October 24, 2026
2 min read
Key takeaways:
- A researcher said the vaccine has been developed “to fill the gap.”
- However, the drug “just missed” the trial’s primary endpoint.
WASHINGTON — A phase 3 clinical trial revealed that the investigational vaccine candidate — known as LB6V — showed more than 70% efficacy against confirmed Lyme disease, according to results presented at IDWeek.
But, in the end, the drug failed to hit its primary endpoint.
Data derived from Auwaerter PG, et al. Efficacy and safety of the LB6V Lyme disease vaccine candidate: Results from a phase 3 study in participants ≥5 years of age. Presented at: IDWeek; Oct. 21-24, 2026; Washington.
LB6V has a “clinically meaningful” efficacy, researcher Paul G. Auwaerter, MD, clinical director of the division of infectious diseases and professor of medicine at Johns Hopkins University School of Medicine, said during the presentation.
The vaccine, co-funded by Pfizer and Valneva, demonstrated 73.2% (95% CI, 15.8%-93.5%) efficacy 28 days after the fourth and final dose vs. placebo, according to the trial. Additionally, the drug was 74.8% efficacious starting 1 day after the fourth dose.
But the endpoint, Auwaerter noted, “just missed” with the lower bound of the 95% CI falling below the required 20% threshold. Auwaerter attributed the miss on a limited number of cases.
The multicenter, randomized, placebo-controlled, observer-blinded trial enrolled nearly 10,000 participants aged 5 years and older of which 8,011 completed the trial.
Participants received four doses of the six-valent OspA-based Lyme disease vaccine or a saline placebo. Researchers administered doses at 0 months, 2 months and between 5 and 9 months, with a final dose 1 year later.
“I believe that LB6V is safe and has a favorable side-effect profile,” Auwaerter said.
Lyme disease, which is the most reported vector-borne disease in the country, is spread by blacklegged (Ixodes) ticks carrying Borrelia burgdorferi bacteria. Untreated, it can produce a wide range of symptoms, including fever, rash, facial paralysis, an irregular heartbeat and arthritis, according to the CDC. More than 80,000 cases of Lyme disease are reported each year to the CDC. The actual number of cases that occur annually is much higher — estimated to be around 476,000.
Auwaerter pointed out that LB6V protects against the six most common serotypes of B. burgdorferi in the U.S. and Europe.
“Unfortunately, there is not a commercial vaccine currently available to prevent Lyme disease. So, to fill the gap, LB6V was developed,” he said.
The only Lyme disease vaccine approved in the U.S., LYMErix, debuted in 1998 but was discontinued by GSK in 2002 after reports of acute side effects — later proven inaccurate — led to poor sales.
LB6V’s trial results were first announced back in March, with Pfizer saying it would pursue regulatory approval. And last year, Valneva said it expected Pfizer to launch the vaccine in U.S. and European markets in the second half of 2027, pending approval.
Auwaerter did not mention the drug’s potential approval or launch during his presentation.
Perspective
This is the same vaccine and the same results that were reported earlier this year. They presented a little more data this time. The results are encouraging, but they did not address efficacy in year one. And how eager will people be to get a vaccine for which they need to wait 18 months for it to be effective?
Eugene Shapiro, MD
Editorial Board Member, Healio | Infectious Disease News Yale School of Public Health
Disclosures: Shapiro reports receiving royalties from UptoDate and has testified in the past as an expert witness.
Sources/Disclosures
Source:
Auwaerter PG, et al. Efficacy and safety of the LB6V Lyme disease vaccine candidate: Results from a phase 3 study in participants ≥5 years of age. Presented at: IDWeek; Oct. 21-24, 2026; Washington.
References:
Disclosures:
Auwaerter reports being a board member for the American Lyme Disease Foundation, receiving grant/research support from Pfizer and being an advisor/consultant for Tarsus Pharmaceuticals.
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