When COVID-19 hit Australia, the country's top health bureaucrats were bracing for something big - but even they were yet to grasp the enormity of the looming crisis.

It was January 25, 2020 - the day before Australia Day - when authorities confirmed the country's first case, a man from Wuhan in China's Hubei province who flew into Melbourne.

Weeks before, then acting-chief medical officer Paul Kelly was sitting in a room at Canberra's National Incident Centre encased in thick smoke from the Black Summer bushfires that burned near the capital.

It was there he heard about an unusual cluster of what sounded like pneumonia in Wuhan.

"I had to look up where that was," Professor Kelly tells AAP.

"It sounded like something new and eerily like the first SARS - I was worried immediately that this could be big."

This Thursday marks 1000 days since the announcement of Australia's first case, which also signalled the start of a spiral of anxiety and fear across the nation.

On February 27, 2020 the government declared COVID-19 would be a pandemic - nearly a fortnight before the World Health Organisation made the same call globally.

Previously little-known health officials were thrown into the spotlight as the public hungered for information about the coronavirus and as state and federal governments imposed ever-stricter measures to curb its spread.

For some, like Alfred Health infectious diseases physician Allen Cheng, it was a difficult transition. He took on the role of Victoria's deputy chief health officer in July 2020.

"I'm a doctor - I'm used to making decisions that affect the one patient in front of me," Professor Cheng says.

"To make a decision that I'm going to shut a border or I'm going to cause everyone to stay at home - that's another level of decision-making, and certainly that's very stressful."

Australia's first COVID-related death came on March 1 in Western Australia - a jurisdiction that would go on to have among the country's fewest days in lockdown but the most arduous border restrictions.

The health crisis snowballed after March 19, when the Ruby Princess cruise ship docked in Sydney after a fateful 11-day round trip to New Zealand. It would go on to be linked to 28 COVID-related deaths and hundreds of cases.

Australia closed its borders to non-citizens and non-residents on March 20, with some states and territories having already moved to restrict the size of gatherings and introduce social-distancing measures.

Within a week, governments were telling Australians to stay at home unless they were heading out for essential reasons, with cross-border movements also curbed.

Health professionals and the media fixated on outbreaks in countries such as Italy, where COVID-19 was ravaging the population and local newspapers were filling their pages with obituaries.

Still, most experts were confident Australia would come through the other side of the pandemic.

Prof Cheng says a lot of people are looking back on the country's approach and questioning whether lockdowns were justified, but many deaths were avoided by stamping out the virus until vaccines became available.

"Some of the first clarity of messaging could have been done better," he says.

"There's a tendency when you're in the thick of it to get caught in the weeds and you don't really spell out the big picture."

ACT Chief Health Officer Kerryn Coleman adds: "You never think that something this big is going to arrive in your lifetime.

"(I would) beg of people to remember when you're considering some of those decisions and things that we did, that the context is really important."

Ultimately, Melbourne would be subject to six lockdowns of a cumulative 260-plus days, giving the Victorian capital the dubious honour of being dubbed the most locked-down city in the world.

NSW clocked up the second-most days in lockdown of any Australian jurisdiction, with about 150. Tasmania spent about 50 days in lockdown, as did South Australia, according to data tracker CovidBaseAU.

Prof Kelly says he had confidence in Australians' resilience and the health system's unsung heroes, but he acknowledges the crisis became overwhelming at times due to the unquenchable demand for advice and information.

"There was constant scrutiny in what was the first global pandemic since social media has become ever-present in our lives," he says.

Queensland Chief Health Officer John Gerrard points out there was never a guarantee a safe and effective vaccine would be developed and Australia could easily have lost control of the virus once the Omicron variant emerged in 2021.

"An unvaccinated Australian population would then have experienced the full impact of the pandemic," Dr Gerrard says.

"That would have been a disaster."

The UK and US began mass-vaccination programs in December 2020, while in Australia the country's now-infamously slow initial rollout began in mid-February.

Australia hit 100 COVID-related deaths in May 2020, surpassed 1000 deaths more than 15 months later in August 2021 and reached 10,000 deaths in July this year.

More than 10 million cases of the coronavirus have been recorded in the nearly 1000 days since the country's first.

Despite the thousands of fatal cases recorded in Australia, Prof Cheng says the national death toll from COVID-19 would have been more like 80,000 if the virus had been allowed to get out of control as happened in the UK and US.

"The first thing that we always used to teach is what we call the social determinants of health. So, poor people get it badly in any disease ... and that's no different for COVID," he says.

"What I've learned professionally is that there are things that we can do to fix that problem."

Many health officials are cautiously optimistic the country can handle future COVID-19 waves and variants, and is now better-equipped to deal with pandemics.

Prof Kelly says it's vital authorities continue to monitor for emerging disease and strengthen surveillance systems.

"The price of survival is eternal vigilance," he says.

NATIONAL COVID-19 DATA

Cases: 10.3 million

Deaths: More than 15,400

Vaccinations: 63.7 million

*All data based on most recent figures available on Friday, October 14