During Victoria's second wave of the virus in July 2020, 45 residents at St Basil's Home for the Aged died of COVID-19, after regular workers at the home were declared close contacts and replaced by inexperienced agency staff.

In an email sent 48 hours after the handover, Dr Ellen Maxwell said "the situation at this nursing home needs to be escalated to the highest level in the state health department".

She complained that the basic needs of residents were not being attended to, and the safety of her staff was being compromised.

On July 23 as the outbreak took off, Melbourne Pathology was contracted to conduct on-site testing for 108 residents, 120 regular workers who had been deemed close contacts and about 60 surge staff.

But only 36 staff initially presented for testing - and most of them had already been infected.

"It was a very sad surprise to us that we got 28 positives from our first day of testing at St Basil's," Dr Maxwell said.

Also on Monday, the inquest heard there were infection control breaches and a lack of food and medicine for residents within hours of the workforce transfer.

A cook at St Basil's, Connie Apidopoulos, said the elderly residents at St Basil's were "like our parents," and the home was usually a warm and kind place to work.

She usually kept up to date records of the special food and drink each resident needed, but on July 22, the day new staff took over, she had just a few hours to brief a replacement worker who had no prior experience.

"I will never forget that day ... very stressful, we didn't know what was going on," Ms Apidopoulos told the inquest.

Despite informing her supervisor she was worried about the short handover, she was told she had to be out of the kitchen by 11am.

Staying on in a nearby lounge room, she saw new staff breaching infection controls, such as collecting food trays from rooms with infected residents and bringing them into the kitchen.

By 1.30pm residents had missed lunch and had not been given their medication, she said.

"They were coming out from their rooms, very stressed, looking for medications, looking for food ... it was a disaster."

In her police statement, Ms Apidopoulos described returning to the home about a fortnight later, to find food smelling and rotting in the fridge, and thickened drinks she had prepared the morning of the handover.

"They hadn't been touched. I couldn't believe my eyes. I was shocked," she said.

But Naveen Tenneti - who oversaw public health policy for high risk settings as part of the state's COVID-19 response - said most, if not all, staff and residents would have caught the virus had staff not been ordered to isolate.

"There would have been more cases and more deaths," he said.

Dr Tenneti testified the decision to furlough workers was appropriate and made after tests showed "significant and worrisome" levels of transmission at the home.

He rejected suggestions health authorities had reacted to the outbreak too late, or that the quarantine order was a "whiplash" response.

He said the orders were based on assumptions that the surge workforce would be big enough and have the skills to do the job, and St Basil's would co-operate.

Dr Tenneti said if he had known the surge workforce could not meet basic standards, the quarantine orders would have been re-evaluated.

The hearing continues before Victorian State Coroner John Cain.

Australian Associated Press