Five more people have been diagnosed with coronavirus in the Hunter New England Health (HNEH) district.
Four of the five newly confirmed cases on Friday have recently returned from overseas, the health service confirmed.
A woman in her 50s and a man in his 60s are in home isolation after returning from Italy.
A woman in her 20s was diagnosed after coming home from a cruise in the Pacific; and a teenage woman is in isolation after returning from Canada recently.
HNEH said one of the cases also is a man in his 70s who is a relative of a previously reported confirmed case.
It now brings the total number of coronavirus patients in the HNEH area to 18, which is a stark jump from two confirmed cases last weekend.
A spokesperson for HNEH said the patients will self-isolate for 14 days and health staff will check in with them daily and monitor their health.
Despite there being no dedicated coronavirus testing clinics in Tamworth or Gunnedah, a new drive-through COVID-19 clinic has opened at Belmont Hospital.
It is the fourth to open in the HNEH district, joining clinics at John Hunter, Maitland and Calvary Mater Newcastle hospitals.
Chief Medical Officer Brendan Murphy pleaded with Australians not to go out with "a sniffle or a cold".
"This is critical now. We have to slow the curve," he said. "... There is a risk that if we don't do what every one of us has to do as our civic duty to control this spread, it will grow significantly greater."
It was now crucial for people to stay away from each other, he said.
"You should be distancing yourself from every fellow Australian where possible. That's why we have guidelines for people in gatherings of less than 100. It's no point having a gathering of 20 people if it's in a tiny room and you're all together.
"You've got to practise social distancing. Keep that metre-and-a-half away from each other, practise good hand hygiene all the time, and stay away from work or the community if you are unwell. This is also incredibly important," he said.
"Nobody should be going to work or mixing with society or friends, or going out if they are unwell at all."
Professor Murphy also referred to reports of people flouting the 14-day quarantine rules after coming back from overseas.
"This issue of quarantining when you come home is serious. This is not an advisory. This is your civic duty to your fellow Australians to stay home for that entire 14 days, if you've come back to Australia. No exceptions.
"And if you see anyone who is not abiding by that, a recent traveller, make sure they do because we are really serious about that. It has such a big impact on our outbreaks in the last few days."
HNEH Executive Director of Rural and Regional Health Services Susan Heyman said locations of patients weren't being disclosed to the public because of privacy and to not create "fear that's not warranted".
"As a local health district we're giving information about each positive case that comes forward, we're just not explicitly saying what town," she said.
"We've got a lot of very small towns and people could be identified and that's not very respectful, and it could also create a lot of fear that's not warranted."
- with Kirsten Lawson and Jessica Worboys
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