Why is there no human vaccine for Lyme disease? We have medication to prevent tick bites—and Lyme—in dogs, after all.—Karen McCullough, via email
Actually, there used to be a vaccine. In 1998, the FDA approved LYMErix, a “recombinant” (or “subunit”) vaccine. This type of vaccine contains a portion of the pathogen—not enough to make you sick, but enough to trigger an immune response and “teach” your body how to defend itself. But, by 2002, the vaccine’s maker had voluntarily discontinued it. According to the CDC, the company cited “insufficient consumer demand.” Of course, there’s more to the story. (There usually is.)
“The previous human vaccine was under-utilized in part due to a vociferous push back from Lyme disease advocates,” says Gerald Evans, an infectious diseases expert at Queen’s University in Kingston, Ont. They raised concerns that it caused chronic problems in people who received it, despite debatable evidence.
A new tick repellant is on the horizon for Canadians
Happily, there are new vaccines in the works. Slowly. Because developing a vaccine for humans can take 10 to 15 years. “They go through much more rigorous testing and approval processes than medications for veterinary use, including short- and long-term randomized controlled trials,” says Evans.
Plus, the type of illness that you’re trying to vaccinate against can complicate vaccine development. “Immunity to bacteria is, in general, more challenging than that for viruses,” he says. “In particular, Borrelia bacteria are known to vary their antigenic structure.” Translation? This sneaky Lyme-causing bacterium has the ability to alter itself on the surface—like a shape-shifting alien in a movie—to avoid a host’s immune system response, allowing it to “escape” and wreak havoc. “This means that an immune response to a vaccine may not adequately protect a host from developing the clinical symptoms of infection,” says Evans.
When will a Lyme disease vaccine be available in Canada?
Okay, so creating a human Lyme vaccine isn’t simple. But there may be an additional hurdle: the LYMErix failure left its mark, says Evans. So, never mind the expected challenges of making a successful vaccine, and never mind the fact that Lyme is far more prevalent these days, “I would speculate that commercial vaccine developers may be somewhat reluctant to work with researchers on a vaccine given the history of the previous one being effectively forced off the market,” says Evans. “In addition, the ongoing rise of anti-vaccine sentiment now being seen in the U.S. and globally is a major deterrent.”
This article originally appeared in the Winter ’25 issue of Cottage Life.
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