Experts say it will be Easter before we know whether what we have been doing to limit the spread of coronavirus is working.

There are now more than 400,000 cases in 169 countries and almost 19,000 people have died from COVID-19. In Australia, there are more than 3,000 cases and 13 people have died.

Governments have implemented a range of measures to tackle the spread of the virus. Some have opted for tightly controlled lockdowns, like India and New Zealand. Others have been slower to respond and have taken a less stringent approach.

In Australia the focus has been on flattening the curve.

People are being asked to stay at home as much as possible and only those in essential industries are meant to be turning up to their places of work.

Data shows the success of Australia’s plan to fight coronavirus relies mostly on reducing the speed of its spread, and the numbers are tight.

The modelling says it will move through the population rapidly unless at least eight in 10 Australians stay home as much as possible.

If that drops to just seven in 10 people it will be very difficult to flatten the curve.

The intersection outside Flinders Street station in Melbourne is usually one of the busiest in the city. Photo: ABC News/Ron Ekkel

Is the plan working?

But even if the fight is going well, how long will it be until we know that?

Medical experts say we will need to wait weeks for an answer.

Hassan Vally, associate professor of public health at La Trobe University, said that is due to the long incubation period of coronavirus.

“It’s going to take some time for us to know whether our public health interventions, including social distancing, are actually working and of course, the only measure of that will be how many cases we see about 10 days to two weeks from now,” he said.

“The biggest worry, of course, is that we get a nasty surprise two weeks from now and find out that what we’ve been doing hasn’t been working.

“And then we’re in a bit of a situation where we’re going to ramp everything up very quickly.”

Professor Michael Kidd from the Chief Medical Officer’s team said reduced numbers of new cases across NSW and Victoria in the past few days had shown that self-isolation and social distancing has been working.

“It’s working but we can’t take the level of comfort that I think you are wanting to take from seeing numbers going down slightly over a 24-hour period,” he told Channel Nine this morning.

“We have to be watching the trend over many weeks.”

NSW Chief Medical Officer Kerry Chant also indicated that it would be up to a fortnight before it was clear if what Australians are being told to do was helping to stop the spread of coronavirus.

Without a vaccine or treatment available, the uncertainty is likely to continue, Professor Vally said.

“We’re now at a point where the biggest influence on how this is going to play out are individuals,” he said.

“It’s how well people will listen to the advice to practise social-distancing measures, because that is going to be the greatest influence on how much this virus is transmitted.”

Restrictions and measures in place

On Friday the National Cabinet announced further restrictions, mostly around quarantine provisions and enforcement.

From midnight on Saturday, everyone arriving by plane will be quarantined in hotels and other facilities for two weeks, in the city in which they arrive.

The Australian Defence Force will also be deployed to assist police with enforcing self-isolation and quarantine measures.

Here’s a list of the other measures, which were introduced on Wednesday:

Activities and business to be shut down:

Australian citizens travelling overseas (with strict exemptions)
Amusement parks and arcades
Indoor and outdoor play centres
Community and recreation centres, health clubs, fitness centres, yoga, barre, spin facilities, saunas, wellness centres
Public swimming pools
Galleries, museums, national institutions, historic sites, libraries, community centres
Auction houses
Real estate auctions and open house inspections
In-store beauty therapy, tanning, waxing, nail salons and tattoo parlours, spa and massage parlours (excluding allied-health-related services, like physiotherapy)
Food courts within shopping centres will only be able to sell takeaway. Shopping centres themselves will remain open

Limits on weddings, funerals and exercise:

Personal training and boot camps are limited to a maximum of 10 people
Weddings can continue, but only with the couple, the celebrant, and witnesses totalling a maximum of five people
Funerals are limited to a maximum of 10 people
Outdoor and indoor food markets will be addressed by individual states and territories

Businesses remaining open:

Cafes and restaurants (only takeaway and delivery)
Hotels (only accommodation)
Supermarkets
Banks
Petrol stations
Pharmacies
Convenience stores
Freight and logistics
Food delivery
Bottle shops
Hairdressers and barbers
The first stage of restrictions forced the shut down of venues including clubs, pubs, sporting venues and places of worship.

–ABC