Mr Morrison said the situation in Batemans Bay on the NSW South Coast had also "stabilised significantly" after a COVID-19 cluster forced venues across the town to close.

There are now coronavirus outbreaks in 77 Victorian aged care homes - around 10 per cent of the total facilities in the state.

Entire workforces have had to go into isolation, a scenario Mr Morrison said had not been "anticipated or foreshadowed at a state level or considered at a federal level". This is despite past outbreaks in aged care homes causing shortages in staff and PPE, like the Newmarch cluster in NSW.

Australian Defence Force nurses have now been deployed to help in aged care homes across Victoria.

Mr Morrison said the Victorian aged care outbreaks were linked to "broad-based community transmission" of the virus.

There was little community transmission when the Newmarch outbreak occurred, which meant the majority of staff could continue working, Mr Morrison said.

"The challenges of dealing with aged care are not unique to Australia. Indeed in every country in the world where there is sustained community transmission, it is inevitable that this will find its way into aged care facilities," Mr Morrison said.

Health Department secretary Brendan Murphy said on Wednesday given there were around 465 aged care facilities in COVID-19 hot spots, it was a testament to the sector's response that there were not more outbreaks within centres.

Professor Murphy said while the department would investigate "observed breaches" of protocol at sites where there had been significant outbreaks, most outbreaks were inevitable given the level of community transmission.

"These incursions of this virus into facilities are essentially unavoidable," Professor Murphy said.

"The most important thing we can do to solve the residential aged care outbreak in Victoria is to control the community transmission."

Mr Morrison said the aged care royal commission would have scope to examine some of the issues emerging from the aged care outbreaks.

Aggressive testing and contact tracing had also helped bring the NSW outbreak under control, Mr Morrison said.

"It is also pleasing to see that the outbreak in New South Wales has been contained. That has now been the case for many days and again I commend the NSW Government and the excellent tracing work they have been doing to stay on top of that," Mr Morrison said.

"The response down in Batemans Bay has been particularly welcomed and I'm pleased to hear that the situation there has stabilised significantly and the broader cases that have been identified, they have moved on extremely fast to ensure that they can be contained."