New exposure sites in Huskisson, Jervis Bay, Goulburn and Gundagai

NSW Health has also identified several new close and casual contact exposure sites in Huskisson, Jervis Bay, Goulburn and Gundagai from May 19 to 24.

It came after a Melbourne man tested positive for COVID-19 on Tuesday, after holidaying with his family in NSW last month.

"The original timeframe has been expanded, as three household contacts of the original case have now tested positive," NSW Health said in a statement.

A list of exposure sites in Hyams Beach, Jervis Bay, Vincentia and Goulburn was released on Tuesday night. That list has grown, with the addition of several exposure sites in Huskisson and Gundagai.

"NSW Health is continuing to investigate the movements of these cases in southern NSW, and this list of venues may be updated," NSW Health said.

"Anyone who lives in Jervis Bay, Vincentia, Huskisson, Gundagai or Goulburn, or has visited these areas since May 19, is asked to be especially vigilant for the onset of even the mildest cold-like symptoms, and is urged to come forward for testing immediately if they appear, then isolate until a negative result is received."

A pop-up testing clinic will be open at the Gundagai Visitor Information Centre from Thursday, operating from 10am to 4.30pm.

"NSW Health has already increased testing capacity on the South Coast with a new pop up drive-through in Huskisson, and extended hours at existing clinics."

Victorian authorities believe the strain circulating in the state is much more infectious than previous variants, capable of transmitting between strangers with very minimal contact.

Those concerns prompted the Victorian government to extend the lockdown for Greater Melbourne for at least another seven days until midnight on June 10.

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NSW chief health officer Dr Kerry Chant said she was working with Victorian health authorities to determine whether the man was the source of the transmission to his family members, or vice versa.

"If this gentleman was the source for those individuals, they were not infectious potentially when they were in NSW," she said in the press conference earlier today.

"If the reverse is the case, that may take back the exposure period in NSW.

"We are working keenly with our colleagues in Victoria to understand the timing of the infection as that has implications for assessing whether there are any other venues."

Dr Chant said contact tracing has so far contacted 243 people who visited the potential exposure sites, including:

She said CCTV footage at the potential exposure sites would be reviewed to do a "full assessment of the risk" that casual contacts had been exposed to.

Dr Chant and NSW Premier Gladys Berejiklian praised South Coast businesses for their COVID-safe plans and use of QR code systems.

"I expect that many people on the South Coast and in Goulburn who have heard the messages from NSW Health [through the QR code sign in app] will also come forward and get tested," Ms Berejiklian said.

"I except to see people in those communities come forward in large numbers and in fact we've boosted our presence down there in terms of testing and I'm confident people in those communities will do so.

"I know that when there was a scare in Batemans Bay recently, that community responded very quickly and very positively, and I'm confident that residents in Goulburn and Jervis Bay and Vincentia will do that today [Wednesday] and tomorrow [Thursday]."

If you attended these venues at the times listed you should get tested and isolate until you receive further information from NSW Health:

The same advice applies to anyone who attended the exposure sites previously announced:

If you attended either of these venues at the times specified, you should get tested and isolate until you receive a negative result:

On Wednesday, the ACT imposed quarantine requirements for anyone in the ACT who attended close contact exposure sites in NSW at the times identified by health authorities.

They must also complete an online declaration form, available on the ACT COVID-19 website, and get tested.

Non-ACT residents who visited an exposure site at the dates and times identified by NSW Health cannot enter the territory without exemption.

In a statement, ACT Health advised Canberrans not currently in the territory to follow the advice of the state they were in.

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