The FIV Vaccine: What You Need to Know
(This post is Part 2 of our FIV series. If you missed Part 1, The Ins & Outs of FIV, we recommend that you read that post first, as it will give you a better understanding of what FIV is.)
The topic of vaccinations is a controversial one these days – to vaccinate or not to vaccinate? There are so many arguments for and against, it is difficult to know what the best option is. As with just about everything, the option that is best for one may not be the best for another. It is important to be as informed as possible, and, with the help of a veterinarian, make the decision that is best for you and your cat. The case is no different with the FIV vaccine.
The FIV vaccine was developed in 2002. It was at first praised as being 85% effective against FIV infection, but as more information about the vaccine came out, enthusiasm for it began to dwindle. There are a few issues with the vaccine that lead many to agree that it is not a suitable preventative option. In fact, there are veterinarians who will not even administer the vaccine.
Issue #1: A vaccinated cat will forever test positive for the virus.
Once a cat has been vaccinated against FIV, they will test positive for the virus for the rest of their life. There is no test that can determine if a cat is testing positive because they truly have the virus or because they have been vaccinated. This causes two very big problems:
- If a vaccinated cat gets lost and is then picked up by animal control or a kill-shelter, that cat will most likely get euthanized for testing positive for FIV, even though the cat is not truly infected.
- If an FIV+ cat is living with an FIV- cat and the FIV- cat has been vaccinated, there is no way to tell if the FIV- cat ever contracts the disease.
Issue #2: The FIV vaccine was only tested against one strain of the virus.
FIV has five known strains, or Clades – A, B, C, D, and E. The vaccine was developed using Clades A and D, but was only tested against Clade A. In the U.S., Clades A and B are the most common – Clade A being the most common in the western side of the country, and Clade B being the most common in the eastern side. Seeing as Clade B is one of the most common strains in the country, and the vaccine was not developed from nor tested against this strain, it unclear how effective the vaccine really is. While the vaccine may supposedly be 85% effective against FIV infection, that is only in regards to one strain of the virus.
Issue #3: The FIV vaccine is adjuvanted.
An adjuvanted vaccine is one that is made from a killed version of the virus with an added adjuvant, or agent that will help to stimulate the immune response of the cat to produce antibodies. The problem with adjuvanted vaccines is that they are suspect in the increase of Vaccine-Associated-Sarcomas (or VAS). Although VAS tumors are very rare (1 in 1,000), they are very aggressive. Even if they are surgically removed, they have a tendency to return even more aggressively than before.
The FIV vaccine is not just one shot – it is a series of three injections, given 2-4 weeks apart. Then, a booster is needed yearly. With so many injections needed, the risk of a VAS tumor developing at the injection site increases. If developed, these types of tumors are more deadly that FIV, so many believe that the vaccine is not worth the risk – the chances of contracting FIV are rare, and even if contracted, a cat can live a long and healthy life with the virus.
As stated previously, the decision that is right for one may not be right for another. The FIV vaccine may be a suitable option for some. It is important to explore all options and discuss them with your veterinarian before making a decision.
Have you had to make the decision of whether or not to vaccinate your cat against FIV? We would love to hear about your decision and the reasons you made it.