The new Omicron variant of the coronavirus is possibly even more transmissible than the Delta strain that sent NSW into a months-long lockdown, says the state's health minister.

While cases of the new variant have not yet been identified in NSW, Health Minister Brad Hazzard has warned residents to be on high alert.

"One of the problems with this highly contagious virus, in any of the variants, is that it tends to be out hidden in the community and then announces its presence when we least expect it," he said on Saturday.

The strain appears to be "dominating Delta", he said, which is "concerning for anybody in public health".

People in NSW who have been in southern Africa - including South Africa, Lesotho, Botswana, Zimbabwe, Mozambique, Namibia and Eswatini - in the last 14 days are being urged to get tested, contact NSW Health and self-isolate until they get further instructions.

Anyone sharing a household with arrivals from those countries should also isolate until further notice.

Travellers who fail to notify authorities that they have been in southern Africa are likely to be contacted by text message and reminded of their testing requirements.

Mr Hazzard said people should consider wearing masks even where the rules do not currently require it, especially when they are near large groups.

Premier Dominic Perrottet said there would be no immediate changes to NSW's reopening roadmap.

"We have committed to the roadmap, we will always look at issues as they arise," Mr Perrottet said.

The premier warned against complacency, reiterating the pandemic is far from over.

"We will always strive to keep the community safe whilst balancing that with keeping the economy open and keeping people in work," he said.

Mr Perrottet discussed the new variant with Prime Minister Scott Morrison on Saturday morning.

NSW will work with the Commonwealth to implement changes the federal government will introduce to tackle the Omicron threat.

Health experts around the world are working to understand the new variant, which has a higher number of spike protein surfaces.

In particular, Mr Hazzard said, it is not yet known if the COVID-19 vaccines are any less effective against the strain.

Meanwhile, the state added 235 new infections to its COVID-19 caseload on Saturday, and no further deaths.

NSW's hospitals continue to treat 174 coronavirus patients, 26 of them in intensive care units and 10 requiring ventilation

Health officials say testers processed more than 62,000 results in the 24 hours to 8pm on Friday.

NSW is now 94.5 per cent single-dose immunised for everyone aged 16 or over, while 92.3 per cent of the same group are fully vaccinated.

Of 12-15-year-olds, 81.2 per cent have received one jab and 76.2 per cent both.

Should NSW reach its goal of 95 per cent full coverage by December 15 an early easing of restrictions will trigger, according to the state's roadmap out of lockdown.