VACCINES: The Basics

Vaccines are not as straight forward as you think.

A vaccine is a biological substance used to stimulate a cat’s immune system to provide future protection against a disease.  It may contain an inactive organism (i.e. rabies), a weakened organism (i.e. some FVRCP vaccines), a toxin, or a protein from the organism.  Once administered, your cat’s immune system will recognize this foreign substance, build a specific response, destroy it, and then continue this process in the future.  Some vaccines prevent your cat from acquiring a disease (i.e. rabies) while others minimize how “sick” your cat becomes when infected (i.e. FVRCP). 

Historically, vaccines have been the most effective way to fight against and eradicate disease in a population.

For a vaccine to work, it must be administered to a healthy cat (this is why an exam is required for a vaccine).  Since we are dealing with live biological systems, there are a few things that may occur:

• If your cat does not have a strong immune system, the effectiveness of a vaccine may be limited.

• Your cat may be up-to-date on their vaccines but the body cannot react fast enough to an infectious organism, which may result in illness.

• Sometimes an infectious organism mutates or changes (i.e. a new dog distemper strain entered Canada from South Korea last year). In this case, your cat’s immune system may not be able to control the infection 100% and needs to adapt.

• Some vaccines just “work better” against some diseases than others.  Rabies and panleukopenia (The “P” in FVRCP) vaccines are very effective.  The vaccines against upper respiratory viruses such as herpesvirus (the “FVR” in FVRCP) and calicivirus (the “C” in FVRCP) are not as effective.  Their goal is to minimize illness (think of the flu vaccine for humans).

• Different vaccine “types” can be more or less effective against different strains of infectious diseases.  This is why we administer a killed, injectable FVRCP and a live, intranasal FVRCP to kittens during the FVRCP vaccine series.

• If your cat has not been vaccinated according to protocol (i.e. the kitten vaccine series was not completed), protection may be less than ideal. For example, antibodies from mom may inhibit a kitten’s immune system from properly responding to a vaccine.  Since it is difficult to predict when the antibodies from mom will wane in individual kittens, it is recommended that all kittens be vaccinated until at least 16 weeks of age.

As infectious organisms continue to change,
so will vaccines and their protocols.

The main goal of any vaccine protocol is to
avoid serious illness and possible death. If a vaccinated cat acquires a
disease, they typically have much milder symptoms than if they were not
vaccinated.  The benefits of vaccinating
your cat far outweigh any potential risk that may exist (except for a severe
anaphylaxis reaction, which is extremely rare). 
The anti-vaccine trends that exist today are supported by false
narratives and nonscientific data (more in a later blog).  All cats should be vaccinated against rabies
(required by law) and FVRCP.  Cats who
spend time outside should also have the feline leukemia vaccine.