My vet for 21 years, who has given me lots of free advice and a discount because he knows I rescue, has switched to an annual vaccine that they consider safer and far less likely to cause an adverse reaction. Having spoken to both the vets and the techs about the new vaccine, I do believe they are using it because they feel it is better for the animal. If your cat received the annual vaccine, I would feel far less concerned than if she was given the 3-year type. If it was the 3-year type, I'd follow up.