Rabies Titer Gone? Research: Protection is Not!

New Study Says More Than It Lets On

I stumbled on some very hot news in the research world the other day. Hot, because it affects how you think about rabies vaccinations, a sore spot for many of you. The lead author is Michael Moore, D.V.M, Ph.D. who heads the Kansas State Veterinary Diagnostic Laboratory.

This is the lab that runs rabies titers for probably all of North America, and maybe beyond. If you ask your local vet for a rabies titer (and don’t get a quizzical look, “Titer??”), or you ask Dr. Jean Dodds to do it, this is where your animal’s blood gets sent.

As a quick review, a titer is a measure of the antibodies in the blood. Antibodies can come from exposure to disease (like Ida, my dog patient fighting Lymes) or from vaccinations. I’ve warned about over interpreting the latter results, which could result in revaccinating your animal unnecessarily. It’s important that you understand this, if you want to intelligently avoid vaccinations.

Lies, Damned Lies, and Statistics. Oh, and Revelations.

The study, published this week in the Journal of the American Veterinary Medical Association is titled, “Comparison of anamnestic responses to rabies vaccination in dogs and cats with current and out-of-date vaccination status.”

It reveals some interesting facts, buried in scientific jargon and statistical analysis guaranteed to give the average reader a headache. [Anamnestic means immune memory response. Think of it as the booster effect.]

One of those facts ought to be of great interest to you. It corroborates something I’ve said for years, based on a conversation with Dr. Ron Schultz over 20 years ago. It’s the fact that one year rabies vaccines and three year rabies vaccines are identical.

Want to reread that? It’s as true now as it was 20 years ago. No difference between 1-year rabies vaccines and 3-year rabies vaccines.

Here’s what the researchers wrote in their peer-reviewed journal article:

The 2 animals with current vaccination status that were quarantined had been exposed > 1 year (but < 3 years) after receiving a rabies vaccine labeled for 1-year duration. However, the manufacturer confirmed that the 1-year and 3-year formulations of this product were identical…”

Here it is again, in the same article, in a deniability statement that would be rival the CIA being questioned about dirty tricks on foreign soil:

One animal that received a 1-year vaccine was excluded from the data analysis because the company that manufactured the vaccine would neither confirm nor deny that their 1-year and 3-year formulations were identical.”

The company in question? Merial, maker of Imrab 3, Imrab 1, and Purevax. And yes, the labels for the first two claim to provide three year duration of immunity and one year duration of immunity respectively.

If you’ve been following along, neither of those claims is likely true. Immunologists tell us the immunity from a virus vaccine is much, much longer in duration. Likely lifelong.

Rabid Skunk Bites Your Dog. Who You Gonna Call?

This research paper studied what happens to your dog or cat if she is bitten by a rabid animal, and given a rabies booster soon after. That’s the standard of care for bitten animals, generally: they are given a booster vaccine with the hopes that they make a rapid enough immune response to prevent them from succumbing to rabies.

You remember the scary stories from 40 years ago? A person is bitten by a skunk. The skunk is tested and found to be rabid. The bitten person gets 14 shots in the abdomen! Ouch!

Well, that doesn’t happen any longer. The shots are given in muscles now, and the number is more like 3 or 4. And those shots? They are antibodies, not vaccines. The goal is to get antibodies into the bitten person to quickly neutralize any rabies virus that came from the bite.

The study set out to learn if there was a significant disadvantage to the animals who were “out of date” on their rabies vaccinations as compared to those considered “up to date.” (Again, if you’ve been following the logic of the long DOI (duration of immunity) that comes from viral vaccination, you know this is a moot point.)

What’s The Protocol for Your Bitten Animal?

(Remember, this has nothing to do with humans being bitten by your dog or cat, this is all about your animal being exposed to a rabid or presumed rabid animal.)

There’s a large tome written about rabies, called the Compendium of Animal Rabies Prevention and Control. It’s published by rabies scientists and public health veterinarians known collectively as the National Association of State Public Health Veterinarians, Inc. (NASPHV). This guides the response to an animal or a person exposed to rabies. Remember, rabies is a potentially human disease, so health departments get involved.

The intent of these guidelines is to prevent the spread of rabies in animals and people. Here’s what they say about a pet bitten by a rabid animal.

1. Pets with “current” rabies vaccination status that have been exposed to known or suspected rabid animals should immediately get a rabies booster vaccination and be observed for 45 days under the owner’s supervision.
2. Animals never vaccinated for rabies who’ve had a similar exposure to a rabid animal are to be either euthanized or quarantined for 6 months in a specialized facility.
3. Dogs and cats exposed to rabies who’ve been vaccinated but are deemed “out of date” (according to the labels of their respective vaccines, again 1-year or 3-year) are evaluated on a case by case basis. Considerations include,

• How severe was the exposure?
• How long since the last rabies vaccination?
• How many rabies vaccinations were given in the past?
• How healthy is the exposed animal?
• How much rabies has been reported in the area?

