Rules for people inside enclosed spaces have become even stricter as the Federal Government tries to hamper the increase of Covid-19 cases.
Prime Minister Scott Morrison said all the decisions are being made for at least six months.
"But what we are now moving to is an arrangement for gatherings of less than 100, is that they would be four square metres provided per person in an enclosed space, in a room, so that’s two meters by two metres," he said.
"So for example, if you’ve got a room, if you’ve got a premises, if you’ve got a meeting room or something like that, that’s 100 square metres, then you can have 25 people in that room.
"Now, in addition to that, you should continue to practise wherever possible the 1m or 1.5m of healthy distance between each of us, to ensure that we are limiting the contact and limiting the potential for the spread of the virus."
Chief medical officer Brendan Murphy said there are still a lot of people who have been diagnosed with Covid-19 after time overseas.
"This is your civic duty to your fellow Australians to stay home for that entire 14 days, if you’ve come back to Australia," he said.
"No exceptions and if you see anyone who is not abiding by that ... make sure they do because we are really serious about that.
"It is such a big impact on our outbreaks in the last few days."
Dr Murphy also said people should be distancing yourself from every fellow Australian where possible.
"There’s no point having a gathering of 20 people if it’s in a tiny room and you’re all together," he said.
"Nobody should be going to work or mixing with society or friends, or going out if they are unwell at all.
"Stay at home if you’re unwell. Only go out when you’re feeling well. Go to work when you’re feeling well."
On whether or not schools should remain open, Dr Murphy said they do have some concerns that children may have a role in transmission but most children seemed to have got the virus adults.
We think keeping children at home when there is relatively no community spread is probably disproportionate given they probably won’t stay at home anyway," he said.
"They may be cared for by elderly parents. There may be circumstances where there are outbreaks in an area where we do need to close schools for a period of time.
"Our strategy for the next six months to keep schools open and we think that risk is appropriate."
Mr Morrison said states also agreed to work on identifying how relief can be provided for tenants in both commercial and residential areas, and ensuring that tenancy legislation is protecting those tenants over the next six months at least.
"That work will be done by states and territories, as it is a state and territory matter, and that work will be led by Western Australia, together with New South Wales, working with all the other states and territories, to bring back some model rules that can be applied in hardship cases," he said.
"So understanding what the trigger might be and how in those circumstances the tenants would be able to maintain their tenancies.
"Now I know that will mean something for landlords, just as the decision taken today means something for banks, just like the decisions we have already taken as a commonwealth government means things for our balance sheets, and as a people, for the commonwealth government, as it does for the states.
"It will also mean something for those who sadly might be stood down from their employment and have to look at their annual leave arrangements and sick leave arrangements."
The biosecurity act is being used to ban all non-essential travel into Indigenous communities.
Medical and health staff will be able to enter, as well as those providing mental health, police and educational services.
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