New Lyme disease vaccine moves forward as experts warn of potential rise in tick bites and researchers consider gendered diagnostic differences

Clinical trial data from Pfizer and Valneva indicate that their new vaccine may reduce Lyme disease cases by around 70% when compared to a placebo. The makers aim to submit the data from their Phase 3 trials to regulatory agencies in the United States and Europe, advancing what could be the first new Lyme vaccine for humans in over two decades.

The only other such vaccine was pulled from the market in 2002 due to low consumer demand, according to the Center for Infectious Disease Research and Policy, which noted that a Lyme vaccine for dogs has been available for the past 10 years. This new shot for humans is known as LB6V and could help prevent bacterial infections, which are spread through bites from infected ticks.

"As the tick feeds on the vaccinated person, these antibodies are ingested by the tick as part of its blood meal," according to a press release describing outcomes of the latest LB6V trials. This then "[inhibits] the bacterium's ability to leave the tick, preventing it from being transmitted to the human host."

News of the trial results for LB6V comes as experts warn of a potentially bad tick season in the U.S., where hundreds of thousands of people may be diagnosed with the disease every year. 

While it will be some time before officials can assess the tick population size, spread, and related infections in 2026, the Centers for Disease Control and Prevention recently reported that weekly rates of emergency room visits for tick bites are currently higher than they've been since 2017 in most regions of the country. The Mayo Clinic reported in 2024 that confirmed cases rose by close to 70% — in part due to an updated definition of the tick-borne disease.  

Lyme disease is caused by the bacteria Borrelia burgdorferi and can be transmitted through bites from infected ticks. Research suggests that ticks able to carry the bacteria are spreading into new territory as a result of rising temperatures, while more are surviving milder winters. The disease has been found in North America, Europe, and parts of Asia.

In humans, symptoms generally include fever, headache, fatigue, and erythema migrans — or, a round "bull's-eye" skin rash. Untreated, the disease can progress to severely affect the joints, heart, and nervous system, so early diagnosis and care can be key.

Meanwhile, researchers at Johns Hopkins University School of Medicine found in a study published in Clinical and Experimental Medicine in February that "male and female patients with early Lyme disease present with different signs of the disease in the symptoms they report, their physical exams, and their laboratory test results," according to a news release. Male subjects were found to have "more obvious, severe disease" indicators in that early period.

"Males and females are different," John Aucott, study co-author and Director of the Johns Hopkins Lyme Disease Clinical Research Center, said in the release. "For both findings, the male group was more similar to females who had undergone menopause and more different from females who had not," with Aucott saying a closer look at hormone levels would be among the next steps in this research.

The co-authors underscored that further investigation is needed to understand how gendered differences — including potential biological and social-behavioral differences — may be impacting early diagnosis, treatment, and long-term well-being. The study adds to a growing body of knowledge suggesting that women may experience higher rates of delayed diagnosis, misdiagnosis, and coinfections while pursuing treatment for Lyme, with some researchers investigating medical gaslighting among women and people of color seeking care.

Down the line, access to an effective vaccine could prevent infection in the first place. 

In the meantime, experts suggest reducing the chances of a tick bite by wearing pants and long sleeves to cover skin whenever spending time outside where ticks may be active. Using a safe tick repellent, closely inspecting the skin for ticks, and safely removing any biting "attached" ticks are also recommended, as is seeking professional medical treatment — which may include a dose of antibiotics — in the case of a tick bite.

Kirsten Krueger contributed to the editing of this article.