The Chief Medical Officer Brendan Murphy has defended advice he provided to the federal cabinet after Home Affairs Minister Peter Dutton became one of the now more than 200 Australians to become infected.
Professor Murphy did not press the cabinet to be tested for Covid-19 despite the high profile diagnosis.
Mr Dutton became sick with coronavirus on Friday, just days after attending a cabinet meeting that included Prime Minister Scott Morrison on Tuesday.
Professor Murphy says it has always been public advice that people only be tested after being in contact with someone infected with coronavirus within 24 hours of them developing symptoms.
"If you have been in contact with them two or three days before they are symptomatic, they are very, very, very unlikely to be infectious," he told reporters in Melbourne on Saturday.
Australia's Chief Medical Officer Professor Brendan Murphy. Source: AAP
Labor health spokesman Chris Bowen questioned the "24-hour" advice when people were being told to self-isolate should they have come in contact with someone who contracted the virus.
"Now there is a lack of information before the Australian people, and this confusion makes it worse," Mr Bowen told reporters in Sydney.
Labor's education spokeswoman Tanya Plibersek said she followed the medical advice to self-isolate and have the COVID-19 test after attending a university conference where a delegate may have had the virus two weeks ago.
"That's exactly what I did. The test was negative," she tweeted.
Australia clocked up 237 cases of COVID-19 on Saturday after three South Australians became infected. There are some 140,000 cases worldwide.
Of those reported cases in Australia, three people have died and 27 people are reported to have recovered.
SA Premier Stephen Marshall announced the additional cases ahead of a teleconference between Mr Morrison, the six premiers and two chief ministers - now know as the national cabinet - at midday on Sunday.
This follows Friday's Council of Australian Governments (COAG) meeting which took on the expert advice that all non-essential gatherings of more than 500 people should be cancelled from Monday.
"We all know this is a global epidemic which we will not be immune from here in Australia but, by working in advance, by working together, we can minimise the effects," Mr Marshall told reporters in Adelaide.
Events such as the Melbourne Grand Prix and Sydney's Easter Show have already been cancelled. In New Zealand, the commemoration of the Christchurch massacre a year ago has also been cancelled.
"We do know large gatherings, large groups are well known internationally to be one of the quickest ways to spread a virus if there is community transmission," Prof Murphy said.
The closing down of sporting events impacts not only on fans, but also small businesses involved.
"It's not to say these things shouldn't be cancelled, but we've got to understand the impact on small businesses and their staff is absolutely enormous, catastrophic," Australian Small Business and Family Enterprise Ombudsman Kate Carnell told ABC television.
She said while initiatives in the government's near-$18 billion stimulus package will help, the problem is businesses don't know how long this is going on for.
A face mask is seen discarded on the ground in Sydney. Source: AAP
The government has indicated there could be further measures in the May budget.
Ms Carnell said the 1.4 million small businesses that don't employ people need to be looked at.
"So far there is nothing for that group," she said.
