Vaccination against feline viral rhinotracheitis (also known as feline herpes virus), calici virus, and panleukopenia protects your cat from the top two upper respiratory viruses, and a virus that can destroy a cat’s immune system as well as cause permanent damage to the cerebellum in a kitten. FVRCP is considered a core vaccine, and ideally should be administered to kittens at six to eight weeks of age, then repeated every four weeks up to sixteen weeks of age, then boostered at 16 months, and given every year after that (there are 3-year injectable vaccines, but we don't recommend them.) The controversy over vaccine-associated sarcomas (VAS) in cats has been linked to adjuvanted vaccines, so I resource only non-adjuvanted intranasal vaccines for my patients.
It has recently come to my attention that there were several studies done in the early 2000's demonstrating a possible link between Injectable (also know as parenteral) FVRCP vaccination and Chronic Kidney Disease. The reason is that feline kidney cells are used to grow the material that FVRCP vaccine is made of, and those kidney cells cannot be completely filtered out of the vaccine. So when a cat gets vaccinated, they will not only produce antibodies to the three target viruses, they will also produce antibodies to their own kidney cells. A second study showed that actual kidney damage could be induced, even in very young cats, with the administration of repeated vaccinations. Now if you are reading this and are feeling a swell of anger growing deep within you, multiply that times a million and you'll understand how I felt as I read through each study publication (links below.)
The bright spot in all this is that these studies also showed that administration of intranasal vaccine did not cause the cats to produce the anti-kidney antibodies. I had stopped using injectable FVRCP before learning this information, because it seemed dumb to risk a vaccine-associated sarcoma when intranasal vaccine would avoid it. So imagine my glee to learn that choice was also protecting my patients from vaccine-associated kidney disease!
Now why in hell are vets still giving cats injectable FVRCP vaccine? The reason is "evidence based medicine!" The studies that have shown this possible link between vaccines and Chronic Kidney Disease were too small, didn't test enough cats, and weren't long enough ( cats were only followed for about a year.) And follow-up studies to firm up these suspicions are lacking (why aren't the Feline Practitioners and the endowed research funding groups clamoring for more information on this?) But as a cat owner, and veterinarian committed to not harming my patients, it's enough "proof" for me to decide I will never again administer an injectable FVRCP vaccine - not to my patients, not to my own cats... NEVER!
If you want to read more on this, here are some useful links: