- Lyme disease is becoming common in more parts of the U.S., but there are currently no Lyme vaccines on the market.
- There are multiple Lyme disease vaccines in the pipeline, including one that could be available next season.
- One product in development is a prophylaxis that delivers antibodies directly to the vaccinated person, rather than asking the immune system to produce antibodies, as traditional vaccines do.
Spring is turning to summer and the ticks are ready to start biting.
As climate change shortens winters, warm-weather-loving ticks stay active for longer. Meanwhile, construction developments break up ecosystems, and the deer and mice that act as reservoirs for the Lyme-causing bacteria romp through suburbs unchecked.
The number of Lyme disease cases reported to the Centers for Disease Control and Prevention (CD) has more than doubled in the last 20 years. More than 475,000 people are diagnosed or treated for Lyme disease each year, according to CDC estimates. Once contained to small sections of the Northeast U.S. and Midwest, Lyme disease cases have skyrocketed in those regions, and tick-borne diseases are proliferating in Western states.
The rash, fever, and fatigue that typically accompany Lyme disease usually clear up after a few weeks of oral antibiotic treatment. But if left untreated for long enough, the disease can spread to the heart, joints, and nervous system, causing pain and difficulties thinking for more than six months after treatment.
But there is no pharmacological way to prevent Lyme disease from taking hold after a tick bite—at least not in humans. Dogs have been getting vaccinated against Lyme for more than 30 years.
That could change very soon. A vaccine by Pfizer and Valneva is in stage 3 clinical trials and could be ready for the next tick season. Moderna has two vaccine candidates in the works. And a novel prophylaxis shot developed by researchers at the University of Massachusetts could give seasonal protection, even for people who have a hard time mounting an immune response.
A Fraught History of Lyme Vaccines
Twenty-five years ago, a vaccine called LYMErix debuted. It was shown to be 76% effective at preventing Lyme disease.
But by 2002, vaccine manufacturer SmithKlineBeecham pulled it from the market due to poor sales. The company faced a class action lawsuit alleging that LYMErix caused arthritis in vaccine recipients. Multiple Food and Drug Administration (FDA) investigations concluded that the vaccine wasn’t to blame, but demand for the vaccine had already plummeted.
For decades, other companies kept out of the market, fearing the same outcome.
But Lyme is no longer considered a rare disease, and increasingly greater portions of the U.S. population live in areas where Lyme is endemic, said Sam Telford, MS, SD, professor of infectious diseases and global health at Tufts University, who helped run the LYMErix clinical trials.
“Mothers are fed up with checking their children for ticks every day,” Telford told Verywell. “It affects people’s quality of life. If they can’t enjoy their backyard, if they can’t go out and walk in the woods to pick blueberries, have their children play in the yard without worrying about them kicking a ball off into the edge of the yard, that diminishes from the enjoyment of their home and community.”
About 85% of Lyme cases in the U.S. occur between Memorial Day and the end of July, when young ticks the size of poppy seeds can go unnoticed. If an infected burrowing tick goes unnoticed for more than a day, its saliva can enter its host’s bloodstream, passing along Lyme-causing bacteria.
A New Type of Prevention Shot
Most vaccines work by introducing a version of the bacteria or virus into the body. These inactive antigens trigger the immune system to create antibodies that can attack the real pathogen, should it ever enter the body.
A group of researchers at MassBiologics are taking a different approach—a prophylaxis shot that delivers monoclonal antibodies directly to the individual.
When a tick bites, it sucks up some of the host’s blood into its stomach. If that individual is protected with Lyme PrEP, as the product is currently called, the tick will ingest some antibodies, too. These neutralize a key protein on the outside of Borrelia burgdorferi, the bacterium that causes most cases of Lyme disease in the U.S. This keeps the bacteria stuck in the tick’s gut and out of the host’s bloodstream.
People living in places where Lyme is endemic could get a dose that will protect them for the duration of tick season, according to Mark Klempner, MD, professor of medicine and executive vice chancellor for MassBiologics at the University of Massachusetts Chans Medical School.
For people traveling to a high-tick area, such as those on vacation or military personnel being deployed, a one-time small-dose PrEP shot could be much more temporary, staying in their system for only a few weeks or a month.
