On Saturday, there were 4110 new infections with NSW recording 2482 cases, the highest number for any state or territory since the start of the pandemic.
In NSW, a handful of positive cases at a Byron Bay caravan park meant dozens of guests - including schoolies - have had to isolate inside their caravans and cabins.
In Victoria, an outbreak at Camp Rumbug in South Gippsland that began last week has grown to about 50 cases across two Melbourne schools, with hundreds of people forced into isolation.
The outbreaks, coming a week before Christmas, have thrown travel plans into disarray.
Victoria added another 1504 cases on Saturday with numbers climbing quickly in recent days.
They are also rising in other parts of the country, with 73 new local cases in South Australia on Saturday, 31 in Queensland, 18 in the ACT and four in Tasmania.
Prime Minister Scott Morrison said people need to be careful not to cause alarm when discussing case numbers.
"We're past the time when we just talk about case numbers. It is a leading indicator on some issues, but the real issue is how many people are experiencing serious illness," he told reporters in Hobart on Saturday.
There are 384 patients in hospital in Victoria, and 206 in NSW.
Authorities maintain there will be enough vaccine to meet demand for booster shots, as well as jabs for children aged five to 11, which will become available from January.
More than one million Australians have received a third booster shot.
