William is almost 13, and hasn't had a vaccination of any sort since he was 6.
Two reasons for that:
Leptospirosis vaccination - he used to have that every year but had a relatively mild, but worrying, reaction to it when he was 6. I discussed it with the senior vet at the practice and he said if it had happened to his dog he wouldn't have him vaccinated against Leptospirosis again in case he had a worse, perhaps fatal, reaction. He said he might not think that way if we were in an area that had a lot of Leptospirosis cases, but he only very rarely saw a case in the practice despite there being a lot of unvaccinated dogs around.
Parvovirus, Distemper and Adenovirus vaccination - when William was young he was vaccinated annually because that's what the vaccination manufacturers and vets recommended. Then the guidelines issued by the WSAVA (World Small Animal Veterinary Association) recommended a booster every 3 years because it was recognised that the vaccination lasted for many years, perhaps for life. The guidelines changed again a few years ago and the WSAVA now recommends titre testing in preference to a booster every 3 years. William and my younger dog Louis were titre tested in 2013, which was more than 3 years after their previous boosters and both had immunity. Late in 2016 I had Louis tested again, but not William, then 12 years 6 months, because that same vet, plus the one I regularly see, plus the vet who does William's acupuncture, all prefer not to vaccinate old dogs, so I decided not to have him titre tested.
William won't be vaccinated again. Louis will probably be titre tested in 3 years time when he'll be 10.