NSW Health's Jeremy McAnulty says there are now 116 cases in western NSW, with 16 new cases in Dubbo and two in Bourke.

The first person diagnosed in Broken Hill has been infectious since Friday and had been mingling there and in Wilcannia until being diagnosed on Monday.

It is not yet known how transmission occurred and identified contacts are being tested.

Premier Gladys Berejiklian says western NSW "remains of enormous concern around west Dubbo, Walgett and also in Bourke".

Of the 452 new cases in the state in the 24-hours until 8pm on Monday, 10 are from Hunter New England (five in Maitland, two in Newcastle, three in Lake Macquarie), one is from the Central Coast, one is from Illawarra Shoalhaven and seven cases are yet to be assigned.

There are now 130 cases in the Hunter New England district.

Deputy Premier John Barilaro said resources were being focused on vaccinating "the vulnerable community in western NSW".

"Don't get caught up in the AstraZeneca versus Pfizer debate," he said.

"I don't want to see a future where regional communities are behind the target set by the government because of a lacklustre approach to getting vaccinated."

There are now 107 confirmed cases of the virus in Dubbo, two in Bourke, three in Mudgee and four in Walgett, and Dr McNulty says most of the cases are in the Indigenous community.

"So we're working closely with the Aboriginal community to keep them safe, to make sure that people are getting tested and making sure that people who have been in contact with other cases are aware that they need to isolate," he said.

"And special accommodation is being set up for people to make sure they're kept safe."

NSW Health was investigating whether a funeral in southwest Sydney led to any cases in Wilcannia, in the state's northwest.

Twenty-five ADF personnel are due to arrive in Dubbo on Tuesday to help administer vaccines, assist COVID testing clinics and enforce stay-at-home health orders.

Two schools in Dubbo remain closed while staff and students have been asked to get tested for the virus and isolate for a fortnight while non-urgent elective surgery has been postponed in the region.

Meanwhile, NSW Health's ongoing sewage surveillance program has detected fragments of the virus at the Lennox Head sewage treatment plant that services about 7700 people on the north coast.

Dr McNulty said the detection was of particular concern, as there were no recent known cases of COVID-19 in the area.

"Everyone in this area is urged to monitor for the onset of symptoms, and if they appear, to immediately be tested and isolate until a negative result is received."

Australian Associated Press