Vaccination: Efficacy

Does it Work?

Animal - Jumping Dog
Every procedure we do to ourselves or those in our care should be a useful one or there is no reason to do it. Obvious perhaps, but common sense is less and less common of late, especially in the world of modern medicine.

While vaccinations may confer immunity in animals, how effective or useful is it to repeat this procedure every year, as is the standard recommendation in this country today? How about every few years? Let’s dig in and find out.

You vs Your Dog/Cat/Horse

Immunology has recognized for a great many years that viruses confer a long-lived immunity. This is why your physician is not sending you postcards every year to repeat your small pox or polio vaccinations annually.

Your physician understands that your immune system was adequately stimulated in childhood, and a cellular memory exists in you that will “wake up” if any future challenges from these viruses occur.

Is there some profound difference in animals that makes us think they need to repeat their vaccinations throughout their life?

The Experts Speak

Let me quote from the experts. The following was printed in Current Veterinary Therapy, Volume XI, published in 1992 (this is a very well-respected, peer-reviewed textbook that is updated every four years).

The authors are veterinary immunologists Ronald Schultz (University of Wisconsin) and Tom Phillips (Scrips Research Institute).

They are addressing the “Does this work?” question directly here:

A practice that was started many years ago and that lacks scientific validity or verification is annual revaccination. Almost without exception there is no immunologic requirement for annual revaccination. Immunity to viruses persists for years or for the life of the animal…
Furthermore, revaccination with most viral vaccines fails to stimulate an anamnestic (booster) response…. The practice of annual vaccination in our opinion should be considered of questionable efficacy…”

In plain English, that means you are wasting a lot of money (and, as we’ll see later, risking your animals’ health) without much likelihood that your animal is actually becoming “boosted” each time you revaccinate.

In other words, the immunity that was established in early life persists, and it is that immunity that actually interferes with subsequent vaccinations.

It’s akin to vaccinating very young puppies. If you vaccinate a puppy (or kitten or foal) at a too young age, the maternal antibodies from the mother’s colostrum are still present, and the vaccine will be thwarted in its attempt to provoke an immune response.

Types of Rabies Vaccines: “1 Year” or “3 Year?”

I had the pleasure of meeting Dr. Schultz at a veterinary conference several years ago. He has done research for many of the companies that market vaccines. It was very interesting to hear his perspective of 25 years in this field. He clearly had not come to this understanding lightly.

One most interesting fact was how rabies vaccine comes to be labeled. We currently have both a “One-year rabies” and a “Three-year rabies” vaccine. On the labels, the one-year must be repeated yearly and the three-year must be repeated every three years.

The two labels relate to the length of time the experimental animals were studied. At the end of one year after their vaccination, the animals were challenged with live rabies virus, the survivors tallied, and the vaccine marketed as “One-year rabies vaccine”.

The same vaccine was studied for three years, the data gathered, and this vaccine lot was marketed as “Three-year rabies vaccine.”

Rabies vaccine is so effective in immunizing that there is likely life-long protection if you don’t start too early. (Note: minimally, wait till after 4 months of age. Six is even better).

Why then do some vaccinate annually? Unfortunately, we have laws in place that fail to recognize immunological facts. A handful of states still require annual rabies vaccination.

In Texas and most US states all dogs and cats are required to be vaccinated triennially against rabies. Counties can supersede state laws, which adds even more complication.

Summing up vaccination efficacy:

  • Vaccines confer long-lived immunity (high efficacy)
  • Vaccination repeated in the face of existing immunity doesn’t work (low/no efficacy)
  • Rabies is complicated by human health laws
  • If you have a vaccinated animal, I advise not re-vaccinating
  • Why not more? For safety reasons.

Rabies is covered here.

For now, suffice it to say that if your dog or cat is an adult who has had vaccinations, there is no immunologic need to continue vaccinating annually: the immunity is present from the early vaccines and will not get any better through yearly repetition.

Nor will it improve with the now popular triennial vaccination schedule.

Hey, you’re doing great! Ready for more?

Vaccination: Safety
Vaccination Waiver
Vaccination Rabies
Vaccination Non-Rabies
Fallacy of Titer Tests