Australia's national science agency has joined the race to find a vaccine for the coronavirus, with testing on two potential candidates beginning in Victoria.

Australia's national science agency has begun testing potential coronavirus vaccines in what has been described as a critical milestone in the global fight against COVID-19.

CSIRO scientists are performing the first stage of testing for two vaccine candidates at the agency's high-containment biosecurity facility in Geelong.

The pre-clinical trials, which are expected to take three months, will use animal subjects to test whether the potential vaccines from the University of Oxford and Inovio Pharmaceuticals are safe and effective.

The trials come as Australia's COVID-19 cases reach 4860 and the death toll rises to 21, with Deputy Chief Medical Officer Paul Kelly on Wednesday warning the virus won't be beaten without a vaccine.

CSIRO chief executive Dr Larry Marshall has described the testing as a critical milestone while health and biosecurity director Dr Rob Grenfell says it is very significant given the race by staff to get ready.

"Usually it takes one to two years to do this and we have apparently done it in eight weeks, so that's actually really good," Dr Grenfell told AAP.

The vaccine candidates were identified for CSIRO's first trials by the Coalition for Epidemic Preparedness Innovations, in consultation with the World Health Organisation. They're the first of a number the CSIRO hopes to test.

Dr Grenfell understands that one of the vaccine candidates is also being tested overseas and if it is shown to be safe and effective in both trials, there would be a rapid conversion into human trials.

"These types of studies are vital to give us the confidence to move into human studies," he said.

Professor Trevor Drew, who leads CSIRO's coronavirus and vaccine work, said they had been studying SARS CoV-2, which causes COVID-19, since January.

"We are carefully balancing operating at speed with the critical need for safety in response to this global public health emergency," Professor Drew said in a statement.

Dr Grenfell feels very optimistic about the fight against COVID-19 but said a vaccine was still a ways off, with suggestions it could be 18 months.

"The scientific ingenuity that we're using, the global collaboration and co-operation is astounding," he said.

"We've seen some momentous science across many avenues of the vaccine development pathway globally, so yes, I'm optimistic.

"At the moment, the best thing that we can all do is to maintain our social distancing and self-quarantining to minimise the spread whilst we're waiting for effective drugs and vaccines."