Australia's chief scientist says Victoria's contact tracing system was overwhelmed during the state's second wave of coronavirus, with some cases lost or duplicated.
Dr Alan Finkel, who has conducted a review of the nation's contact tracing capabilities, said Victoria's system was only designed to manage low case numbers of infectious diseases such as measles.
"Then you're hit by a pandemic with large numbers that are doubling every four or five days," he told a parliamentary inquiry on Wednesday.
"Unless you are fully prepared for that in terms of training, anticipation and preventative measures to slow the rate of increase in the first place, it's easy to get overwhelmed and yes, Victoria was overwhelmed."
The inquiry has heard Victoria's system was largely paper-based and relied on contact tracers to manually enter information into an IT system.
As a result, Dr Finkel said some COVID-19 cases "weren't being managed end to end, some were lost, duplications occurred".
The Victorian government has since recruited tech giant Salesforce to create a digitised system covering the whole contact tracing process. It will be fully integrated by December.
Six local contact tracing hubs have also been set up across the state.
Dr Finkel said the new system was "more efficient and less error-prone".
He said all Australian states and territories had improved their contact tracing during Victoria's second wave.
All jurisdictions are now training to manage 50 cases for a sustained period per day, per million people.
It means Victoria should be able to manage up to 350 cases per day.
"That's not easy to do, but we do believe it's achievable," Dr Finkel said.
States are also aiming to return COVID-19 test results within 24 hours, while close contacts should be notified within 48 hours.
The benchmarks contrast with the government's response to an outbreak at the Cedar Meats abattoir during the first wave.
Cedar Meats general manager Tony Kairouz told the inquiry one of his workers was refused a COVID-19 test twice.
He said the worker was sent home sick on April 17, but was unable to be tested as he was "not presenting with all the symptoms that would be necessary at the time to warrant a COVID test".
"The third time he went to the doctor he insisted on a COVID test to which the doctor then obliged, that turned out to be positive," Mr Kairouz said.
A second worker tested positive while being treated at Sunshine Hospital after severing his thumb at work on April 23.
Cedar Meats wasn't notified of the cases until April 27.
A total of 111 people connected to the meatworks contracted the virus.
Mr Kairouz said he was disappointed DHHS wouldn't facilitate on-site testing for his workers.
"We knew how difficult it would be to communicate with 350 workers of such diverse backgrounds and language barriers once they left the business. Time was of the essence," he said.
"It would have ensured that detailed and more accurate information was obtained ... Unfortunately, DHHS could not organise this."
Mr Kairouz said delays meant one of his staff members ended up infecting nine others in their family.
"It was a devastating situation," he told the inquiry.
"It was a very difficult time. We were harassed and seen to have done something wrong and that was extremely hard."
Representatives from Colac, Peninsula and Western Health, the University of New South Wales and prominent GP Mukesh Haikerwal also appeared before the Legislative Council Legal and Social Issues Committee on Wednesday.
It is investigating whether the contact tracing system as it stands can handle future coronavirus outbreaks.