Two year-old Ashlee Epapara was found dead in her cot on April 9, the morning after she and her twin sister received the seasonal flu vaccination from their family GP in Brisbane.

The bereaved father, David Epapara said he could not believe this was coincidental.

Mr Epapara said both children had been perfectly fine until they were inoculated with the combined jab for seasonal flu and swine flu.

We don't know much about what happened at this stage, said Mr Epapara from the family's Mount Gravatt home at the south side of Brisbane.

But it seems too much of a coincidence for a healthy girl, after having this vaccine, to just pass away. It is shocking.

Nearly 60 young children and babies primarily in Western Australia have experienced fever, fits and vomiting after being inoculated with the new seasonal flu vaccine, prompting Australia's chief medical officer to declare for a halt on flu vaccination for children under five.

In Perth, the condition of a seriously-ill one year-old girl who was listed by the Princess Margaret Hospital as critical last week, has improved yesterday.

Jeannette Young, chief health officer of Queensland said there was no proof that the seasonal vaccine was to blame for baby Ashley's death.

Until now, neither Queensland Health nor the relevant national body had been advised of, or were aware of, any death allegedly related to a 2010 seasonal flu vaccination in Queensland, said Dr Young.

Queensland Health is working closely with the Coroner on this matter. Our deepest sympathies go out to the family at this time.