It brings the coronavirus cluster in the Armidale local government area to three, following Saturday's revelation two people had contracted COVID-19.

The teenage girl is a household contact of the other two, while a fourth person in the home is yet to return a positive case.

Armidale and Guyra entered a snap lockdown at 5pm on Saturday, which is schedule to last until 12.01am on Sunday August 15.

Member for Northern Tablelands Adam Marshall said he was not surprised to see a third case given how highly transmittable the delta strain is.

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"I'm always hoping that we see no extra castes, but given what we know about household transmission and the delta variant the third case of infection of another person is that one household is (not) unexpected," he said.

"There is another person in that household that hasn't tested positive yet so it would not be surprising if there was to be a fourth case from that one household revealed in the next 24 hours or more."

Given the cases are currently restricted to the one house, Mr Marshall was confident the LGA can exit lockdown on time and avoid it spreading further.

"I'm very hopeful and I'm as confident as I can be, we're not the first community to go through this, we saw a recent example at Orange where they got through it," he said.

"And I must say the community has been absolutely wonderful, everyone has been doing the right thing, there's been thousands of people go and get tested.

"I can't praise the community enough for the way it has responded both accepting the lockdown, complying with the lockdown, getting tested and looking out for each other."

A 'low-level detection' positive COVID-19 case was also reported for a male in his 40s at Boggabri Coal on Saturday evening, plunging the mine site into an immediate shutdown.

NSW recorded 262 new COVID cases from 95,000 tests in the 24 hours to 8pm last night, Premier Gladys Berejiklian said this morning at her daily coronavirus press conference.

There were another six overseas acquired cases.

Ms Berejiklian said 50 of the 262 cases were active in the community.

A woman in her 80s, who was not vaccinated, was the sole fatality yesterday.

Ms Berejiklian said the Canterbury-Bankstown area was still the epicentre of the NSW outbreak.

Deputy police commissioner Gary Worboys said Western Sydney was also the centre of police attention, with 171 of 454 infringement notices from south-western and north-western Sydney.

Ms Berejiklian said "more positively", the Georges River area was close to being taken out of the list of suburbs described as "areas of concern", and she urged as many people as possible to come forward for testing to give the experts "the confidence" to remove the listing.

She said another four Sydney suburbs had been added to the existing eight Local Government Areas listed as areas of concern.

The conference heard there were 362 people in NSW hospitals, including 58 in intensive care, of whom 54 were unvaccinated.

The NSW update followed news from Queensland, where Cairns goes into lockdown from 4pm today, with the south-east Queensland lockdown ending at the same time, but with some restrictions remaining in place.

Also yesterday morning, Federal Minister Greg Hunt said the Therapeutic Goods Administration was about a fortnight away from approving a third vaccine for Australia - the Moderna mRNA inoculation developed in the USA.

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