An 82-year-old man living in a Sydney aged care facility has tested positive to the coronavirus.

The news came hours after it was confirmed a nurse working at the Dorothy Henderson Lodge in Macquarie Park had also tested positive for the virus.

NSW Health Minister Brad Hazzard on Wednesday confirmed the "much-loved" worker at BaptistCare's Dorothy Henderson Lodge in Macquarie Park has been diagnosed with coronavirus.

Health authorities say it's "unfortunate" the employee may have been working while ill, putting elderly residents at risk.

The woman is aged in her 50s and hasn't recently travelled outside Australia.

She started experiencing flu-like symptoms around 24 February and is now in a stable condition in hospital, Mr Hazzard said.

Eleven of the 13 residents for whom she was carer have been placed in isolation.

One of the residents, a 95-year-old woman, has died following a respiratory illness, with authorities expected to confirm later on Wednesday if her death was COVID-19-related.

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Australia's chief medical officer, Professor Brendan Murphy called the situation "very unfortunate".

NSW chief health officer Dr Kerry Chant says aged care facilities often have residents with serious underlying health conditions who are more likely to experience more severe disease.

Dr Chant said she was satisfied there was no need to lock down the entire facility.

The aged care worker had a relationship with a smaller group of residents in the facility, rather than a more general exposure, she said.

"Notwithstanding, we are taking this matter very seriously."

She added that the aged care worker, who is being treated at Royal North Shore Hospital, is "much-loved" and has worked at the facility for more than two decades

Seven additional people in the past 24 hours have tested positive for COVID-19 bringing the total number of those infected in NSW to 16.

NSW Health is alerting passengers who were on five separate flights from Asia in the past week after two men in their 30s, a man in his 50s and two women in their 60s tested positive following their arrival in NSW.

They travelled from Iran, Japan, South Korea and Singapore.

Premier Gladys Berejiklian on Wednesday warned the number of COVID-19 cases was likely to rise in the next few days.