The 712 new cases make up almost a third of the 2566 new cases recorded across the state in the same reporting period. There were 148,937 tests completed statewide in the period.

Hunter New England Population Health public health physician Dr David Durrheim urged the community to get tested if they experience even the mildest symptoms.

"We urge anyone who is yet to receive their vaccination to do so and book in for a booster if eligible," he said.

"We also strongly encourage the community to continue to wear masks, particularly in indoor environments and avoid crowded venues and indoor gatherings."

Of the Hunter New England's 712 new cases, 356 are from Newcastle local government area (LGA), 176 are from Lake Macquarie LGA, 85 are from Maitland LGA, 35 are from Port Stephens LGA, 19 are from Cessnock LGA, 10 are from Singleton LGA, seven are from Muswellbrook LGA, six are from Mid Coast LGA, six are from Tamworth Regional LGA, four are from Moree Plains LGA, three are from Upper Hunter LGA and two are from Gunnedah LGA.

Armidale LGA, Glen Innes Severn LGA and Narrabri LGA each have one case.

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There are currently 3725 active cases in the district. Of these, 17 are being cared for in hospital, including three in intensive care.

Premier Dominic Perrottet appeared before the media with Health Minister Brad Hazzard and NSW Health deputy secretary Susan Pearce on Sunday, to encourage NSW residents to have their booster shots as soon as they are eligible.

Mr Perrottet was asked whether the state government was doing enough to stem rising case numbers.

"I think we've always struck the right balance here in NSW and generally around the country when it comes to the handling of the pandemic," he said. He said NSW had the highest vaccination rate in the country and one of the highest in the world "and that enables us to be able to learn to live alongside the virus".

He said the government was "monitoring the situation" and the low number of ICU presentations was "incredibly positive". He said most of these patients were unvaccinated.

"It's a time for calm, but it's also an important time to go out and get your booster shot because vaccination has been key to NSW's success."

Mr Perrottet was asked what the threshold would be for reintroducing restrictions.

"We'll look at that, what's key to us as well is personal responsibility, we have mandated masks in high risk settings, we strongly encourage the use of that, everybody today I think is responding incredibly well," he said. "We monitor the situation, ICU presentations are the key metric for us.

"We want to make sure that our health system has the capacity as we move through this next challenge of the pandemic and I'm incredibly confident, as Premier, that our health system is the strongest in the country, that we can deal with the challenges that come our way."

Mr Perrottet was asked whether he expected any restrictions to be imposed before Christmas.

"Every day we're monitoring the situation, every day we look at the numbers in front of us, hospitalisations and the ICU presentations and we will continue to take a balanced, proportionate and measured response... but this is all about taking personal responsibility and the people of NSW are doing just that. The government can't do everything."

Mr Perrottet was asked what the downside was to mandating the wearing of masks indoors, at least until there was more information about the impact of Omicron.

"We strongly encourage it, there will always be different opinions from time to time, I accept that, we have regular discussions, we are always assessing the situation," he said. "I have said as Premier we will tailor our response as the situation evolves and we will always do that. That's exactly what we've done over the last two years, when we believe there is evidence in front of us that we need to potentially tighten restrictions, we will."

He said there would be unexpected curveballs and likely new variants that emerge.

He said cases would continue to increase.

Mr Hazzard said NSW Health facilities alone had given 57,000 booster shots in the week to Saturday, up from 15,000 in the preceding week.

Ms Pearce said she would like to see the number of booster shots double within the next week.

Mr Hazzard said by the end of January, 40 per cent of all vaccinated people would be eligible for a booster and this would climb to 91 per cent by the end of April.

He said he would like to see the recommended time between second dose of vaccine and the booster shot shortened from five months to four, or even three.

"I think I've made it very clear that my view, based on the public health advice I respect, is that it would be helpful to have a shorter period than is currently being designated by ATAGI," he said.

"At the moment they're sitting on the five months and I think there are very strong arguments to say that it should come to a shorter period, and if it's not three months then possibly four months."

Mr Hazzard said this would put pressure on the state's public health team, "but that's a challenge I'd like to see us at least face up to".

He said NSW Health would in a limited number of circumstances offer boosters in its clinics from 4.5 months after the second dose of vaccine.

Ms Pearce was asked when Omicron would be the dominant strain.

She said the "big missing piece for us" was the severity of illness with Omicron.

"Those are the signals that we're looking for, everybody across the world is earnestly waiting and watching the severity, so that will be key to us.

"With respect for example to the cases that we're seeing at the moment, our eyes are really on that factor.

"The number is one the thing but the severity will be the thing that makes the difference and that is still at this stage unknown."

Ms Pearce said Australia was in a "somewhat different position" to the Northern Hemisphere, which is facing Omicron in its winter months.

Mr Hazzard said his comments from last week about a possible 25,000 new cases a day in January came with qualifications.

"Modelling is only as good as the inputs you have and and when you don't have a very high case load directly relevant to Omicron - and we don't at this point have huge numbers and of course there's the lag period as well, we don't know what will happen after a week or two of people becoming infected," he said.

"That modelling was put together by UNSW and it seems to be excellent modelling but it also is modelling that has qualifications around it.

"It adds to our sense of heightened alertness but it's not definitive, it's not locked in..."

NSW Health said of the 2566 new cases across the state, 313 have been confirmed as the Omicron variant of concern. It advised the Omicron variant of concern likely accounts for the majority of the 2566 cases.

"With the high number of COVID-19 cases now in NSW, NSW Health will only undertake genomic sequencing for the Omicron variant in the circumstances where it will make a clinical difference to the care of a patient," it said. "For instance, where it will inform treatment choices as some therapies work with Delta but not for Omicron, and in situations where it will inform public health action."

Those eligible for a booster dose can book in at a NSW Health vaccination clinic through the COVID-19 Vaccine Clinic Finder. They can also book a booster dose at a participating pharmacy or GP.

Operating hours for the Hunter's COVID-19 testing clinics are here.

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