PUBLIC health officials believe active cases of COVID-19 could be in Armidale as higher levels of fragments have been detected in sewage.
NSW Chief Health Officer Dr Kerry Chant said while there has been a low detection previously, believed to be related to a case in the area, it's no time for complacency.
"The levels in sewage have become higher and we are concerned there may be active cases in Armidale," she said.
"Obviously we are very concerned about regional NSW and that's why we have protections in place for regional NSW in terms of mask-wearing.
"I know that there's probably been lots of reports and police have responded lots of times to communities highlighting where people are in breach.
"We are very concerned and that's why no-one can be complacent."
Just this week 40,000 doses of the Pfizer vaccination were sent from regional areas to Sydney for HSC students, though the federal government will resupply regional areas on August 16.
It comes as Premier Gladys Berejiklian announced the Hunter will lock down for a week.
All Hunter LGAs including Dungog will fall under the harsher restrictions as seen in Greater Sydney from 5pm on Thursday.
It follows cases at schools in Maitland and Lake Macquarie, as well as an exposure at University of Newcastle's Auchmuty library.
Ms Berejiklian said testing overnight had revealed there were "some cases" in the Hunter but did not immediately specify how many had been detected.
NSW has recorded 262 cases in the past 24 hours.
45 were infectious in the community, while five people have died in the same period; three in their 60s, one in their 70s, and one in 80s.
Dr Kerry Chant said five people were being cared for in the Hunter and investigations were underway, but they believed the source of infection was a Lake Macquarie gathering.
"We now think that the source extended from a gathering on Blacksmiths beach on Friday night," Dr Chant said.
Dr Chant confirmed two Maitland Christian School students were among those infected.
"All of the parents and children are asked to go home and isolate and we will provide further information," she said.
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