From RSPCA
http://kb.rspca.org.au/Why-cant-I-vaccinate-my-rabbit-against-Myxomatosis_260.html
Why can't I vaccinate my rabbit against Myxomatosis?
Myxoma virus is now widespread across the Australian environment which places domestic rabbits at risk of infection. There are two vaccinations against myxomatosis, but these are not permitted to be used in Australia.
The government argues that this is because the vaccines are ‘live-virus’ vaccinations, meaning they contain weakened forms of the virus; either the Shope’s fibroma virus or a cell-culture derived strain. Their concern regarding these vaccines is that the weakened viruses in the vaccine could spread from domestic rabbits to the pest rabbit population, immunising them against myxomatosis. Since the myxoma virus is still used to control wild rabbit populations in Australia (albeit to a lesser extent than other methods), the vaccine has not been approved for commercial use here until further research has shown that the risk of transmission of the weakened virus between animals doesn’t occur.
RSPCA Australia has repeatedly called for a review of available myxoma virus vaccines and a scientific assessment of their likely impacts in the Australian setting. We would like to see action taken to ensure that all domestic rabbits can be protected against contracting myxomatosis.
Further information is available at this link:
http://www.agriculture.gov.au/animal/health/myxomatosis-vaccine 
