What thread is that one? This is from the immunisation handbook I linked above.

(iii) Interchangeability of OPV and IPV: Oral poliomyelitis vaccine (OPV) is no longer in use in Australia. OPV and IPV are interchangeable. Children commenced on OPV should complete their polio vaccination schedule using IPV (IPOL) or IPV-containing vaccines.

From this page:

Immunise - 3.16 Poliomyelitis

It does say there is a seperate vaccine available, but it doesn't say if it is suitable for children less then eight years of age.