Concerns About Vaccination

two cats restingVaccination has become much more of a contentious issue in recent years. People sometimes ask the questions: “Feline vaccines: are they safe?”  “Are there any problems associated with vaccination and should the need for vaccination be questioned?”

Are there side effects associated with vaccination?

Side effects associated with vaccination have been rare events in the past. More recently, short-term vaccine reactions have been recognised more frequently, possibly associated with new adjuvants (incorporated in vaccines to improve the immune response and subsequent protection) in some of the newer vaccines (such as feline leukaemia virus). These reactions are generally characterised by a short period of dullness and malaise, sometimes with an increased temperature, usually within 24-72 hours of vaccination. This will resolve spontaneously, usually within 24 hours.  Reaction may also occur at the site of vaccination taking the form of a small nodule. These too will usually resolve quickly, within a few days, but if the lump persists you should contact your veterinarian. A more serious, long-term, adverse reaction has been reported in the form of development of sarcomas (a type of tumour). This is a malignant tumour that can be difficult to cure. Studies are underway to establish just how significant the risk of this side effect is but the preliminary results from extensive studies in the USA suggests that the risk is very low, probably less than 1 in 10,000 vaccinations.

Is there a problem in combining different components in the same vaccine?

Multivalent vaccines are now available that can include all the common feline vaccines (including cat flu, enteritis, leukaemia virus and chlamydia) in a single injection. This has raised questions as to whether there are dangers or disadvantages of combining multiple vaccine components, particularly if this increases the risk of adverse reactions. There is no evidence that this is so and for any vaccine sold as a combination, studies have to be performed before a licence is granted to show that the combination does not adversely affect safety.

What should my cat be vaccinated against?

If you have concerns about this issue you should discuss it with your veterinarian who can assess the risk of infection to your cat and any relevant local issues. Decisions are based on balancing the very small risk of adverse reactions against the consequences of infection which can be severe and potentially fatal for some of the infectious diseases. For most cats the advantages of protection provided by vaccination will greatly outweigh any small risk of serious adverse reaction occurring. However, in some situations if exposure to an infectious agent is improbable vaccination may be considered unnecessary for an individual cat.

"Decisions are based on balancing the very small risk of adverse reactions against the consequences of infection which can be severe and potentially fatal for some of the infectious diseases."

How often should boosters be given?

Boosters have traditionally been given annually but questions have been raised in recent years as to whether adequate protection could be maintained giving boosters less frequently. This is a complex question to answer. For some diseases protection does probably last much longer than one year following vaccination but for others regular boosters are more important. For most vaccines, the manufacturer’s recommend that annual boosters should be given. If this is an issue of concern to you, you should discuss this with your veterinarian.

Are there any ways of reducing the risk of serious long-term adverse effects to vaccination?

In some cases if owners feel particularly strongly about this issue or have particular concerns, some components of the vaccine may be given separately at different sites, sometimes in the legs and tail. Another approach sometimes adopted is to note the site of vaccination and vary this every time a booster is given.


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