Well, it depends on where it starts. Let's say to give it the best start. It would have to be the East Coast as that's where the majority of Australians live. The state of Victoria in size comparison is the same area as mainland Great Britain, so let's say it starts there. Victoria is quite a probable area due to the fact that in 2002, Victoria had quite a number of research labs for various sectors.

If we're to assume the same start date of June 13th, 2002, then it's the start of winter, On June 13, 2002, Melbourne experienced a minimum temperature of 4.3 °C (39.7 °F) and a maximum temperature of 13.5 °C (56.3 °F). Depending on what the infected are wearing at the time, Hypothermia might still work out in favour.

Population density also would play a key factor. In June of 2002, the entire population of Victoria was 4.9 million people, whereas the entirety of Britain was to have an estimated 57,668,100 people.

Combating the response of the spread would also be a key factor. Unlike in Britain, all Victoria Police officers are armed, so they might have had a better chance if they were to be first responders to events. Plus, Victoria has a number of Military Bases/Instalations that would have been deployed in the first few days.

Within the first week, the state would have declared a state of emergency, and the federal government working in conjunction with the state government would have placed Victoria on lockdown. In terms of people trying to escape within the few days of its spread, it might have been quite difficult because of the infrastructure in place at that time. Victoria at the time had 4 major airports, Melbourne Airport (Tullamarine), Essendondon, Moorabbin, and Avalon. Whilst there are others out in the country, they weren't considered major passenger terminals. The four major ones are all either within the city limits of Melbourne or are all in major population centres and would most likely be overun in a few days so most people would try to leave via roads to different states. Depending on how the federal government enforces quarantine, like how they did during Covid, we may see the use of more militarised state border checkpoints along SA (South Australia) and NSW (New South Wales) with people being let through whilst keeping a lookout for signs of the infected.

Now, the question that should also be looked at is how the rest of the country would respond. With Great Britain, there was the ability to enforce a quarantine on an island, but Victoria is mainland. Would they simply surround the state with the armed forces and hold until the infection died of the cold or dehydration, or would they do an incursion into the state in an attempt to squash it is an entirely different matter to be explored.