Explainer: How do I know if I have COVID-19?

The respiratory illness has spread rapidly around the world and brought us into a period of uncertainty.

But how do you know if you have COVID-19?

It is a respiratory illness and the main signs of COVID-19 is a fever, cough, sore throat and a shortness of breath, according to the Department of Health.

The initial symptoms of each of these illnesses are similar.

It is uncommon to develop a fever when you have a cold. So if you do have a high fever it is likely not the common cold.

But to add to confusion a mild case of coronavirus can have the same symptoms as the common cold.

COVID-19 and the flu have similar symptoms and are transmitted in the same way, however, incubation periods differ.

The average time from infection to appearance of symptoms for the flu is about two days.

The verdict is still out on the COVID-19 incubation period, but a study, published in Annals of Internal Medicine, found 97.5 per cent of those who developed symptoms would do so within 11.5 days (hence 14-day quarantines).

There also appears to be more severe cases of COVID-19 with about 5 per cent of those affected admitted to intensive care units, according to NSW Health.

Person-to-person transmission in Australia is very low at the moment and measures, such as cancelling mass gatherings of more than 500 people, will help to keep it this way.

Of course this is a fluid situation so this advice may be completely different tomorrow.

A throat and nose swab test will reveal if you have COVID-19 but you have to meet certain criteria for being tested.

If you have COVID-19 symptoms and have either been overseas in the past 14 days, or have had close contact with a confirmed case it is recommended you get a test.

However, the Department of Health said other criteria for testing includes those with a fever or acute respiratory infection (with or without a fever), a severe case of community-acquired pneumonia with no cause that can be determined by a doctor or if you are a healthcare worker with symptoms.

The virus spreads from person to person.

This can be via close contact with an infectious person, this includes in the 24 hours before they show symptoms.

Droplets from an infected person's sneeze or cough is another main way the virus spreads, particularly if these droplets are left on benches and doorknobs, which another person touches.

The World Health Organisation says it's not known how long COVID-19 survives on surfaces but it could stay there from anywhere for a few hours or up to several days, like other coronaviruses.

Practicing good hand hygiene is one of the most effective preventative measures against COVID-19. This means washing your hands regularly with soap and water - before and after eating and after going to the toilet.

You should also keep your hands away from your face - touching your nose or mouth poses the possibility of ingesting germs.

If you have to cough or sneeze you should do it into your elbow.

But it's also important you keep areas clean. Make sure you throw out used tissues and disinfect bench tops, desks and dining tables regularly.

More importantly, as many experts have pointed out, now is the time to practice social distancing.

This can be done by staying at least 1.5m away from people, avoiding mass gatherings, working from home if you can and reducing visits to people at higher risk of developing symptoms, for example residential aged care facilities.

You should only wear a mask if you have symptoms in order to keep stockpiles for doctors and other health professionals.