"We've reached a point in our health system where it's juggling severe workforce shortages."
The "code brown" has been activated for all hospitals in metropolitan Melbourne, as well as at Barwon Health, Grampians Health, Bendigo Health, Goulburn Valley Health, Albury Wodonga Health and Latrobe Regional Hospital.
Under the measure, hospitals will be able to defer non-urgent services and cancel planned leave for staff, as well as redeploy workers.
Services will also be changed to free-up staff, including the delivery of outpatient services outside of the hospital, meaning workers may perform different roles.
Health services will also be able to prioritise offloading ambulance patients at emergency departments to get paramedics on the road.
Austin Health CEO Adam Horsburgh said Covid-related hospital admissions were approaching 1500 per day, and thousands of workers were not available to work.
He said the code brown would allow health services to focus on and prioritise access for urgent patients.
"This is about prioritising emergency and urgent care services," he said.
He said staff being asked to defer leave would be the subject of individual discussions between health services and workers.
"That's a decision to be taken at an individual hospital level and it will be a decision that's only taken if it's absolutely necessary," he said.
"We're all conscious of how tired and fatigued our workforce are and this situation will be facing us for several weeks ahead.
"Over the past two years, we've asked an awful lot of our health care staff and over the coming weeks, we may have to ask even more of them."
Royal Melbourne Hospital head emergency department nurse Susan Harding said the system had faced severe pressure in recent weeks.
She emphasised it was important for people to only approach emergency departments if it was absolutely necessary.
"We had a patient last week that was desperate for a PCR. They called triple-0, called an ambulance under the guise of having chest pain, they presented to the emergency department and were fast-tracked down to a resuscitation room at which point they declared they didn't have chest pain and that they really wanted a PCR and wanted it quickly," she said.
"That is an unbelievable misuse of resources and we are asking people to make good decisions.
"I think we've been challenged in the last couple of weeks and what we don't want to do is put our health care service under pressure."
