FIV ' Feline Aids' FAQ

Questions and Answers on the newly released FIV (Feline Immunodeficiency Virus) vaccine. Commonly also called “Cat Aids”,

Q.- Are there any other FIV vaccines available?

A. - The only commercially available FIV vaccine is manufactured by Fort Dodge in the USA. Currently other companies, including one NZ consortium, are working on producing FIV vaccines, but the Fort Dodge one has been the only one commercially available in the USA for approximately 1 year.


Q.- Will the vaccine produce immunity in NZ cats?

A.- There are 5 different FIV sub-types ( or clades) – A,B,C,D & E. From the little amount of research done here it would appear that subtypes A and C are the most prevalent ones in NZ. The vaccine is composed of A & D fractions, and relies on “cross-immunity “to the other sub-types because there is a “conserved” part of the virus that is 85% similar in all the subtypes. A challenge model to demonstrate vaccine protection against subtype B has proved very effective. To date a challenge model to demonstrate protection against subtypes C and D has not yet been developed.


Q.- Will an adult cat have to be blood tested for FIV prior to being vaccinated?

A.- All adult cats (>4 months of age) will need to be blood tested prior to vaccination as otherwise the immune response mounted after vaccination will interfere with any current Elisa in-clinic tests available.
In the future, better testing methods will be able to differentiate between the vaccination antibody titre and a disease antibody titre. It is likely that these tests will use the polymerase chain reaction (PCR) test. This will give a positive result for FIV infection when FIV provirus is formed during the replication process in the host’s cells. The FIV vaccine does not replicate in the host’s cells, as it is a killed vaccine. Thus, a vaccinated cat, unless it is also infected with the live virus, will always test negative to a PCR test.


Q.- When is the best time to vaccinate ?

A.- Only normal, healthy cats should be vaccinated. Start vaccinations at 8 weeks of age and a series of 3 vaccinations are required for protective immunity. These need to be at 2-4 week intervals. This means that vets can choose to either vaccinate at 8,10 and 12 weeks; or 8, 12 and 16 weeks of age, when giving other core vaccinations. Annual boosters will be required.


Q.- Is the vaccine safe ?

A.- The vaccine is a killed vaccine and so cannot replicate and produce disease in a normal, healthy cat.



Q.- Why is there not a vaccine against the Human virus – HIV -1?

A.- There is more variation and there are more subtypes in the human form of the virus and therefore it is more difficult to develop a suitable vaccine. The feline virus is also a more stable form and doesn’t appear to mutate so readily. Vets have also been using another inactivated retroviral vaccine- against Feline Leukaemia -for some years, with a high level of acceptance.


Q.- Are there any side effects after vaccination?

A.- Some cats will be “unwell” for a period of 24-48 hours after vaccination. Symptoms may include pain and/or swelling at the vaccination site, inappetance, transient fever, depression and/or stiffness. This is a similar to some other vaccine reactions.


Q.- How common is FIV in NZ?

A.- It is reported that 14-29% of NZ cats test positive to FIV. Research data in 1989 (Swinney et al) gave the prevalence in “sick cats” at 27.3%; In all cats it was 14%. More recent, published data is not currently available.