Vaccinations are a tricky business. Most cats are either over-vaccinated or under-vaccinated. Dex P. writes:
Rabies vaccinations are a matter of law in most states, so cats living in those states should follow the laws, whether they go outside or not. That said, there is no reason to vaccinate a cat with a modern three-year rabies vaccine more often than every three years. In most cases the three-year and one-year vaccines are identical, so the one-year vaccine is automatically overkill.
There are some cats who develop injection site sarcomas so the best protocol for vaccinating is to do the least that's necessary to remain effective. We recommend voicing your concerns to your veterinarian and developing a plan with them.
If you'd like to get "into the weeds" on this issue, there's a very good interview between Dr. Karen Becker and Dr. Ronald Schultz on the subject. Dr. Schultz is an expert in immunology and vaccinology at the School of Veterinary Medicine at the University of Wisconsin and he's come out in favor of fewer vaccinations. Links to the subsequent sections of the interview appear at the end of this video.
Dr. Becker is a favorite of ours and she has another good video on general vaccine advice here that we wholeheartedly agree with:
The bottom line is less is more. If possible, find a vet who will titer a pet instead of re-vaccinating automatically. This may require an additional form from your vet depending on the laws of your state, but we feel that it's worth the extra effort to avoid over-vaccinating.
We wish you and your kitties all the best, Dex!