Having years of direct interaction working in the vet field, some skepticism is warranted. Ignoring the lack of studies, I’ve had drug reps explain how the three year and one year rabies vaccines are actually the exact same shot made from the same batch. It just costs a good bit less to license some of it as one year. And they can technically charge a little more for it so buying it over three years is a greater gain than the single three-year shot.

Past that special bit of marketing, we’re also lacking in studies of dog/cat titers to have a good understanding of when/if booster shots are needed for animals. There’s a decent set of vets who believe it is a lot more like humans where it’s make it through the initial series and you’re good for life vs needing the yearly updates. Bordatella is likely the most abused booster with some boarding facilities requiring a booster every 6 months for animals while even the vets usually state yearly.

To be clear, vaccines are good and should be used. The unclear question is if they really need to be yearly for animals.