Newcastle's COVID-19 testing rates have dropped more than seven times lower than the peak in August with residents urged to remain vigilant despite the lack of local cases.
Cases with unknown sources in Sydney this week along with increased travel in and out of the Hunter during the school holidays have health authorities on high alert.
Hunter New England health controller Dr David Durrheim said as the holidays come to an end, people experiencing any symptoms should get tested before returning to work or school.
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The plea comes as testing numbers dropped to 1402 in Newcastle last week, down from 10,030 in one August week following the Port Stephens family cluster.
Similarly in Maitland, 2270 tests were conducted in a single week in August, compared to 590 last week.
"We've seen quite a large fall in testing in the Hunter," Dr Durrheim said.
"Some of that is to be expected - winter colds aren't occurring like they were, but we are concerned there may be a level of complacency. We understand why - people are enjoying the fact the Hunter has been COVID free for now a couple of months, which is fantastic.
"People are enjoying the holidays but we do know the virus continues to lurk and we have detected some mystery cases again in Western Sydney. I think any time we get an unknown source COVID case in the community that suggests that the virus is circulating and the community remains at risk.
"We've had lots of people from Sydney visiting the Hunter and Northern NSW over the school holidays so people may have inadvertently come into contact with somebody who has the virus."
Related: Coronavirus: Hunter health officials warn residents to avoid Sydney
Dr Durrheim said COVID-19 would remain a risk until a reliable vaccine is developed.
"We've seen with cases in Western Sydney this virus is not going to relax so we need to be certain that we don't relax too much either."
The health district has also ramped up its sewage surveillance during the holiday period in vacation areas such as Port Stephens and Forster to help determine if the virus is spreading.
