Deputy Chief Medical Officer Paul Kelly insists while the rate of new coronavirus cases is slowing, Australia is "definitely not" through the health crisis.
There are now 5544 cases of COVID-19 across the country, with the death toll rising to 30 after a woman in her 70s died in Victoria, and the death of a man in his 80s at Canberra Hospital.
Professor Kelly said the daily rate of case increases is less than they were a week ago and reflect measures taken to stop the spread of the virus, such as social distancing.
But he told people not to get carried away by these successes.
"I really would caution against thinking we have got through this completely, because we definitely have not, " Prof Kelly told reporters in Canberra on Saturday.
He again stressed there was no need for people to wear masks in public, partly because of the the constraint on supply, but also because if worn incorrectly they can be "quiet dangerous".
The warning came as federal Health Minister Greg Hunt said the government is providing $220 million to upgrade a CSIRO biosecurity research facility in Geelong to assist testing for a potential COVID-19 vaccine.
"The world-leading team of scientists in Geelong has already commenced pre-clinical trials for vaccine candidates and I am confident they are moving ever closer to bringing forward a vaccine for COVID-19," Mr Hunt said in a statement.
In NSW, state Health Minister Brad Hazzard again defended the government's handling of the Ruby Princess cruise liner, which allowed more than 2000 travellers to disembark in Sydney, many of which are thought to have assisted the spread of COVID-19.
"Can I just say that the experts who made the decision were the best in the world," Mr Hazzard told reporters in Sydney.
"And the appropriate thing at this point is for the investigation to continue," he added, in reference to a probe into the incident by NSW Police Commissioner Mick Fuller.
In Queensland, five men have been charged for non-essential travel to a remote community in the north of the state.
"It is extraordinarily disappointing," Police Commissioner Katarina Carroll said.
"We are doing this for our safety and the safety of our community. I just ask that we all work together."
It comes as some Victorians continue to flout coronavirus restrictions with police slapping 25 more people with fines.
Meanwhile, there was good news for farmers after the Morrison government announced a temporary relaxation of backpacker visa rules to enable them to pick crops and work in regional communities until the virus passes.
"This is a critical time for our food security in our nation, but also continuing to keep our export markets open," Agriculture Minister David Littleproud told reporters in Brisbane.
The visa changes will allow working holiday makers to continue to work in agriculture and food processing and are also geared to other key industries, such as health and aged and disability care.
Working holiday makers who are working in these critical sectors will be exempt from the six-month work limitation with one employer, and eligible for a further visa to keep working if their current visa is due to expire in the next six months.
Opposition health spokesman Chris Bowen believes the government has struck the "right balance".
"There is still fruit to be picked. There's still other jobs in regional Australia to be done," Mr Bowen told reporters in Sydney.