New Lyme Disease Vaccine: What We Know

A new Lyme disease vaccine could help prevent not just infection, but some of the longer-term health effects that can follow.

In a large Phase 3 clinical trial, the vaccine developed by Pfizer and Valneva reduced Lyme disease cases by more than 70% in people ages 5 and older. The vaccine, known as VLA15 (PF-07307405), works by training the immune system to recognize a protein on the surface of the Lyme-causing bacteria.

When a tick bites a vaccinated person, these antibodies are taken up by the tick and can block the bacteria before it is transmitted into the body.

The study followed more than 12,000 participants across North America and Europe and used a series of doses timed before peak tick season. So far, the vaccine appears to be well tolerated, with no major safety concerns reported. 

You may have heard that Lyme disease can be hard to test for, especially early on, and that’s true in everyday medical care. To make the results more reliable, researchers didn’t rely on a single test. Instead, they looked at a combination of symptoms (such as the well-known bullseye rash or flu-like illness), lab results, and close follow-up over time. This allowed them to more accurately identify true cases of Lyme disease in both the vaccinated and placebo groups.

Infections like Lyme disease don’t just cause short-term illness; they can activate the immune system in ways that sometimes linger, affecting joints, the nervous system, or other parts of the body.

This is part of a larger pattern researchers are continuing to study: how infections can act as one piece of the puzzle in long-term immune system disruption.

A vaccine like this does not treat autoimmune disease, but it may help reduce one of the triggers that can set these processes in motion.

Citations

Pfizer Inc., & Valneva SE. (2026, March 23). Pfizer and Valneva announce Lyme disease vaccine candidate demonstrates strong efficacy in Phase 3 VALOR trial. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-valneva-announce-lyme-disease-vaccine-candidate

ClinicalTrials.gov. (2022). A Phase 3 trial to evaluate a Lyme disease vaccine (VLA15) (NCT05477524). U.S. National Library of Medicine. https://clinicaltrials.gov/study/NCT05477524