China Southern Airlines Flight 321 touched down in Melbourne from Guangzhou on January 19.

On board was a 58-year-old man from Wuhan, who five days after arriving in Australia presented to a local GP with a fever, cough and shortness of breath.

He had COVID-19 and was the first known case of the deadly and highly transmissible disease in our country.

WATCH: The preview for Four Corners last night. Post continues after video.

Despite being well prepared – calling ahead to the Monash Medical Centre and wearing a mask on arrival (he was well aware of the disease’s prevalence in his home country) – he’d already been in the Melbourne community for a week.

The same day the man was confirmed as being COVID-19 positive, three more people were diagnosed in Sydney.

They’d all flown in from Wuhan.

Two days later, a 21-year-old from Wuhan – studying at the University of New South Wales – tested positive.

Then, a man and a woman from a Wuhan tour group who had flown into the Gold Coast were confirmed as positive.

COVID-19 started on our shores with these seven people, and now it’s infected more than 4000, killing 19.

But as Professor Sharon Lewin, Director of the Doherty Institute, explained onFour Cornerslast night: “there was no reason we were going to be protected” from this virus given the high number of Chinese tourists and students that frequent our country.

The spread of the virus to every state and territory in Australia – was in Dr Norman Swan’s opinion – because of a series of mistakes, fiascos and mishandlings.

Chief Medical Officer Dr Brendan Murphy has defended the government's positioning on Four Corners. Image: ABC.

Chief Medical Officer Professor Brendan Murphy told theABC, he thinks Australia was quick to put in border control restrictions with China, but Professor Lewin says that by the time those restrictions came in, there had already been enormous amounts of travel into and out of Australia.

"You only need one case. That's how it got around," she said. "Every infected person infects two others, so you can imagine how quickly that can grow."

Daley says because of that, we've got no chance of tracing and tracking the true number of cases that have spread their way around our country.

On February 27, we were told by Prime Minister Scott Morrison there was every indication we were headed towards a pandemic, but he also told Australians "you can still go to the football, you can still go to the cricket, you can still go and play with your friends in the street. You can do all of these things because Australia has acted quickly".

Dr Norman Swan says the government's decision making was "public relations Valium." Image: ABC.

Dr Andrew Miller, President of the Australian Medical Association WA, added that, "the way that our media and politics works is that everyone comments on everything, pretty much. They are in that cycle of putting that spin on it that suits the particular person who is delivering the message. And they have a lot of media advisers to tell them what to say. That's not the way to deal with a health crisis".

Two days later, the first case of community transmission in Australia was recorded, and it's at this point that it becomes too hard to shut down the chains of transmission, because you can no longer identify them.

It's at this point, other countries shut down.

Professor Dale Fisher, Chair of the WHO Global Outbreak Alert and Response Network.

On March 1, the first Australian death was recorded. But huge Australian events were still going ahead, despite the growing risks.

The current COVID-19 figures.

A Super Rugby game, and the T20 Women's World Cup final - which saw 86,000 people attend - are just two examples.

Professor Brendan Murphy says in hindsight perhaps the big events should have been called off quicker, but "things were moving so rapidly. At that time the risk of transmission of cases in large crowds was very low".

Even Scott Morrison was planning to go to a football game the following Saturday.

As the spread grows in Australia, we're already running out of testing kits (and those that meet the testing criteria are slim) which means we're not practicing the most effective way to break the chains of transmissions - test, test, test, and isolate the cases.

The numbers for #covid will only go in one direction in WA for some time now. There is no flattening yet. https://t.co/dOhPCAUFNe

— Andrew Miller (@drajm) March 30, 2020

Then you add in the fact Sydney allowed the Ruby Princess cruise ship to disembark without stringent testing - two people have since died and 215 from that ship have tested positive to coronavirus, and thousands continued to flock to the coastline's beaches despite strict social distancing rules closing in.

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Victorians at the beach on Friday, a week after Bondi Beach goers were slammed for doing the same thing - ignoring social distancing rules. Image: Robert Cianflone/Getty Images.

There's a fear - if that happens - our healthcare professionals will start to be infected and die, like we've seen in countries like Italy, as supply reserves get thinner and thinner.

Professor Lewin thinks we've got two outcomes ahead of us: we are able to flatten the curve - which she thinks is possible - or we turn out like Italy and the US.

As far as the experts are concerned, we can't take a soft approach. The message remains: stay home at all costs.

Feature image: Getty.

To protect yourself and the community from COVID-19, keep at least 1.5 metres away from other people, regularly wash your hands and avoid touching your face. If you are sick and believe you have symptoms of COVID-19, call your GP ahead of time to book an appointment. Or call the national Coronavirus Health Information Line for advice on 1800 020 080. If you are experiencing a medical emergency, call 000. To keep up to date with the latest information, please visit the Department of Health website .