Key learning points
- Lyme disease is becoming more common in more parts of the US, but there are currently no Lyme vaccines on the market.
- Multiple Lyme disease vaccines are 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 make antibodies, as traditional vaccines do.
Spring turns into summer and the ticks are ready to bite.
As climate change shortens winters, warm-weather-loving ticks stay active longer. Meanwhile, building developments are breaking up ecosystems, and the deer and mice that act as reservoirs for the Lyme-causing bacteria romp uncontrollably through suburbs.
The number of Lyme disease cases reported to the Centers for Disease Control and Prevention (CD) has more than doubled in the past 20 years. The CDC estimates that more than 475,000 people are diagnosed or treated for Lyme disease each year. Once confined to small parts of the US Northeast and Midwest, Lyme disease cases have skyrocketed in those regions, and tick-borne illnesses are proliferating in Western states.
The rash, fever, and fatigue typical of Lyme disease usually clear up after a few weeks of oral antibiotic treatment. But if left untreated long enough, the disease can spread to the heart, joints, and nervous system, causing pain and difficulty thinking for more than six months after treatment.
But there is no pharmacological way to do that prevent Lyme disease after a tick bite, at least not in humans. Dogs have been vaccinated against Lyme for over 30 years.
That can change very quickly. A vaccine from Pfizer and Valneva is in phase 3 clinical trials and could be ready for next tick season. Moderna has two candidate vaccines in the works. And a new prophylaxis shot developed by researchers at the University of Massachusetts could provide seasonal protection even for people who have trouble mounting an immune response.
A fraught history of Lyme vaccines
Twenty-five years ago, a vaccine called LYMErix debuted. It was found to be 76% effective in 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 was not to blame, but demand for the vaccine had already plummeted.
For decades, other companies stayed out of the market, fearing the same outcome.
But Lyme is no longer considered a rare disease, and increasing portions of the U.S. population live in areas where Lyme is endemic, said Sam Telford, MS, SD, a professor of infectious diseases and global health at Tufts University, who helped develop the running the LYMErix clinical trials.
“Mothers are tired of 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 pick blueberries, let their kids play in the yard without worrying about them kicking a ball into the edge of the yard, that diminishes from the enjoyment of their home and community.”
About 85% of Lyme cases in the US occur between Memorial Day and the end of July, when poppy seed-sized young ticks can go unnoticed. If an infected burrowing tick goes undetected for more than a day, its saliva can enter its host’s bloodstream and pass on 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 produce antibodies that can attack the true pathogen, should it ever enter the body.
A group of researchers at MassBiologics takes a different approach: a prophylaxis injection 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 person is protected with Lyme PrEP, as the product is now called, the tick will also receive some antibodies. These neutralize an important protein on the outside Borrelia burgdorferithe bacteria that causes the most cases of Lyme disease in the US. This keeps the bacteria trapped in the tick’s gut and out of the host’s bloodstream.
People who live in places where Lyme is endemic can receive a dose that will protect them during 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 on deployment, a one-time small dose of PrEP injection can be much more temporary, staying in their system for only a few weeks or a month.
“Depending on the dose, we think your protection can be adjusted for a month or two months, if that’s all you wanted or needed, 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 run out.’ And you can do that kind of thing with a monoclonal antibody.”
The Lyme bacteria is a weak antigen, making 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 that people who get Lyme PrEP are likely to be protected, regardless of the strength of their immune system, Klempner said.
In addition, 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 side effects of Lyme PrEP have been some pain at the injection site.
Lyme PrEP has so far only been tested in a phase 1 clinical trial. Future studies will test the duration of protection and other important safety and efficacy measures. Klempner said his team plans to conduct a Phase 3 clinical trial next summer and seek FDA approval in 2025.
A more traditional vaccine could be available next summer
The vaccine closest to the finish line is being developed by Pfizer and Valneva. VLA15, as it is called, is a three-dose vaccine that trains the immune system to make antibodies that Borrelia in the gut of the tick, just like Lyme PrEP does.
According to the companies, phase 2 clinical trials showed the vaccine was safe in people as young as 5 years old and provided protection for more than six months. In February, the companies announced that the phase 3 trial has been delayed because they had to drop half of the study participants due to concerns unrelated to safety.
Both VLA15 and Lyme PrEP target the same thing 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 studies early on and included children in their studies.
In addition, the general interest in protection against Lyme disease appears to be high. A 2022 survey found that nearly two-thirds of respondents were willing to get a Lyme disease vaccine, while 7% were completely 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 will still be some activism against the vaccine.”
For people skeptical of a traditional vaccine, Lyme PrEP could be more appealing.
“There are many benefits to having choices,” Telford said. Everyone has their own perception of risk and their own perception of what they think they need. Having more than one option will be great for everyone.”
Other ways to prevent tick-borne diseases
While Lyme is the most common tick-borne disease, 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 US can carry pathogens that cause 16 diseases, including Powassan virus disease, ehrlichiosis and babesiosis. Anti-Lyme vaccines do not protect against these other diseases.
“People should familiarize themselves with the types of ticks that live in their area and make sure they take preventative measures for themselves, their children and their pets,” Connally told Verywell in an email. “We recommend bathing after outdoor activities, performing daily tick checks, and using a tick prevention product on ticks year-round.”
Wearing long pants, long-sleeved shirts, and other protective clothing makes it more difficult for ticks to attach to your skin. Wearing socks and pants treated with permethrin or other EPA-registered insect repellents can repel ticks. Raking leaves and removing excess vegetation can make a garden less habitable for ticks.
Just as most people automatically reach for a helmet before getting on a bike, or strapping themselves into their seats, they should also reach for insect repellent to protect against ticks and other insect-borne infections, Telford said.
“Yes, it is unpleasant to be bitten by a tick. Yes, it’s terrible to get sick from a tick bite,” Telford said. “However, people should not be afraid to go outside. It is good for your health to be outside and 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 daily for ticks. Remove the tick immediately, then shower and watch for signs of fever or other Lyme disease symptoms.