Director of emergency medicine Dr Shamus Shepherd said people should avoid the hospital unless absolutely necessary as staff prepare for a peak in cases.

The hot zone, treating COVID-19 and other respiratory conditions, will take over the existing ED and the cold zone, for all other conditions, will be adapted from other hospital departments.

The main entrance to the hospital will be closed, meaning everyone would need to go to a checkpoint in front of the emergency department.

He said people would be greeted by a health worker in full protective equipment and directed accordingly - emergency patients without coronavirus symptoms will likely be allowed one loved one to stay with them while those with will not.

"No visitors will be permitted into the hot zone," he said.

He said the main challenge for the cold zone was it was not built for purpose, which would place limitations on the care given.

He also said while some equipment could be split between the two zones, the hospital only had one of others.

"It's going to affect the level of care because you can't walk into the hot zone and use it in the cold zone," he said.

"We have to work out how to manage those."

Dr Shepherd said the other concern was staffing to man the ventilators and beds because any staff with symptoms would need to be kept home.

"We know 10-15 per cent of health workers will get COVID - that's been the overseas experience," he said.

"We're expecting quite a high attrition rate and there will be a need to flex and flux depending on what the needs are."

Dr Shepherd said it could mean health professionals might be called upon from outside the hospital's payroll to help out.

He said health services were planning based on between 10 and 40 per cent of the population contracting the virus - the number will depend on how well people in the community practise social distancing and self-isolate after returning from overseas.

"Twenty per cent of those will need hospital admission and 5 per cent will need critical care," he said.

"The numbers are a bit scary, depending on how you look at them."

Dr Shepherd said the best way the public could help was continuing to follow health advice by washing hands regularly, coughing into their elbow and only attending the hospital where absolutely necessary.

He also urged people to get the flu shot.

"It won't just be the volume of COVID patients, it's going to overlap the flu season and it's predicted to be a bad one this year," he said.

Dr Shepherd said pharmacies and GPs were well equipped to handle less urgent problems and GPs were offering telehealth appointments.

But he said doctors were distressed at the lack of diligence from some younger members of the community, thinking it would only affect older people.

"If we're overwhelmed, we won't be able to treat appendicitis, car accidents, injuries and the things young people still get," he said.

"This isn't a problem for one part of society."

The health service is prepared for the ED changes to last six months - they are unprecedented in Orange and will be replicated across the region.

Dr Shepherd said health services across the state had learned from overseas experiences.

"A lot of experiences, particularly in Europe and North America show that if you don't over-prepare early, once the wave arrives, you don't get a second chance to get control over it," he said.

"We're hoping for the best, but preparing for the worst."