A high school in Sydney's north-west has closed for the rest of the week after reporting one third of its staff had tested positive to COVID-19.
Tangara School for Girls, in Cherrybrook, on Tuesday informed parents it made the "difficult decision" to move years 7 to 11 to remote learning until Friday or "until further notice".
In a letter shared with Nine Radio, the school stated only one student case was currently known but this measure would "avoid the risk of further transmission".
The rest of the school remains open, including admin and primary classes, it says.
"Over the weekend one-third of our secondary staff have tested positive to COVID-19 placing pressure on teaching, supervision and operational needs at our school," the letter states.
It goes on to say one secondary student had tested positive, and encourage parents to test their children if they develop symptoms.
Tangara said it received "prudent" advice from NSW Health and the Association of Independent Schools before the decision was made.
"We also want to assure you that these decisions are never made lightly," the letter says.
Experts have warned a "new wave" of COVID-19 was currently spreading through Australia, as case numbers in NSW spiked last week.
There were 12,450 new infections reported in the seven days to Friday, with 809 people in hospital, according to NSW Health.
That's an increase of more than 2,400 cases on the figure from the week ending October 27.
Catherine Bennett, chair of epidemiology at Deakin University, said the next wave was starting across the country.
She expected case numbers were being underestimated as many infections were asymptomatic.
"We could see this and maybe another wave early next year. It just means there's that constant exposure risks going ahead," Professor Bennett said.
NSW Chief Health Officer Kerry Chant said the state was seeing the new Omircon sub-variants XBB, BQ 1.1 and B2 among the new cases.
"By looking at all the local information we have and what’s happening overseas, we believe COVID cases will rise in the coming weeks," she said.