Thats news to me. I vaccinate my animals every year. Two of my vets don't think a three year gap is fine, they send reminders warning of the perils of missed vaccinations, and having to start again with the 1st Jab and the 2nd a month later etc. Due to family ill health a cat missed its jabs by a month and ended up with cat-flu, so after it suffered intensive care, force feeding it etc, I wouldn't risk missing their jabs again. Thanks.