Who Did They Study?

The researchers at the rabies lab measured two groups of animals, a mix of dogs and cats:

1. Current vaccinates

2. Out of date vaccinates

Both groups were defined purely by the manufacturers’ vaccine label. Now, we all know those labels have precisely this much basis in immunology:

0%. Nada. Not a lick.

Who says so? Veterinary immunologists, who make no money selling vaccinations but who study the vaccines and their effects in animals.

That being said, “current” vs “out of date” is real to officials in public health apparently, and those were the two groups of rabies-exposed pets compared in this research.

Both groups were given a booster rabies vaccination and their rabies titers were measured at 5 to 15 days post vaccination. These rabies titers (measures of rabies antibodies in the blood) were then compared to the initial rabies titer taken upon intake.

The Envelope, Please

The findings were actually quite remarkable, even to someone like me who is far from an expert in statistics. The design of the study compared the current vaccinated group with the out of date group by a statistical method called “noninferiority.”  In other words, the test was to determine if the out of date group would respond worse or the same as the current group. “Better than” was not in the cards to measure, apparently.

But the out of date group actually responded better than the currently vaccinated group! Animals out of date for a long as 46 months jumped at the chance to make protective antibodies once they were given a booster rabies vaccination. Their rabies titers increased very quickly (that’s the anamnestic or memory response).

NONE of the out of date test animals failed to make a titer far exceeding what the World Health Organization considers a “protective titer” of 0.5 IU/ml.

What Was Learned About “Out of Date” Animals?

Though the intent of the study was not to find anything positive about those out of date animals, these data don’t lie. They did really well!

Most of those out of date rabies exposed animals had protective rabies titers already, before being boosted. Some of them were years out of date, yet antibody at protective levels remained in their blood.

Further, some animals, “out of date” by label regs, came in with no measurable titers. Others tested low, with “non-protective” titers (< 0.5 IU/ml).

Gulp. Your worst fear? You’ve stopped vaccinating, told your vet “No more!” after learning about the long DOI for virus vaccinations (and the potential for harm from giving more), and now you’ve got an animal who’s no longer protected?

No. Far from it.

100% of those getting booster vaccines, regardless of their status, showed protective antibody levels 5-15 days later. Every last one of them.

Some of the more dramatic were a few dogs who had supposedly no protection whose rabies titers jumped to 12 IU/ml, the highest level reported. [Note, the study lumped every animal with a titer of 12 or greater as simply 12. You can bet there were even higher titers.]

Here’s one of the graphs from the study that has some stories to tell. Click on it to enlarge it.

What You Can Learn from This Study (Even Though Its Intent Was Quite Different!)

This study sought to prove or disprove that animals considered “out of date” on their rabies vaccinations were inferior in protection capability to a live rabies challenge. I suspect the researchers were quite surprised at just how well the out of date dogs and cats did.

Quoting the paper,

Dogs with out-of-date vaccination status had a higher median increase in titer, higher median fold increase in titer, and higher median titer following booster vaccination, compared with dogs with current vaccination status. However, statistical analyses were not performed on these parameters. [Emphasis mine]”

I can imagine the conversation before deciding how much of these findings to report. Researchers and maybe journal reviewers had concerns. That’s my best guess.

“Hmmm, it sure looks like the out of date dogs smoked the up to date ones in how well they responded to our booster rabies vaccine!”

“Yeah, but we’ve got to decide what we want the pet owning public to take away from this, right? I mean, Dr. WhiteCoat would come at us with scalpels and 12 gauge needles if we let it out that the non-compliers actually did better than the ones who kept repeating vaccines every year or three, wouldn’t he?”

“Oh my, yes. How about we just say we didn’t assign statistical significance to that remarkable performance by the out of date dogs?”

“Brilliant. I can take that to press. That should keep the pitchforks from coming our way.”

But, data is data. Here’s a well done study of 74 dogs and 33 cats that showed all of them, regardless of whether they’d been kept up to date with rabies vaccines or only had one years ago, could respond to a booster after a rabies exposure. A response that should translate to protection against rabies.

It makes me wonder how the exposed would respond to just the rabies virus in the bite itself? I suspect, even without the recommended booster vaccination, they’d do just fine.

Feeling Better About Your Decision?

I hope this helps you clarify your stance that “once and done” with a virus vaccine is likely to confer a long lived immunity in your animal. You have more science on your side now, behind stopping repeated vaccinations. You can add this research to your Evernote or what ever else you use to keep track of things in your life.

I have a feeling this may not be freely available online for too long. There are likely a number who’d like to “disappear” it to help keep up the façade that repeated vaccinations throughout life is the responsible course for pet owners to take. Better copy it before that happens.

Let us know in the comments if this helps you in your present decision not to repeat vaccines. Or if it helps you now decide that all those postcards to repeat vaccinations aren’t worth the paper they’re printed on.

Photo Attribution