“Depending on the dose, we think that your protection could be tailored for anywhere from a month or two months, if that’s all you wanted or needed, to up to nine months,” Klempner said. “I think most consumers today think, ‘I want to take a medicine when I need it, and then I want it to be gone.’ And that’s the kind of thing that you can do with a monoclonal antibody.”
The Lyme bacteria is a weak antigen, which makes it difficult for most people to mount an immune response. Giving the antibodies directly to the individual, rather than asking the immune system to produce them, means people receiving Lyme PrEP are likely to be protected regardless of the strength of their immune system, Klempner said.
Besides, the immune response spurred by a traditional vaccine can come with uncomfortable side effects that can sometimes feel like the symptoms of the disease it’s trying to defend against. So far, Klempner said the only adverse reactions to Lyme PrEP have been some injection-site pain.
Lyme PrEP has only been tested in a phase 1 clinical trial to date. Future trials will test the duration of protection and other key safety and efficacy measures. Klempner said his team plans to run a phase 3 clinical trial next summer and seek FDA approval in 2025.
A More Traditional Vaccine Could Be Available Next Summer
The vaccine that is closest to the finish line is being developed by Pfizer and Valneva. VLA15, as it’s called, is a three-dose vaccine that trains the immune system to create antibodies that handicap Borrelia in the tick’s gut, just as Lyme PrEP does.
According to the companies, phase 2 clinical trials showed the vaccine was safe in people as young as 5 and protective for more than six months. In February, the companies announced that the phase 3 trial is delayed as they had to discontinue half the study participants for issues unrelated to safety.
Both VLA15 and Lyme PrEP target the same Borrelia protein as the ill-fated LYMErix did. Will this time be different?
The answer, Telford said, is probably yes. Unlike the makers of LYMErix, Pfizer and Valneva conducted safety trials early on and included children in their studies.
In addition, general interest in protection from Lyme disease appears to be high. A 2022 study found that nearly two-thirds of survey respondents were willing to get a Lyme disease vaccine, while 7% were totally unwilling.
“It’s hard to believe anyone would argue against trying to protect children,” Telford said. “I remain optimistic on that front, but I do worry that there is going to still be some activism against the vaccine.”
For people who are skeptical of a traditional vaccine, Lyme PrEP could be more appealing.
“There’s a lot of advantage to having choices,” Telford said. Everybody has their own picture of risk and their own picture of what they think they need. Having more than one option is going to be fantastic for everybody.”
Other Ways to Prevent Tick-borne Illness
While Lyme is the most common of the tick-borne diseases, it’s not the only one, said Neeta Pardanani Connally, MSPH, PhD, professor of biology and Director of the Tickborne Disease Prevention Laboratory at Western Connecticut State University.
Ticks in the U.S. can carry pathogens that cause 16 diseases, including Powassan virus disease, ehrlichiosis, and babesiosis. Anti-Lyme vaccines won’t protect against these other diseases.
“People should familiarize themselves with the types of ticks that live in their region and should make sure to take preventive measures for themselves, their kids, and their pets,” Connally told Verywell in an email. “We recommend bathing after outdoor activity, performing daily tick checks, and using a tick preventive product on ticks all year long.”
Wearing long pants, long-sleeved shirts, and other protective clothing makes it more challenging for ticks to latch onto your skin. Wearing socks and pants treated with permethrin or other EPA-registered repellents can repel ticks. Raking leaves and removing excess vegetation can make a yard less habitable for ticks.
Just as most people automatically reach for a helmet before getting on a bike, or buckle themselves into their seat, they should also reach for insect repellent to protect against tick- and other insect-borne infections, Telford said.
“Yes, it’s unpleasant to get bitten by a tick. Yes, it’s a terrible thing to get sick from a tick bite,” Telford said. “Nonetheless, people should not be afraid to go outside. It’s good for your health to be outside to enjoy nature.”
What This Means For You
There is no human vaccine for Lyme disease yet, but there are steps you can take to prevent infection. If you live in a place where Lyme disease is endemic, experts recommend checking for ticks daily. Remove the tick promptly, shower afterward, and watch for signs of fever or other symptoms of Lyme disease.