Queensland schools are being encouraged to reinstate mask-wearing after the revelation that one in 50 of the state's students have tested positive for COVID-19.
The government, meanwhile, has come under fire for failing to adequately audit ventilation in schools.
Chief Health Officer John Gerrard said authorities would not "specifically" mandate masks in schools, but encouraged principals to reintroduce them if required during "significant outbreaks".
"It all depends on the individual schools, the individual staff — the leadership of the schools can make those decisions themselves," he said.
Last week 14,000 COVID-19 cases were reported in schools — a 55 per cent increase on 9,000 the week before.
This week a further 15,338 cases were reported among children aged five to 11, according to Queensland Health data obtained by the ABC.
Five audits in Brisbane
Ventilation audits began at Graceville State School, McGregor State High School, Albany Creek State High School, Narbethong Special School and Sherwood State School in February this year, Education Minister Grace Grace's response to a question on notice said.
"The initial draft results generally indicate that the carbon dioxide (CO2) levels in the majority of classrooms were at acceptable levels," the Minister's statement said.
"For the small number of classrooms that had slightly elevated CO2 levels, cross ventilation through open airways (windows and doors) on at least two opposing sides of the room would provide adequate ventilation."
The expenditure on ventilation efforts has totalled more than $894,000, including almost $24,000 spent on audits, almost $433,000 on 1,420 carbon dioxide monitors and a little less than $438,000 on 250 air purifiers.
'Extraordinary failure'
Air quality expert Lidia Morawska said the number of schools audited was "grossly inadequate".
"This is such a priority, and this was expected — once the kids are back and there are no masks in schools and there is no ventilation, then COVID would be spreading in schools," she said.
"We knew this was going to happen since the end of last year, but we've been talking about this for the last two years, so what can we say?
"They really need to find out a way of doing [ventilation audits] much, much faster."
LNP education spokesperson Christian Rowan said the state government had failed to adequately plan for sufficient ventilation in schools.
"To learn the Labor state government in Queensland has only assessed five schools to improve ventilation is an extraordinary failure," he said.
An education department spokesperson said further ventilation audits had been requested and would be completed "in due course, following delays as a result of recent flooding disruptions".
Ms Grace said the department followed expert health advice and that in most cases natural ventilation and air conditioning and fresh air from outside was sufficient.
"However, CO2 monitors are available to schools on request, audits can be carried out, and air purifiers are provided where required," she said.
'Didn't see the spike'
Infectious disease expert Paul Griffin said ventilation played an important role in preventing the spread of COVID-19.
"It's not going to take us back to zero, but as a comprehensive package we certainly do need to include a focus on ventilation again," he said.
"There needs to be an ongoing focus on ventilation until we basically get this current situation under control, really, so they absolutely need to keep that work up."
Dr Griffin said there were a multitude of factors contributing to the wave of the COVID-19 sub-variant BA.2.
He said the spread among students was being driven by the slightly more infectious nature of BA.2, the low vaccination rates among children, and because children were not the best at social distancing, hand hygiene or wearing masks.
"Then I think the environment is conducive … with maybe not having addressed ventilation, but also having a lot of them in classrooms, they interact in different classes," Dr Griffin said.
"I think for the first few weeks we switched off a few of the extracurricular activities and other things, so perhaps we didn't see the spike that was inevitable when kids went back to school and that was delayed when we resumed sport and camps.
Back-to-school blitz
To improve lagging vaccination rates among children, Health Minister Yvette D'ath announced vaccination clinics would be open over school holidays.
She also said there would be a vaccination blitz at school clinic when the term resumed after the holidays.
"We do need to lift the vaccination rates of our young children — we want to make it as available as we can to parents," she said.
"But can I say to parents, don't wait until the start of next school term — if you can, please take your child to get vaccinated over the school holidays."
