"Anyone on that flight … should be very aware that there was someone on the flight who had the coronavirus," NSW Health Minister Brad Hazzard said at a press conference on Monday.

The woman did not keep her flight ticket and her seat number is not known, NSW Chief Health Officer Kerry Chant said.

NSW Health is in contact with the airline to determine where she sat and to identify passengers who sat in the two rows in front of, and behind, her to alert them to the possibility that they may have been exposed to the coronavirus, Dr Chant said.

Those "close contacts" will be asked to self-isolate for 14 days, she said. "We will be reaching out as soon as we have [their] contact details."

Mr Hazzard said any passengers on the flight with flu-like symptoms should contact their doctor.

"If you have any doubts or thoughts that [it] may be the coronavirus, please ring ahead to your GP or ring ahead to the local emergency department so they are aware and can take the appropriate steps to keep everyone safe," he said.