Tests later confirmed the mother-of-two died of pneumococcal meningitis.
The infection is covered by a vaccine that is on the National Immunisation Programme Schedule and is recommended to be given to babies at 2, 4 and 6 months.
There were 154 deaths from pneumococcal disease in 2004. It is passed on by touching infected people.
Since the introduction of the vaccination more than a decade ago, the numbers of pneumococcal deaths has reduced dramatically.
Husband John Petrak has opened up on the crushing loss and battle he faces as a solo father of two.
"Imogen's biggest dream was to see our daughter and she didn't get to do that. We knew we were having a girl and she was just aching to see her. She had all her dresses picked out," he told the Gold Coast Bulletin.
Petrak said he's dealing with a raft of bittersweet emotions after welcoming his daughter into the world just hours before his wife died.
"The only way I can explain it was feeling every emotion at the same time. Worry, sadness, happiness, joy - everything all at once."
A GoFundMe page set up by family friend Renee King to support the family has raised $118,000.