What I am wondering is, are yearly boosters for older cats really necessary? Do cats tend to have immunity once they have had lots of previous boosters? (don't actually know what they are vaccinated against either) The vets seem to think yearly boosters are essential regardless of how many times the cat has been vaccinated before but I wonder if anyone knows much about this?

We have always had cats that have the initial vaccinations but never the yearly boosters. OUr cats havent suffered any ill health or done worse than cats that do have regular boosters.

I used to get my lot done yearly, but then left it when they got to about 4 - anyway, last year I had two that had not been vaccinated for at least 3 years, and another younger cat who had been vaccinated 6 months before - all 3 got cat flu the same, and the one that was vaccinated wasn't any better or any worse than the other two!