The trouble with rabies vaccines (including one possibility you may not expect)
If you’re a regular Dolittler reader you’ll know I’m a big proponent of routine rabies vaccination. I’ll even go so far as to raise the gruesome specter of the disease’s dreaded symptoms and universal fatality to get you to comply. I’m also not above using guilt along with scare tactics. Anything goes when it comes to mitigating the public health risk of rabies.
Why? Because I’ve had more than my share of close calls with this virus. And I don’t believe that declining a rabies vaccine every three years is in the best interest of the public at large, regardless of what you (or I, for that matter) may feel is best for your individual pet.
Sure, any vaccine carries risks. This one is no exception. The every-three-year protocols now widely available are built to minimize them. But there’s no denying that once in a blue moon (less frequently, actually) a pet will experience an adverse reaction to a rabies vax. No doubt about that.
Though they’re very rarely life-threatening, we know that every vaccine can theoretically lead to the kind of reaction evidenced by urticarial reactions (facial swelling or hives), fevers, respiratory distress, autoimmune diseases and even cancer.
This we know. And this we live with why? Because we’ve done the math and we know that the risk of widespread disease in the absence of vaccination is far worse than the individual risk of a reaction.
You don’t need to have lived through a parvo epidemic, a distemper outbreak or a colony-wide FIV infection to know this is true. You don’t even need to remember back to classmates with polio or the palpable fear of rabies back in the day to know that vaccines do their thing well. After all, it’s pretty obvious that smallpox and measles are nearly nonexistent entities as a result of modern medicine’s reliance on vaccination.
Yet ironically, it’s these very successes that are arguably to blame for the backlash against vaccination. They’ve made it much easier to for us to expect the kind of miracles even modern medicine can’t always provide (i.e., continued protection sans vaccination). Hence, the expectation that vaccination can be done away with once diseases are sufficiently under control...once the risk of vaccination starts to seem more harrowing than the disease itself.
Here’s where rabies serves as perfect example: Despite the undisputed excellence of our US rabies eradication program some seven thousand cases were reported last year. Of these, 300 of the rabies-infected were cats, which represents a 12% increase in feline cases––not an auspicious finding. And then there are the two dead humans to consider.
How many animals suffered vaccine reactions last year? Not sure. But the latest bit of independent research I have readily on hand is a feline study from 2002. It looked at 32,000 vaccine doses, for which 73 cats suffered localized tissue reactions (the most common kind of adverse vaccine event in cats). That’s a total of 11 cats in 10,000. And of these 32,000 cats, only 2 suffered potentially fatal sarcomas (the most feared feline vaccine reaction of them all).
It’s not a straightforward 1:1 kind of relationship to all rabies vaccinates and the risk of vaccination, but it gives you a rough idea. Is it worrisome? Yes. But it’s not a huge risk––not by a long shot. It’s what we call an “acceptable risk.”
Then there’s a new study to consider (sorry, not available online yet): For those of you who reckon your pets are safe after just one or two vaccines, think on this one:
In a retrospective study conducted between 1997 and 2001 (JAVMA Sept. 15, 2009), 41 states reported rabid cats and/or dogs. Of these, 21 submitted information on 264 rabid dogs and 840 rabid cats. Among the cases, 13 of dogs and 22 cats had been previously vaccinated at some point. 2 dogs and 3 cats were “current” on their vaccine and 1 dog and 5 cats had previously received two doses of the rabies vaccine. None had received more than two.
Scary, right? While vaccination is helpful, it’s not a surefire antidote to protection. That might give the anti-vaccination camp fodder, you might assume. Why assume the risk if one possible outcome is the lack of protection?
But you can see the other side, too? That’s the one that argues in favor of re-vaccination at regular intervals to secure the most effective immunity. Of course, it’s also true that pets who receive more than two rabies vaccines in their lifetime might also be those most unlikely to free-roam and interact with wildlife. An innate bias, indeed.
Either way you slice it, it’s clear that vaccination confers protections––albeit not perfectly. And we already knew that. Now the question is what percentage of the vaccinated pets in our midst are truly protected and how many are not. But unfortunately, that we cannot know. Not unless we challenge a sizable percentage of vaccinated pets with the virus. And we’re not about to do that. It’s neither safe nor humane.
Ultimately, it’s true. We do not have a crystal clear view of what the true risk of vaccination might be...not even if we measure all the reactions. Why? Because we can’t know whether protection is guaranteed in all cases.
Think about it: If protection is not necessarily conferred by rabies vaccine numbers 1, 2 or even 3 in some cases, the risk of reaction must take into consideration the additive, individual risk of all three vaccines. And there’s no good way to rub the Vaseline off the lens except through imperfect retrospective studies like this one.
Despite the additional murkiness studies like this inject into the already-muddied waters of the vaccinate-or-not debate, I can’t help but think there’s still no good reason to go without. I don’t care if your pet lives in a bubble, I’m still recommending vaccination––unless you can prove to me that he’s never had access to the outside world...unless you can convince me she never will.
Till then, I would hope you’d consider my position as a servant of public health. Because regardless of what might truly be what’s best best for your pet’s health (being the lone unvaccinate in a sea of vaccinates is undoubtedly ideal), I don’t believe the rest of the world deserves to suffer the heightened threat of rabies on the basis of our personal preferences.