We were hit very badly when we introduced two immunised hybrids to our flock of pedigrees. I use the term 'immunised' because they are no longer 'vaccinated', which is to be given a dead virus. They do vaccinate here, but only against Newcastle Disease for show birds and it has to be done annually. Our problems arose due to the stress induced in the move, which caused the live viruses to flare up and be infectious. The live viruses given are the mildest in each group and in our case there were three of them. Now they have added a fourth- Mycoplasma. These viruses are introduced gradually, either by spraying the air in the coop or in the water. Catching all three at the same time left us with a very sick flock and a £200 vet bill.
I don't see the need for immunisation, unless the birds are kept in extremely poor conditions which promote disease. They don't immunise here and they don't beak clip either- both are unnecessary because the welfare standards are so high.
I've now read of numerous cases where immunised birds have been bought, become stressed, the four viruses have flared up and they have died.
Two things spring to mind Ghdp. Firstly, these problems only seem to occur when immunised birds are moved to non-immunised, so buying in your bantams should be fine. Secondly, £30 a hen, unless it is a top quality pedigree breed is a ridiculous price- healthy pol hybrids here are €12 each and we bought our last lot for €5 each.