Workers in high-risk settings such as hospitals and aged care will be told not to attend work for 14-days if they recently travelled in the greater Sydney or Newcastle area.
ACT Health has advised workers in areas such as hospitals, aged care and prisons to avoid the high-risk areas for 14-days from leaving those regions.
Last month, ACT Health told high-risk workers who had recently returned from the local government areas of Fairfield, Campbelltown and Liverpool, to not attend work.
The advice has been extended to include all of greater Sydney and Newcastle.
The advice includes staff, volunteers and visitors of hospitals, residential aged care, correctional facilities and residential accommodation facilities which provide care to vulnerable people.
These workers, volunteers and visitors are asked to be alert for COVID-19 symptoms such as a fever and dry cough, and if symptoms develop, to immediately self-isolate at home and arrange to get tested.
General practitioners and other community health practitioners can continue to deliver services but should monitor their health.
"If you have visited locations identified by NSW Health as having cases of COVID-19, particularly around Newcastle or Greater Sydney, please follow the advice being provided by the New South Wales authorities," Dr Johnston said.
NSW reported 14 new cases of COVID-19 in the 24 hours to 8pm on Sunday.
NSW chief health officer Dr Kerry Chant on Monday encouraged residents to avoid large gatherings and excessive socialising.