Why Isn’t the Vaccine for FIV/Feline AIDS Widely Used?


Important Information For All Cat Owners. Dr. Barchas, DVM, Explains Why The Use Of This Vaccine Remains Controversial.

A comment on the recent post about a potential treatment for FIV/Feline AIDS caught my eye. Here is the comment.

S Bridges posted a comment on August 7th, 2008 at 4:02 pm

Is there any way to participate in the testing of a new FIV drug? We adopted a 3 year old cat a year ago and he, as of today, is positive for FIV. We were told that he may be showing a positive result from a previous FIV vaccination but we do not know if he has been vaccinated.

A vaccine for FIV (feline immunodeficiency virus) has been on the market for several years. It has been the subject of intense controversy among veterinarians since its introduction. The vaccine is not widely used.

Many experts question the effectiveness of the FIV vaccine. Laboratory studies performed by the vaccine’s manufacturer have shown efficacy of the vaccine against some strains of the virus. However, there is no conclusive proof that the vaccine works in real life. As well, there is an inherent conflict of interest in studies performed by the manufacturer.

Another major complaint about the vaccine is that it interferes with testing for FIV. The test for FIV checks for antibodies to the virus. Any cat that receives the vaccine will develop antibodies to FIV. Therefore, any cat that receives the vaccine will test positive for FIV–even if he is not infected.

Is the cat belonging to the comment’s author actually infected with FIV, or has he received the vaccine? Because the vaccine is not commonly used, it’s most likely that the cat is infected. However, there is no way to know for sure. And, sadly, clinical trials of the treatment mentioned in the original post are not yet under way.

This situation is unfortunate, but there is a silver lining. FIV is fatal, but the disease takes several years to run its course. I hope that a more advanced test, one that can differentiate infected cats from vaccinated cats, will be available soon.

In the meanwhile, my advice to the commenter is as follows. Enjoy your new cat, and let him live a normal life. Keep him inside to protect him from contagious disease, and to protect other cats from possible FIV infection. Get veterinary examinations at least twice each year. And keep your fingers crossed.

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