You don't need to have any vaccinations for Australia. The recommended vaccinatinos for china are
(diphtheria), hepatitis A, (hepatitis B), (Japanese B encephalitis), (malaria), (polio), (TB), tetanus, typhoid.
the ones in brackets only if you fall into a particular high risk group (usualy health workers)
BUT if you are remaining within the airport then I'm sure you won't need to have any vaccinations at all.
I can't find any information to back this up though. Why not ask your GP or surgery nurse they'll be able to help.