New South Wales school students should return to the classroom for Term Four, an infectious diseases expert said.
Professor Robert Booy told Today that on-site schooling was important for young people's mental health and it should resume by early October for the start of Term Four.
"School is so necessary for families and teachers … for students for their education, socialisation and mental health and exercise," Professor Booy said.
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"Schools need to go back when it is safe and that won't be too long. Term Four is certainly on the cards."
Professor Booy, of the University of Sydney, also said expanding COVID-19 vaccinations for people aged 16 to 39 should make 'a world of difference' to stemming the Delta outbreak.
"If we can get them vaccinated rapidly it will make a real dent to the numbers and transmission and get this under control."
Professor Booy said Greater Sydney is "winning pandemic battles but still losing the war", despite encouraging results from the lockdown.
"The lockdown measures are working region by region, district by district. Cases in the Eastern Suburbs, Fairfield, they are going down and they have been for a while. So it is not as if there isn't successes along the way.
"The skirmishes are being won (but) the overall war we are still losing. We do it LGA by LGA."
Professor Booy also suggested state and federal politicians should adopt a united front in efforts to combat the pandemic.
"Hearing the politicians speak on both sides, why don't they get together … and stop sniping at each and work together properly."
Meanwhile, Treasurer Josh Frydenberg said Australians will have to learn to live with COVID-19 – even it means people continue to die from the pandemic.
"We are going to have to learn to live with COVID. We have to accept there are going to be deaths," he said.
"We are going to have to accept there is going to be hospitalisations but when we get to those (vaccination) targets we can start to open up the economy."
Mr Frydenberg also flagged federal government economic support would drop when states hit vaccination targets.
"The government's emergency economic support does not continue indefinitely. It is there until we get the vaccination rate to the levels that they agreed with the Prime Minister at National Cabinet."