Coronavirus has officially been declared a pandemic but health authorities in Australia have called for calm, reiterating that a runny nose or scratchy throat does not mean you have COVID-19.

In a sample group of 100 people with coronavirus, about 80 will have only minor symptoms, if any at all.

About 15 people will have more serious symptoms that could be similar to severe influenza and between one and three people out of 100 may die as a result of pneumonia and respiratory complications.

Here, infectious disease specialist Dr William Rawlinson breaks down how coronavirus attacks the body, when people should seek help, and what recovery looks like.

What are the symptoms?

Most people who are infected by coronavirus feel like they have a common cold.

The most common symptoms are fever, sore throat, dry cough and fatigue but some also have headaches, nasal congestion or a runny nose.

Diarrhea and nausea have also been reported but are less common.

Symptoms will generally appear three to four days after exposure to the virus but can be up to 14 days later.

In serious cases, the symptoms will be similar to influenza, Dr Rawlinson said.

"They may see changes on their X-ray, they might get pneumonia," Dr Rawlinson said.

"Some, at the much more severe end, will need to go to ICU but that is a very small percentage."

Although it is less likely, some people who contract COVID-19 don't develop any symptoms or feel unwell in any way.

Will I get it?

If you are suspicious about your health for any reason you should contact your GP or call the national coronavirus information line on 1800 020 080.

Dr Rawlinson says it is essential that you call your GP ahead of time so the clinic can prepare for your arrival.

"I think a conversation with a sensible health care professional can make a big difference to how you see yourself and can direct you in the right way very quickly."

Whether you are eligible for coronavirus testing depends on where you live as the criteria differs between states and territories so check your relevant health department's website.

People in Australia are generally in a strong position to fight coronavirus due to our population size, health outcomes and good diet.

A high temperature is a symptom, but not proof of COVID-19. ( AAP: David Mariuz )

Those under 18 are less susceptible to the virus, according to the limited clinical reports available.

Dr Rawlinson says those over 65 are at higher risk of more severe symptoms as are those with pre-existing conditions like heart disease or asthma.

However, the mortality rate is highest among people over 80.

As opposed to the influenza outbreak in 2009, pregnant women do not seem to be at greater risk of contracting coronavirus.

When will I recover?

About 80 per cent of people recover from the disease without any special treatment.

"If [you] have COVID-19, don't be overwhelmed by it. By far and away, people are recovering well," Dr Rawlinson said.

Most people with minor symptoms will be told to quarantine themselves at home, keep up fluids and take paracetamol to control their temperature.

Australian patients have generally recovered in about four weeks, Dr Rawlinson said.

The people who suffer more severe symptoms may require hospital admission, where they will be cared for in a negative pressure ward and might be given intravenous fluids or oxygen in more serious cases.

Some may develop an infection in their lower respiratory tract which could lead to pneumonia.

These patients would be treated in an intensive care unit where high-flow oxygen may be administered or they may be intubated.

Severe pneumonia can lead to respiratory failure, which is the leading cause of death from coronavirus.