Wanniassa School's junior campus and Ainslie School had positive cases on site last week, forcing between 60 and 70 people at each school to go into quarantine.

Dr Vanessa Johnston said evidence had emerged that a standard, thorough clean of high-touch surfaces was enough to make areas of a school safe in the event of a confirmed case.

But schools are still likely to close to allow time for contact tracing if there is a case on campus.

"Often we get notification in these cases quite late in the day. It takes some time to do the contact tracing," Dr Johnston said.

"And so really, it's sort of by necessity that the school might need to close by a day not even just for the cleaning, but just to make sure that we can work through really closely the contact tracing."

Dr Johnston said ACT Health was trying to reduce the impact of any potential COVID-19 cases at schools.

"We've talked about all of the measures that we're doing in schools to reduce mixing and mingling, so cohorting of classes and staggered start times and break times.

"But additionally, once we identify a case and the contacts around them their vaccination status becomes pretty critical in determining whether they isolate or quarantine for seven days or 14 days."

Unvaccinated primary school children will still have to quarantine for 14 days if they are a close contact of a case, however vaccinated high school and college students and teachers would only need to quarantine for seven days.

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Dr Johnston couldn't say whether close contacts would be confined to the class where the positive case spent their time as there was differences between early childhood, primary school, high school and college settings.

"It's a very nuanced, risk-based assessment so we can really minimise the number of people who have to lose out."

No further cases of COVID-19 in Canberra schools had been detected on Tuesday. Wanniassa School was closed on Monday for contact tracing but reopened on Tuesday.

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