Thousands of Sydneysiders will potentially have to self-isolate for two weeks after a pub staffer and three other people became the latest cases in an emerging coronavirus cluster.
The 18-year-old staffer and a close contact in her 50s, plus a woman in her 40s and a Victorian man in his 20s, who both dined at the venue, were on Sunday confirmed as new cases linked to The Crossroads Hotel cluster.
It led authorities to vastly expand the requirement on patrons of the Casula pub to self-isolate from the 600-odd people who visited on July 3 to everyone who entered from July 3 to its closure on July 10.
The original case is still not known, NSW Chief Health Officer Kerry Chant said.
"We do not think the staff member was the source," Dr Chant told reporters on Sunday.
"He worked for a number of days, he did work on the 3rd (and) on subsequent days."
Five cases have been previously linked to the pub - two patrons who visited on July 3 and three close contacts of one of those patrons.
None of those cases is linked to Victoria's outbreak.
Some 1200 people have been tested at the pop-up clinic in the pub car park since Friday.
Dr Chant said all Crossroads patrons and staff should get tested as a precaution and self-isolate for 14 days since their last visit.
"Even if you get a negative test, that does not mean you are out of the woods," she said.
"A negative result does not mean you can breach self-isolation."
Premier Gladys Berejiklian said the state was on high alert for community transmission.
"I get extremely concerned and upset when we see people flouting the rules that are in place because that will take us down the path of Victoria," she said.
"If you wake up with a scratchy throat, don't go to work. Get tested and stay home."
The pub outbreak highlighted the importance of businesses recording contact details for every sit-down customer and the public taking the measures seriously, Dr Chant said.
"When you do go into cafes, restaurants and other facilities, there is a reason we ask you for those details," the state's top doctor said.
"Please use correct numbers (and) write legibly because this will be in your best interest."
The staffer's positive result was returned late on Saturday, meaning he's not yet included in NSW's official total of 3289.
The other new cases are also not yet included in the tally.
Five cases were officially added on Sunday - three household contacts of a Crossroads patron and two returned travellers.
Another case was removed after expert analysis.
Ms Berejiklian also announced on Sunday that NSW would begin charging international arrivals for their mandatory 14-day stay in hotel quarantine.
From Saturday, for all arrivals on tickets bought from midnight Monday, the first adult in each travelling party will be charged $3000.
Subsequent adults will be billed $1000, each child $500 while kids under three will continue to be free.
Exemptions will be permitted in some circumstances.
Australian Associated Press