-year-olds has been "stubborn", lingering around 80 per cent, she said.
"We would like to see children fully vaccinated to commence the school year and because of the interval you need to act now so they can get the two doses in before commencing school," she said.
The new cases were diagnosed from 96,765 tests processed in the 24 hours to 8pm on Sunday.
More than one in five people - 21.5 per cent - getting PCR tests are receiving positive results.
The four deaths included two people in their 70s and one each in their 80s and 90s. Three had received two doses of the vaccine and one had received their booster.
Cases are surging in western Sydney, which saw 4047 new cases, closely followed by south western Sydney with 3966 cases.
The Hunter New England local health district continues to see high case numbers, with 1612 more people diagnosed in the latest reporting period.
Twelve new cases were diagnosed in the state's jails.
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