Public health controller Dr David Durrheim said in a statement that the Hunter outbreak "originated from a young adult" who arrived on Tuesday, July 27, and spread the virus at a host of locations until leaving five days later.

"This person stayed in the Hunter between 28 July and 1 August, attended multiple venues across the region, including licensed venues, shopping centres, a party in Shortland and the Blacksmiths beach gathering," he said.

"The Shortland party and Blacksmiths beach gathering are confirmed transmission events."

He said contact tracers had not established a link to positive cases at the University of Newcastle but, based on the movements of infected people and their onset of illness, transmission likely occurred at a licensed venue in Newcastle.

HNEH added the Cambridge Hotel, Great Northern Hotel and Babylon bar to its list of exposure sites on Tuesday.

The Blacksmiths gathering on July 30 was initially identified as the source of the Hunter outbreak until exposure sites emerged from two days earlier.

"We plead with the community that if you are identified as a confirmed case or contact to please provide us with all the information our contact tracers require to quickly inform our community that a venue may be an exposure site," Dr Durrheim said.

On Tuesday, Dr Durrheim said it was "extremely disappointing" to learn that partygoers at the Blacksmiths and Shortland sites had been out in the Newcastle community longer and earlier than first thought.

More COVID news

Police said on Wednesday that they were investigating the Shortland gathering "as part of an overall investigation into potential breaches of the public health order in the Newcastle City and Lake Macquarie police districts".

NSW chief health officer Dr Kerry Chant told an upper house inquiry on Tuesday that a "handful" of people were "absolutely doing the wrong thing" when they seeded "two COVID-19 clusters" in the Newcastle community.

"Clearly our concerns have escalated since the impact in Newcastle, and that's been linked back to a handful of people doing the wrong thing," she said.

"They seeded two separate clusters in Newcastle."

She said some people had "wantonly disregarded" stay-at-home orders, without referring specifically to the Newcastle outbreak.

The exposure times for the Cambridge, Great Northern and Babylon stretch from 7pm on July 30 to 3am the following morning.

Three days later, health authorities found a "very high viral load" in sewage at the Shortland and Burwood waste water plants, as well as a smaller detection at Belmont.

The list of Newcastle exposure sites stretches back to the morning of Wednesday, July 28, at the university's International House, a residential complex for students.

The exposure sites also include Shortland Hotel and Shortland 7-Eleven on that day.

Shortland Hotel and Big W at Jesmond were exposure sites on July 29, the former from 9pm to midnight.

Several shops at Charlestown Square also became exposure sites that day.

Premier Gladys Berejiklian said on Wednesday that it was unlikely the Hunter would emerge from lockdown on Thursday due to a growing number of COVID cases in the region.

A 52-year-old man from Rose Bay in Sydney has been issued with a court attendance notice after allegedly breaching public health orders and sparking a lockdown in the Byron Bay area.

Zoran Radovanovic, who is being treated in a Lismore hospital, potentially used a loophole in COVID-19 rules to travel to the area to look at real estate.

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