NSW could see 25,000 COVID-19 cases a day by the end of next month, Health Minister Brad Hazzard has warned, after a dramatic escalation in the number of new infections.

Some 1360 new cases were detected in the 24 hours to 8pm on Tuesday, an increase of 556 on the 804 the previous day.

Infections have more than quadrupled in a week and it is the first time in months the state has recorded more than one thousand new cases in a single day.

Health authorities believe the Omicron variant is causing the rapid surge in cases.

While only 110 cases have been officially confirmed, due to testing limitations, data indicates Omicron cases are rising in Sydney and the variant has "predominance" in Newcastle.

The Hunter region remains the biggest headache for authorities, with the district accounting for about one-third of new cases on Tuesday thanks to super-spreader events in Newcastle.

Mr Hazzard said cases in NSW are bound to surge further, with experts warning the "concerning" reproduction rate of the variant could climb above 1.5.

"What they're telling us is that by the end of January, we could be looking at 25,000 cases of the virus every single day," he said on Wednesday.

"That takes us, on my maths, to about 175,000 in a week."

While it seems the new variant is more transmissible but causes less severe illness, Mr Hazzard said those number should compel people to get their vaccine boosters as soon as they are eligible.

Many are heeding that message, with 9000 booster doses handed out across the state on Tuesday.

Researchers from UNSW's Kirby Institute on Wednesday also stressed the importance of booster shots.

While two doses of any vaccines had little to no effect on the transmissibility of the Omicron variant, protections against severe disease - particularly with a booster shot - remained.

"Having a booster shot with an mRNA vaccine... (offers) around 85 per cent protection against symptomatic disease and around 98 per cent protection against severe disease," Dr Deborah Cromer said.

The explosion across NSW in cases coincides with an easing of restrictions, with unvaccinated people now allowed to mingle with the fully jabbed at shops and hospitality venues for the first time in three months.

QR code check-ins have also been scaled back and masks are only required in high-risk settings such as public transport and planes.

There are no limits on visitors to homes, hospitality venues, or outdoor gatherings.

But while masks are no longer required, Chief Health Officer Kerry Chant says her "clear advice" is for people in indoor settings to keep wearing them.

Premier Dominic Perrottet defended the decision to ease restrictions as planned, and urged people not to focus on rising case numbers but rather ICU presentations and hospitalisations.

The last time NSW had a higher daily infection caseload was on September 11, when 1599 new cases were detected.

But the number of hospitalisations and deaths in NSW are a fraction of what they were then.

There was one death on Tuesday, while 166 people are in hospital with the virus, including 24 in intensive care and seven ventilated.

While hospitalisations generally lag infection spikes, Mr Perrottet has "complete confidence" the hospital system will cope thanks to the state's 93 per cent vaccination coverage.

Restrictions will be changed only if needed.

"It's for me to look at the evidence that comes before us not to pre-empt what may or may not happen," he said.

He rejected suggestions his government was sending confusing messages by warning cases could climb and urging caution, while at the same time easing restrictions and encouraging people to "enjoy the best that NSW has to offer".

"It is all about instilling confidence and ensuring everyone has a safe Christmas," he said.