A Queensland child has died with the flu, with the state's Chief Health Officer John Gerrard issuing an impassioned plea for people to get vaccinated.
The ABC understands the 11-year-old died last week in the Sunshine Coast University Hospital after contracting influenza.
It comes after a teenage girl died of influenza B on the New South Wales Central Coast.
Dr Gerrard said that this month 78 children aged six months to four years had been in hospital in Queensland with flu – 50 of them diagnosed with the B strain.
"Only one of these children was vaccinated," he said.
Another 11 babies aged under six months have also been admitted to hospital this month with the flu, eight of them with influenza B.
"Influenza B is causing severe illness in otherwise healthy Queenslanders, particularly in young people.
"We are concerned about the return of school that we may see transmission of influenza B in schools in the coming weeks," Dr Gerrard told the ABC.
"Influenza B is known to be associated with severe disease in children."
Dr Gerrard said he was also worried about pregnant women contracting the flu, given the risk they may lose their baby.
"This season we've had a number of pregnant women who've been on life support in intensive care and it's been quite striking how severe it's been this season so far," he said.
"Pregnant women are particularly prone to severe influenza because pregnancy is a state of relative immunosuppression.
"Influenza vaccine is very safe to give during pregnancy. We know that."
So far this year, Queensland has recorded 47,300 flu cases, including more than 3,800 people who required admission to hospital.
Dr Gerrard blamed the COVID-19 pandemic for this season's "pattern of virus disruption".
"There'll be children who have never been exposed to influenza B virus because of the events of the last three years," he said.
"It is particularly important for children and pregnant women to get the vaccine at present."
Sunshine Coast Health said clinicians were providing support to the family of the child who died.
"We would like to extend our sincere sympathies to the family during this extremely difficult time," a statement said.
"This experience is heartbreaking for everyone involved.
"Sunshine Coast Health protects the privacy and confidentiality of the patients who access our services and won't comment on the individual circumstances of care."