Seasonal flu shots have caused adverse reactions in 251 children under five in Western Australia, the state's chief health officer says.
Authorities last week suspended seasonal flu vaccinations for children under five across Australia, following a high level of bad reactions among children.
In Western Australia, 55 children suffered convulsions after having the vaccination, and almost 200 others suffered fevers and vomiting, chief health officer Dr Tarun Weeramanthri said.
One child is in a serious but stable condition at Princess Margaret Hospital.
Dr Weeramanthri said all states and territories were working to determine how many children had suffered adverse effects so that the national picture was clear.
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"Once that national picture is built up this week we'll know more about whether there is a problem, which areas it is in, what possible causes there are," he told the ABC on Tuesday.
He said it was likely that several batches would be linked to adverse reactions, given the scale of the immunisation program.
"We found no evidence of any single batch being the cause of these reactions," he said.
Queensland investigates child's death
Meanwhile, Queensland's health minister took early reports of a child's death, possibly from a flu vaccine, very seriously and ordered an immediate investigation, his office says.
A spokeswoman for Paul Lucas said the minister heard scant details about the case on April 9 and immediately ordered Queensland Health to look into the circumstances of the death.
Two-year-old Ashley Epapara was found dead in her cot on April 9, a day after she and her twin sister received the seasonal flu vaccine.
The Queensland Coroner is investigating the cause of her death.
The minister's spokeswoman said Mr Lucas contacted Queensland's chief health officer Jeannette Young on April 9, after sketchy details of the case surfaced.
She said Dr Young made contact with the Therapeutic Goods Administration, which had no notification of any vaccine-related death.
At that stage not even the child's name was known, the spokeswoman said. "He took it very seriously.
As soon as the minister was made aware of the issue he reported directly back to Queensland Health and asked them to start an urgent investigation," she said on Tuesday, adding the case was now a matter for the coroner.
"We need to wait for the results of the coroner's investigation. He will confirm yes or no whether it was the vaccine."
On Monday, Dr Young said Queensland Health was working closely with the coroner to determine the circumstances of the girl's death.
