Nine people - five workers and four residents have tested positive to COVID-19 at the Penrith aged care home.
"It doesn't matter how mild those symptoms are - runny nose, sore throat, just a scratchy throat in this case - please don't go to work".
NSW Chief Health Officer Dr Kerry Chant told reporters on Wednesday four residents and six staff at Anglicare's Newmarch House at Caddens were now sick with COVID-19 after the unidentified worker battled on with mild symptoms for six days.
"I have spoken to the director of the public health unit and this person is absolutely mortified", Dr Chant told the press conference.
The Anglicare Newmarch House in Caddens, near Penrith, was placed in lockdown on Saturday after the female worker tested positive.
While Dr Chant said the woman "worked whilst she had very mild symptoms", Anglicare Sydney chief executive Grant Millard on Wednesday said she did not display any symptoms during her last shift at the facility.
"We are able to test 5000 patients per day, and while testing for COVID-19 only takes six to eight hours from the arrival of the sample at one of our specialist labs, the sheer volume has meant we haven't been able to get results to patients quickly", she said.
"Nothing was disclosed to us when she was last seen on April 6th, she did not display any symptoms", Mr Millard told ABC TV.
"Strident procedures" were needed to fight an outbreak in a home of elderly residents, she said.
"We can't cast blame automatically, let's wait for the facts", she said.
The entrance to Newmarch House in Sydney's west, where a coronavirus outbreak was started by an infected worker.
Approximately 100 residents - who have an average age of 85 - are isolating in their own rooms. Were they wearing protective gear?
"If we thought there was reckless behaviour, we would report it to other agencies for oversight, but we will go and ask tough questions today", he said.
"People are rightfully upset".
NSW Police Commissioner Mick Fuller told Wednesday's press conference that police officers would visit the facility to talk to management.
Cases of coronavirus in Australia's aged care homes and the wider community have continued to grow, albeit slowly in line with the deceleration in the number of positive cases.
"If we were concerned we would launch an investigation, but at this stage with the information that has been provided, there was no malice in there at all". "It's time for them to be open and transparent", she said.
The woman also worked two shifts at Greystanes Disability Services in Leura. If you are struggling to breathe or experiencing a medical emergency, call 000.