FIV Vaccines – Just Say NO!

Your vet offers to vaccinate your cat for FIV. You think “well, sure, why not? Vaccines are great!” NO! Your cat should NEVER be vaccinated for FIV!

First, let me make myself clear – I love vaccines. Vaccines are wonderful things that prevent a number of very serious illnesses, and they are essential in eradicating deadly diseases. However, there are several excellent reasons why your cat should never receive the FIV vaccine (and the AAFP – American Association of Feline Practitioners – agrees):

1. Current tests for FIV cannot distinguish between a cat vaccinated for FIV and one infected with FIV. Once vaccinated, your cat will test positive for FIV for the rest of their lives.

2. We’re not sure exactly how effective the FIV vaccine is anyway. The manufacturer claims it’s abut 80% effective, but other studies have found it’s only about 50% effective at preventing FIV infection.

3. Indoor cats that have been spayed or neutered have almost no chance of contracting FIV anyway. FIV is most commonly spread through very deep bite wounds (like the kind seen between unneutered stray male cats).

OK, that’s all well and good, but so what? My vet and I would know that my cat was vaccinated for FIV. What’s the worst that could happen?

Imagine if your cat slipped out the door and got lost. She’s picked up and taken to the local county shelter, where she tests positive for FIV. Ideally, she is reunited with you, but realistically, most owners are never found. If she’s lucky, a rescue group like Calvin’s Paws will be able to take her in and put her up for adoption. Since we wouldn’t know her history, we would have to list her as FIV positive, and it would likely take a long time to get her adopted. If she’s unlucky, she would be euthanized at the shelter upon testing positive. This is the unfortunate fate that awaits most FIV+ cats that find themselves at a shelter.

The possible consequences of vaccinating your cat against FIV far outweighs the actual risk of your cat contracting and becoming ill with FIV. If a test that can differentiate between an FIV-infected cat and an FIV-vaccinated cat ever becomes available, then maybe the FIV vaccination recommendation would change. Until then, JUST SAY NO!

Click here to read the 2013 AAFP Vaccination Guidelines:

Mikael is proof that you can  live a happy, active life with FIV
   Mikael is proof that you can live a happy, active life with FIV
Madre has FIV and is living a very happy, very active life
Madre has FIV and is living a very happy, very active life

Calvin’s Paws is a 501(c)(3) rescue. We work through a network of foster homes throughout the Triangle area to save homeless cats and dogs. We are a dedicated group of volunteers with common goals: rescuing animals (both positives and non-infected felines), finding the best fitting homes for each animal, and educating the public on animal health and responsible pet ownership.

FIV Vaccines – Just Say NO!

10 thoughts on “FIV Vaccines – Just Say NO!

  1. Rita says:

    I don’t get your logic, you are against FIV vacine but pro-FELV when any cat who have been vaccinated will test positive. The reasons who claim against FIV could be exactly the same for the Felv vacine. I can see no sense.


    1. I’m glad you asked this, because this is actually a common misconception. The issue is that the tests for FIV and FeLV are fundamentally different (even when you use a combo test like a SNAP test). The test for FIV looks for antibodies (the body’s immune response) to the virus, while the test for FeLV looks for antigens (proteins on the surface of the virus itself). When you receive a vaccine, your body produces antibodies in response, just like you would if you were actually exposed to the disease. So with the FIV test, if a cat has been vaccinated, those antibodies that were produced in response to the vaccine will trigger a false positive on the FIV test. When you vaccinate a cat for FeLV, yes, antibodies are produced, but that’s not what the test for FeLV looks for, and so will it will NOT trigger a false positive.


    1. It seems so easy, but you’d be surprised at how many people either don’t microchip their cats or never register it or update their info. It always amazes us, but we get several calls each year when one of our adopted cats gets found lost and the owner never added their info to the chip. Luckily for our cats, we stay registered on all of their chips as the purchaser.


  2. okay if not a chip then a tatoo. there’s a solution around this that doesn’t mean just leave them to catch it and suffer. I took a stray to the vet today and he is positive. now I’ve got to catch his friends to see if they are. If there were a vaccine available, perhaps they would have a chance at not having it. Heck, he probably wouldn’t be positive because he was vetted and neutered at some point.


    1. The problem is that there is no test that can tell the difference between a cat infected with FIV and a cat that has been vaccinated for FIV. So even if he had been vaccinated against it when he was neutered, he would still be testing positive now. For all we can tell, that could in fact be the case now. Microchipping or tattooing is a great idea in theory, but in practice, both of those things would have to actually link to the cat’s medical records to be useful. Tattoos are great for showing a cat has been altered, but provides no other details. Microchips are useful if they are registered and kept up to date, but sadly that is often not the case. On the other hand, the vaccine actually offers very little protection against the virus (much like HIV vaccines in development for humans offer some protection, but not a lot), and the risk of the cat getting lost and testing a false positive later is much greater than the protection offered. Just last week, in a feral colony we had been working with, the caretaker trapped a cat and took it to a different vet. The cat tested positive for FIV on one test, and the vet immediately euthanized the cat. FIV cats have been shown to usually live healthy, normal lives, so even with a diagnosis of FIV, the cat usually has a great prognosis. None of the other cats in the colony were positive. So for us in the work we do every day and with what we’ve seen, the risks greatly outweigh the benefits of vaccinating. If and when new tests or more effective vaccines are available, that position could change, but for now, it’s just not worth it. As a side note – FeLV is a different disease and different story, and we absolutely recommend vaccinating against FeLV, and all cats in our program are vaccinated.


  3. Chiara says:

    Hello, I have neutered a feral (was supposed to be a TNR) (well, it seems like he was dumped, because he is very docile) and decided to test him before release. He is FIV +. I have 7 cats my own (all FIV-) and I was suggested not to release him because in his condition he will be better off indoor and he may still transmit the virus to other cats outside (even if he will be getting in less and less fights now). The main reason I would not take him out of my house is that he is too domestic and he is affectionate with me, it would feel like kicking out of the house one of my cats. Here comes the question: I am obviously concerned about my cats if I let him share the house with them, my “alfa” female would not let him become the boss and he is used to be the “alfa” out there so I am concerned those 2 will get into some serious fights also after giving the time to get used to each other. I would keep him if it wasn’t for his FIV status. Can anybody suggest a rescue that takes FIV +, or other FIV+ cats owner who would consider taking him? I am looking also for a new foster, I really can’t keep him long, with all my many cats, he is living in one bathroom. Or would vaccinating the other ones be worth in this case?


  4. djefneovndi says:

    This post is a bit old, but I am interested, so I will add my own two cents.
    I take your point about positive test cats entering the shelter, but don’t see the need to throw the baby (vaccine) out with the bathwater (test). Vets have come up with ways of marking spayed cats with a small scar or tattoo. Something similar could easily be developed for this vaccine. I also think your argument would benefit from some actual statistics about cats entering the shelter system who face euthanization, because right now you can’t prove that blocking this vaccine isn’t actually doing more harm than good. From an owner’s perspective, protecting your cat seems like a good thing.


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