Right now, my dog can get vaccinated against Lyme disease, but I can’t. The last human Lyme vaccine was pulled from the market 20 years ago, but that might be changing as Lyme cases increase—thanks in part to climate change. Now, a new vaccine is in late-stage clinical trials and could be available as soon as 2025. On Sunday’s episode of What Next: TBD, I spoke with Cassandra Willyard, a freelance science journalist based in Madison, Wisconsin, about why it took so long to get to this point. Our conversation has been edited and condensed for clarity.
Lizzie O’Leary: Lyme disease is caused by a tiny bacterium called Borrelia burgdorferi. Under a microscope, it kind of looks like ramen noodles. Borrelia travels on blacklegged ticks, which like to bite rodents and deer and humans. Often, when a Lyme infected tick bites, you get the famous bull’s-eye rash, but not always. Back in 1998, when I was graduating from college and hiking on wooded trails in Massachusetts, I learned to check myself for ticks. Lyme wasn’t that common then. According to the CDC, there were about 17,000 cases that year, mostly in the Northeast. That was also the year the FDA approved LYMErix, which was …?
Cassandra Willyard: It was a vaccine for Lyme disease. The studies suggested that it was about 76 percent effective. It was only on the market for a few years, and then the manufacturer pulled it off the market because sales tanked.
Now that we’re all armchair epidemiologists, the idea of a vaccine that’s 76 percent effective sounds great. But LYMErix never really took off with the public.
One reason is, perhaps, that Lyme disease was a lot less common then. Case numbers have increased a lot over the decades; the numbers now are about three times what they were in the ’90s. So there probably wasn’t as much demand then as there is now. Partly it was this sense that there were some potential side effects. After the vaccine started being administered, people started complaining about some of the same symptoms that people who have untreated Lyme complain about, like joint pain and arthritis. It was never proven that that was linked to the vaccine, but it left a bad taste in everyone’s mouth.
On top of those concerns, a strange phenomenon was taking shape. There was an idea that Lyme was something that only affluent, anxious individuals were concerned about. Maybe because they tended to live in places like Lyme, Connecticut. And it wasn’t just members of the public who felt this way. When the CDCs Advisory Committee on Immunization Practices, the ACIP, meant to discuss the vaccine in 1998, it got a derisive nickname. What’s the story behind that?
One of the members of the ACIP actually said something like, “This is as yuppie a vaccine as I’ve ever heard of.” And I don’t know why it was viewed as a yuppie vaccine or why Lyme disease would be viewed as a yuppie disease. I think some of it was that there are other ways to prevent Lyme disease. You can prevent ticks from biting you by tucking your pants into your socks and wearing a bunch of bug spray, that sort of thing. So I guess to some people, maybe a vaccine felt like overkill.
Partly that was because there were simply fewer cases, but also because Lyme and its long-term effects weren’t fully understood or seen as a big deal medically. Why was that the case?
The research back then suggested that if you treated Lyme disease, you solved the problem. It was easily treated. That’s still many people’s view today, but what we’ve learned over the past several decades is that it’s a little more complicated than that. Lyme disease is sometimes difficult to spot early on. We know a lot more now and I don’t think it’s as straightforward as we thought it was back in the late ’90s, early 2000s.
Eventually, the manufacturer of LYMErix pulled the vaccine from the market, citing poor sales and limited demand. What do you think that did to the research and development around Lyme vaccines in general?
It had a huge chilling effect on all that research. There was another company who was developing a Lyme vaccine. Their results from their vaccine came out right around the same time that LYMErix published its results, and they just dropped it. Then, another vaccine manufacturer was developing a vaccine in the 2013-ish range, and they just abandoned that research and never pursued it.
Now there’s a new Lyme vaccine that might come to market. Can you walk us through why this one might be different from previous attempts?
Let me give you a little bit of background on how LYMErix worked. It was a really interesting and unique mechanism. You get the vaccine, and you develop antibodies to a particular protein on the surface of the bacteria called ospA. When a tick bites you, it takes in blood from your body and with that blood is these antibodies to ospA. Then, the antibodies basically kill the bacterium inside the tick, so you’re never getting the bacteria at all.
When LYMErix was on the market, there was a concern among some vaccine recipients that targeting the ospA protein was what led to side effects like achiness and arthritis. No research ever linked them. How does the new vaccine get around that problem?
They have just removed that particular chunk of ospA from their vaccine. The other main difference is it targets, I think, six different strains of Borrelia, not just the one that LYMErix was targeting.
This is in a Stage Three clinical trial. Pfizer and Valneva recently said they want to submit their data to regulators by 2025. What do you think it would mean to have a Lyme vaccine on the market in a few years?
It would be great. This is a big public health problem these days. I know a lot of parents are really worried about sending their kids out into the wild unprotected from Lyme disease.
Cases of Lyme disease have increased significantly since the era of LYMErix. In 2021, there were about 35,000 confirmed cases, double that of the 1998 caseload. But since so many cases of Lyme go undetected, the real number could be more like 300,000. But I wonder what kind of environment a Lyme vaccine would be moving into. Are there things that make you think that a new Lyme vaccine might have a better path to the market than the ones did 20 some odd years ago?
I have mixed feelings. I feel like in some ways, Lyme disease is a bigger problem now than it was, which bodes well for a Lyme vaccine being used. Also, I feel like the anti-vax movement is stronger than it was back then.
It’s still not clear if the hangover from the LYMErix saga would make today’s patients more or less likely to want a vaccine.
There are a lot of Lyme disease advocates, and you would think that they would be on the side of vaccination, but I don’t feel like that’s necessarily the case.
“Chronic Lyme” is a hotly debated issue. Researchers tend to view it as sort of a post-Lyme infection syndrome, and there’s some debate about what chronic Lyme is and how it should be treated. There’s a lot of advocacy that has built up around chronic Lyme. I think some people in the chronic Lyme community—and it’s not a monolith, they don’t all think the same thing—but I think some people would be skeptical about a new vaccine and worried that the question of the side effects of LYMErix never got adequately resolved. There was never a satisfying conclusion into what was going on in those people that were reporting arthritis and other symptoms after vaccination.
A new Lyme vaccine would obviously be entering into a very different landscape. Is it just that Lyme has gotten more widespread? How has that environment changed?
Part of it is just the spread of the disease out of the East Coast. Part of it is definitely climate change. The ticks are very sensitive to temperature and there is this thought that they’re going to be able to spread northward as the winters get milder up north. They’re already in Wisconsin, Minnesota, but North Dakota, northern Minnesota, Canada, those are places where ticks and Lyme disease could become prevalent. Part of it is just land use changes. Deer are implicated in all of this because they are a big source of food for ticks. Where there’s a lot of deer, there tend to be a lot of ticks and deer are dependent on land use changes. They like that sort of marginal forest bordering on open landscape. It’s all a bunch of complex answers about how we use the land and how the land is changing and how the climate is changing and how different species are adapting to that climate change.
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