Dramatic changes have occurred in the past 10 years regarding the way veterinarians view vaccines and vaccination practices. The concepts of core and non-core vaccines, disease risk assessment, extended inter-vaccination intervals, and using products that minimize the risks of vaccine-associated sarcoma (VAS) are currently mainstream veterinary medicine. There are now a number of publications that document the long duration of immunity provided by most feline viral vaccines. The third revision of the American Association of Feline Practitioners (AAFP) Vaccination Guidelines for cats was published in late 2006. This very through document is exhaustively referenced and is an outstanding resource for veterinary practitioners as they change vaccination practices.

The AAFP vaccine guidelines specifically recommend avoiding vaccines that cause persistent local tissue inflammation and which might lead to VAS development. This means a general rule of avoiding adjuvanted vaccines and using non-adjuvanted vaccines whenever possible.

Core Vaccines for Cats

Modified live (MLV) FVRCP vaccines are recommended because they are not adjuvanted and do not carry the same risk of inducing chronic vaccine site inflammation that can produce VAS. In addition, a recent study has shown more rapid development of immunity against feline parvovirus in kittens given MLV FVRCP compared to those given killed FVRCP vaccine.

Feline leukemia virus (FeLV) vaccine is still on the AAFP non-core list but I consider it a core vaccine for pediatric patients with the caveat that a non-adjuvanted FeLV vaccine that does not carry the risk of post-vaccinal inflammation that could lead to VAS should be used. The reason for recommending universal kittenhood protection against FeLV is because cats under a year of age are at greatest risk for acquiring this disease. Virtually 100% of kittens infected with FeLV at 6 weeks of age or less will remain persistently infected for life. At 6 months of age, the risk of persistent infection drops to 30% and this decreases further to 5% or less after 12 months due to the development of natural resistance to this disease with age. When we ask clients about their kitten's environment, they may tell us that the kitten will be kept only indoors. However, the kitten may escape to the outside or the client may begin allowing the cat outside. The owner may not return the kitten for FeLV vaccination after the pediatric vaccination series has been completed even though the kitten's risk of exposure to FeLV has changed. By vaccinating the most susceptible individuals (young kittens) we will provide the best possible protection during the period of highest susceptibility to the disease. After a year of age, if the cat truly is kept only indoors without exposure to FeLV-infected cats, we do not need to continue FeLV vaccine administration.

What about virulent systemic calicivirus? See attached FAQ sheet about this virus.

I do not recommend giving Chlamydophila or Bordetella bacterins to household pet cats even though these vaccines remain on the AAFP non-core list. Both of these diseases are very uncommon causes of upper respiratory disease and these vaccines are reactive and have a short duration of immunity. Chlamydophila or Bordetella bacterins may be helpful for short-term use in shelter or cattery situations where an outbreak of upper respiratory disease has occurred if these agents are cultured from a number of cats and confirmed as a major component of the respiratory syndrome.

The feline infectious peritonitis (FIP coronavirus) vaccine and feline Giardia vaccines are on the AAFP not recommended list for reasons of lack of efficacy.

In my opinion, the currently available FIV vaccine is also not acceptable because of poor to minimal efficacy. This vaccine is adjuvanted which means that it carries the risk of VAS. FIV-vaccinated cats will also test falsely positive on antibody-based tests (ELISA, Western Blot, IFA) for at least a year post-vaccination. FIV PCR testing is not yet sufficiently accurate to help us differentiate vaccinated from naturally-infected cats.