Kaz, very tricky situation. The recommendation this year is for under 5's not to get the fluvax. It is exactly the same formulation that caused problems last year. However doing a quick google I found the govt recommendations here: 2011 government seasonal influenza vaccine information: Immunisation - Victorian Government Health Information, Australia
It looks as if there are some alternative pediatric formulations available that can be used and this is what you need to discuss with your care providers.