How close are we to getting a vaccine for Lyme disease?

Yahoo

11-06-2025

Diana Moser has, to the best of her knowledge, not contracted Lyme disease, a welcome status quo that might be credited to the tick-repellant clothing she wears in the yard of her East LaHave, N.S., home, or to the insect spray she squirts on herself, or to just plain-old luck.
Or, it's possible the good fortune is due to what some are hoping is a "game changer" in the fight against the disease, which is caused by tick-borne bacteria and, if left untreated, can lead to severe heart, joint and nervous system symptoms.
Moser is one of dozens of people in Nova Scotia, and more than 9,000 in the eastern United States, Eastern Canada and parts of Europe, who are taking part in clinical trials for a vaccine against Lyme infection.
"I think it's incredibly important to have," she said of a vaccine, noting she knows at least four people who have contracted Lyme disease, including one who has had it multiple times.
"It's such a tricky disease, like when you get Lyme, so many things can happen. It causes joint pain, it causes inflammation. It really affects your system in a deep and abiding way."
There were more than 27,000 cases of Lyme disease recorded in Canada between 2009 and 2024, the majority of those in the last four years. Actual infection rates are higher, however, because cases go undetected or unreported, according to the federal government.
In the United States, over 89,000 cases were reported in 2023 to the Centers for Disease Control. In one study, researchers used insurance claims data to estimate that nearly half a million people a year may be diagnosed and treated for Lyme disease.
The vaccine furthest along the research pipeline is the collaboration between multinational pharmaceutical giant Pfizer and European vaccine company Valneva SE, with Phase 3 clinical trials scheduled to run to the end of December.
WATCH | How close are we to getting a vaccine for Lyme disease?:
A Pfizer spokesperson said if trials are successful the company could potentially apply in 2026 to the U.S. Food and Drug Administration and the European Medicines Agency for approvals to market the vaccine. There is no timeline for a similar application to Health Canada.
The clinical trials have targeted areas where Lyme disease is endemic. Participants were chosen for their increased risk, including landscapers in tick-infested areas, people who do a lot of hiking or gardening, or who have dogs that routinely come home with ticks attached.
Like all participants, Moser doesn't know if she has been injected with a course of the real vaccine and a booster, or simply been given a placebo, although she hopes to learn which it is once the trials end.
Some, but not all, blacklegged ticks carry Borrelia burgdorferi, the bacteria that causes Lyme disease. The ticks are tiny, living in woods, shrubs and long grass, attaching themselves to humans or animals that brush past the vegetation and then feeding on their blood.
When they bite, some of their stomach contents, including the bacteria, are eventually discharged into the bloodstream. In most cases, the tick must be attached for at least 24 hours before a person is infected.
The Pfizer-Valneva vaccine prompts the human body to create antibodies to a protein on Borrelia burgdorferi, according to Dr. Joanne Langley, a pediatrician with the Canadian Center for Vaccinology, a Halifax-based group helping conduct the clinical trials in Nova Scotia.
Ideally, if a Borrelia burgdorferi-carrying tick latches on to the skin, the vaccinated immune system will recognize the bacteria and attack and clear it, preventing Lyme disease, Langley said.
"It could be really a game changer for how we try to deal with Lyme infection," she said in an interview, adding that half of people who contract the disease don't even remember being bitten by a tick.
"It would be really great if we could be a little more carefree in the woods and just walking around our environment."
Found widely in the eastern United States, the first colony of blacklegged ticks in Canada was discovered in the 1970s in an Ontario provincial park on Lake Erie.
It has since become established in six provinces. In Nova Scotia, which has some of the highest tick numbers, populations are growing both in rural and urban areas, according to the provincial government.
What has perplexed some people who ritually pick ticks off their pets or who have been infected with Lyme is why it has taken so long to develop a vaccine, especially given Lyme vaccines for dogs have been available for years.
A Lyme vaccine for humans did hit the market in 1998, but was pulled in 2002 by the company that developed it, citing poor sales. Its reputation had been damaged by reports of adverse reactions, even though the FDA didn't find any evidence it was causing harm.
Thomas Hart, a microbiologist who studies Lyme disease at Johns Hopkins Bloomberg School of Public Health in Baltimore, said the controversy "just chilled the whole field."
"That's part of why we're only now seeing momentum again and bringing the Lyme disease vaccine actually through clinical trials in to market," he said.
Hart has not been involved with the Pfizer-Valneva work, but said it's a "real promising vaccine" and it will be a "big deal" if approved.
But it's not the only vaccine research. For instance, Hart said, scientists are examining vaccines aimed at deterring ticks from simply feeding on humans, protecting people not just against Lyme disease, but from other tick-borne infections.
Another strain of research attacks the problem from an imaginative angle — small food-like pellets coated in vaccine to inoculate, of all things, mice. It's an idea conceived by Dr. Maria Gomes-Solecki, a veterinarian and microbiologist at the University of Tennessee Health Science Center.
Mice and ticks, she said, infect each other with Borrelia burgdorferi. Vaccinating mice attempts to break the cycle. That brings down the prevalence in an area of ticks that have the bacteria, which in turn cuts the risk of humans getting Lyme disease.
"One strategy alone is not enough to control this disease," she said in an interview.
The company US Biologic has been marketing the product for about a year and a half, according to president Chris Przybyszewski. Pellets can tossed using a scoop — at intervals at the sides of trails, for instance — or deployed near homes in small circular "stations."
The product is aimed at homeowners, golf courses, summer camps, outdoor athletic facilities and pest-management outfits. The company is also working with governments to deploy it on public lands, he said.
The pellets, shaped like acorns, don't provide any nutritional value and don't attract other animals, Przybyszewski said. But the mice will eat them, he said, and research shows they can cut the rate of infected ticks in an area by 75 per cent.
There are plans to eventually bring the product to Canada, he said, with US Biologic likely to begin seeking approval this year or next.
"I think it's just incredibly important that we pay more attention to this kind of concept, really focusing on products and programs that can make a difference and really create a new way of stopping infectious diseases," he said.
For Colin Chase, a participant in the Pfizer-Valneva vaccine clinical trials, ticks are a fact of life, both as someone with a deep love of the woods, and as a volunteer search and rescuer who routinely clambers through dense Nova Scotia forests.
Searchers take the full range of precautions, he said, examining each other for the tiny creatures, stripping down before they go inside their homes and throwing their clothes in the dryer and then the washer. Many have a favoured anti-tick spray they swear by.
But even with those efforts, ticks can still sneak in and become embedded on the skin. If a vaccine is safe and effective, Chase said, why wouldn't someone take advantage?
"Because otherwise the alternative is, 'Oh, I'm not going to go in the woods. I'm going to disconnect myself from the natural environment.' And there's so much beauty in the woods," he said.
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