It's hard to believe how much life has changed in a week.

Seven days ago most international visitors could still enter Australia. Mainlanders could visit Tasmania.

Crowds were still gathering at the footy, at concerts and stage shows. Supermarkets and pharmacies weren't limiting how many goods shoppers could buy.

Classrooms and workplaces were mostly full and 20,000 Qantas staff were still gainfully employed.

Nine days ago the Prime Minister was still musing about going to watch his beloved Sharkies and some of us were happily shaking hands.

It all seems a world away now.

What if these measures fail?

Underpinning this rapid and extraordinary disruption to our economy and society has been the dreaded curve. The line graph showing how fast the coronavirus caseload is growing. It's the only data set that really matters right now.

Coronavirus infections are rising exponentially in Australia. ( ABC News )

Analysing and assessing the Government's performance during an unprecedented crisis like this is complicated.

Leaders around the world are making difficult decisions about how to protect the health of their people without destroying economies and risking social breakdown.

None of them are charting a perfect course. This is not a time to demand fixed positions, but rather some flexibility as new evidence and information becomes available.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 25 seconds 1 m 25 s Scott Morrison urges people to stop hoarding food supplies

It's still important to weigh the merits of each step being taken and there's understandable interest in the Prime Minister's language and tone.

But in the end, the best measure of success or failure is ultimately that caseload curve.

This week, Australia's curve was far too vertical. The much-talked-about "flattening" is not happening yet.

The number of coronavirus cases in Australia quadrupled in a week. That rate of growth cannot be allowed to continue.

Most of the cases have come from overseas or are directly connected to someone who's been abroad, hence the ban on all non-citizens and residents entering Australia.

Let's hope shutting the borders works, along with the indoor and outdoor crowd bans and social-distancing venue limits.

But what if all these measures fail to flatten the curve? What then?

Stay up-to-date on the coronavirus outbreak Download the ABC News app and subscribe to our range of news alerts for the latest on how the pandemic is impacting the world

Nothing should be set in stone

Many countries have gone a lot further than Australia, with mixed results.

The complete lockdowns in Italy, France and Spain are yet to flatten their respective curves, but in China's Hubei province the lengthy enforced lockdown has slowed the spread of the virus dramatically.

Other jurisdictions clearly think closing everyone's doors is worth a try, despite the heavy social and economic toll.

On Friday, the US state of California ordered its 40 million residents to stay at home. Even Hollywood has ground to a halt.

Australia's National Cabinet of federal and state leaders is reluctant to take this huge step. The Prime Minister rightly warns this crisis is likely to run for at least six months. The idea we can shut down for merely two or four weeks offers false promise.

The National Cabinet is, however, inching closer to social closure.

After meeting his colleagues on Friday, the Prime Minister warned we could see school closures or even localised lockdowns in areas where the virus is running rampant.

Parts of Sydney or Melbourne could be shut down for example — it doesn't mean Gundagai or Geraldton has to follow suit.

Today Scott Morrison and Josh Frydenberg will unveil what's being billed as a huge economic rescue package for small businesses, sole traders and workers facing ruin. It follows the first stimulus package only a week ago and it's unlikely to be the last.

This is an unprecedented challenge for state and federal governments and it requires an evolving response. Nothing should be set in stone.

It all depends on that dreaded curve.

David Speers is the host of Insiders, which airs on ABC TV at 9am on Sunday or on iview.