Asymptomatic vs. presymptomatic - what's the difference?

In the early stages of infection, there is little difference between the two.

People who are asymptomatic do not show symptoms throughout the duration of their infection.

Those who are presymptomatic have the virus, but have yet to show any symptoms.

Dr Swan said anyone with symptoms, and close contacts of people with symptoms or who have tested positive, should get a test.

People do find it difficult to differentiate the message between asymptomatic, presymptomatic and symptomatic," he said.

"The clear story here is that if you've got symptoms, you need to be tested. Any symptom at all.

"If you're positive, obviously, you have to isolate for 14 days and if you're not positive, you can breathe a sigh of relief.

Deputy Chief Medical Officer Nick Coatsworth said earlier this month that asymptomatic and presymptomatic cases were the reason people needed to provide details of everyone they'd been in contact with in the days leading up to their positive Covid test.

"One of the challenges with COVID-19 is this asymptomatic period, and it's probably better characterised as a presymptomatic period, before which you would start to develop symptoms but you are nonetheless infectious," he said.

"That informs our national testing and contact tracing guidance, of course.

"The likelihood of people who are truly asymptomatic transmitting the disease is not known."

Dr Sacha Stelzer-Braid from UNSW's School of Medical Sciences said concerns around transmission from people who didn't have symptoms was part of the reason advice around face masks was changing in parts of Australia.

"As people infected with SARS-CoV-2 can transmit the virus while asymptomatic or presymptomatic, masks can prevent those people from transmitting the virus," she told the ABC.