With coronavirus now spreading through populations far from its origins in China, experts say it's become a matter of when — not if — the outbreak becomes a pandemic.

That means it's now time for us all to start preparing, according to University of Queensland virologist Ian Mackay.

"We need to be aware that we are probably heading for that pandemic even if the World Health Organisation doesn't want to call it that yet," Professor Mackay says.

"It's just a matter of time."

Travel bans and quarantine measures have had success in some parts of the world, but the virus has now started killing people in parts of Iran, Italy and South Korea.

Its highly contagious nature is making it difficult to contain.

When will a pandemic be declared?

The World Health Organisation defines a pandemic as "the worldwide spread of a new disease".

It declared a global health emergency last month, but says it's still too early to declare the outbreak a pandemic.

WHO's director-general, Tedros Adhanom Ghebreyesus, says the virus has pandemic potential but, right now, using the word "does not fit the facts but may certainly cause fear".

But that's likely to change if the number of cases keeps growing in Europe, the Middle East and east Asia.

Australia's chief medical officer, Brendan Murphy, says even though the virus doesn't appear to be spreading in Australia for now, "if there is a global pandemic, we will be prepared".

"Every part of the health system is now working on its plan so that we're ready if things develop further in the future," he said at a press conference with the Prime Minister on Tuesday.

Chief medical officer Brendan Murphy says it's difficult to make accurate predictions about the virus. ( AAP: Lukas Coch )

He says it's hard to say when a pandemic will be declared.

"The question will evolve over the next few days to see whether the transmission in those countries can be contained or it's sustained.

"If it is sustained in those countries, as it has been in China, I suspect the WHO would make such a call.

"But at the moment, they're not making that call, because those countries are trying to contain."

What should I do to prepare?

Experts say preparation, not panic, is what's needed now.

"We need to think about whether you have enough medication and essential foods such as canned foods, some pasta or food that can give us fibre, carbohydrate and protein for two weeks, if things were to interrupt the supply chain of food," Professor Mackay says.

"Don't forget to prepare for pets as well, with extra supplies of dried pet food and flea treatments in case there are shortages."

But he cautions against panic-buying supplies or hoarding food.

"We don't want to see empty shelves," he says.

"We have time to prepare now by just buying a few extra supplies each time we shop, and set it aside."

Sharon Lewin, from Melbourne's Peter Doherty Institute for Infection and Immunity, says it'll be even more important for people to get a flu shot before the next flu season.

That's because some people who have contracted the virus overseas have had co-infections, which worsened their conditions.

Italian authorities cut short the Venice Carnival to prevent the virus's spread. ( AP: Luigi Costantini )

What's the Government doing?

Australia declared coronavirus a "disease of pandemic potential" on January 21, Health Minister Greg Hunt says.

That triggered:

The activation of a National Incident Response Centre , to coordinate Australia's response

The activation of a , to coordinate Australia's response The release of masks and other medical equipment from a national medical stockpile

The release of masks and other medical equipment from a AUSMAT — the Australian Medical Assistance Team — being called in. Doctors and nurses from the team have been based with quarantined travellers on Christmas Island and sent on evacuation flights to China.

Last week, the Government published its Health Sector Emergency Response Plan for Novel Coronavirus.

It outlines actions that could be taken in response to a pandemic, including:

Cancelling large gatherings

Asking people to work from home

Asking people to Boosting the capability of hospitals to deal with an increased demand for services, such as increasing intensive care beds

The plan says these measures should be implemented "at a level appropriate for a disease of moderately high impact", because doing too little could have significant consequences.

"Measures will then be scaled up or down as more information becomes known."

Under the plan, state and territory governments are responsible for:

The operation of public health responses

The operation of Undertaking " contact tracing " — that is, identifying people exposed to those who are infected, and following up with them

Undertaking " " — that is, identifying people exposed to those who are infected, and following up with them Coordinating the distribution of antiviral drugs

Coordinating the Bringing in " social distancing " measures (which could include closing schools and workplaces, quarantining people, cancelling events and even shutting down public transport)

Bringing in " " measures (which could include closing schools and workplaces, quarantining people, cancelling events and even shutting down public transport) Implementing infection control guidelines and healthcare safety and quality standards

The states and territories would also "establish systems to promote the safety and security of people in aged care and other institutional settings and support outbreak investigation and management in residential aged care facilities, schools, prisons and other institutions", the report says.

What happens if I catch the virus?

So far, most of the people outside China who have contracted coronavirus have had a mild form of the disease.

"It doesn't look like it is going to cause severe disease in large numbers, but it will in small numbers," Professor Mackay says.

While this coronavirus, formally known as COVID-19, is in the same family as SARS (severe acute respiratory syndrome), it is proving less deadly.

The new virus has a death rate below 2 per cent, while the SARS fatality rate was around 10 per cent.

That means even though many people might be diagnosed with coronavirus, in many people it will be a moderate illness.

But, unlike influenza, there is no effective treatment or vaccine for coronavirus.

The elderly and people with existing health problems are at the highest risk.

"We may see death amongst the elderly, so we need to be thinking about their care," Professor Mackay says.

"We need to make sure they have their medications up to date, have food as well, and talk to the care facilities about what its plans are for something like this pandemic."

As well as following good personal hygiene such as hand washing, experts say we should pay close attention to the advice of local and national public health authorities.

"They are doing a lot of work behind the scenes to make sure we will be as protected as possible."

So, how worried should I be?

Prime Minister Scott Morrison says travel bans and quarantine measures have been "very effective" here, and Australians can confidently go about their daily lives as normal.

"In Australia, there is no great risk at this point in time when it comes to human transmission, given the 15 cases [from Wuhan] that were identified have all been cleared and the remaining seven are mild cases, and they are in isolation."

Professor Sharon Lewin is the director of the Doherty Institute for Infection and Immunity. It was the first place to grow COVID-19 outside of China.

She agrees Australia has good plans in place.

"We are an island, but we're not isolated from the rest of the world, so it's not feasible that we can completely isolate ourselves," Professor Lewin says.

"There's been a lot of very detailed thinking of what will happen in the containment phase, which is what we're doing now — where are the labs up to, diagnosis, how would we handle stockpiles of masks and gloves?"

She says major pandemic measures, such as mass school closures and major event cancellations, haven't been taken in Australia before.

"We will be guided by federal and state health departments, but there is absolutely no need to start thinking about that now."

The chief medical officer says there are still a lot of unknowns.

"One of the things I've learned about this virus is it's very hard to predict anything, other than making a daily evaluation of the facts," Professor Murphy says.