Lyme Disease Vaccine Candidate Shows Promise as Tick-Borne Risk Persists in the US

As Lyme disease incidence continues to rise across the US, an investigational vaccine candidate, VLA15 (Pfizer Inc, Valneva SE), is showing promise in late-stage development. Pfizer and Valneva recently announced ongoing progress in their phase 3 VALOR clinical trial (NCT05477524) evaluating the safety, tolerability, and immunogenicity of the vaccine, which targets Borrelia burgdorferi, the bacterium responsible for Lyme disease.^1,2

Lyme disease remains the most common vector-borne illness in the US, with approximately 476,000 Americans diagnosed and treated annually, according to the CDC. The burden is especially pronounced in the Northeast, mid-Atlantic, and upper Midwest regions, where blacklegged ticks (Ixodes scapularis) are endemic.³

“Lyme disease can cause potentially serious consequences—where individuals and families face symptoms that can disrupt daily life, work, and long-term health—and there is currently no vaccine available,” Annaliesa Anderson, PhD, senior vice president and chief vaccines officer at Pfizer, said in a news release.¹

Vaccine Development and Clinical Progress

VLA15 is a multivalent protein subunit vaccine designed to protect against 6 serotypes of B burgdorferi. Unlike prior Lyme vaccine efforts, VLA15 specifically targets outer surface protein A, aiming to block transmission of the bacterium from tick to human.¹

Earlier phase 2 data demonstrated strong immunogenicity across different age groups, including children and older adults, with a favorable safety profile. The ongoing VALOR trial is expected to further assess efficacy in a large population living in endemic areas. If successful, VLA15 could become the first Lyme disease vaccine available for humans in over 2 decades.⁴

“The efficacy shown in the VALOR study of more than 70% is highly encouraging and creates confidence in the vaccine’s potential to protect against this disease that can be debilitating,” Anderson emphasized.¹

Tick Infection Rates Underscore Need for Prevention

The urgency of vaccine development is underscored by the high prevalence of B burgdorferi in ticks. In endemic regions of the Northeast, studies estimate that approximately 20% to 50% of blacklegged ticks are infected with Lyme disease–causing bacteria. This substantial reservoir contributes to ongoing transmission risk, particularly during warmer months when tick activity peaks.⁵

Environmental factors, including climate change and expanding tick habitats, have further increased human exposure. As a result, Lyme disease cases have steadily risen, with geographic spread extending into previously lower-risk areas.³

Implications for Pharmacists and Public Health

For pharmacists, the potential introduction of a Lyme disease vaccine represents a meaningful advancement in preventive care. Pharmacists are well-positioned to educate patients about tick-borne disease prevention, recognize early symptoms of Lyme disease, and, if approved, administer the vaccine in community settings.

Early Lyme disease is typically treated effectively with antibiotics; however, delayed diagnosis can lead to more severe complications, including neurologic and cardiac manifestations. A preventive vaccine could significantly reduce the clinical burden and health care costs associated with advanced disease.³

Looking Ahead

Although VLA15 is still under investigation, its development marks a critical step forward in addressing a growing public health threat. With high tick infection rates and increasing disease incidence, a safe and effective Lyme disease vaccine could play a pivotal role in reducing transmission and improving patient outcomes.

“These results bring us a step closer to our goal of delivering a much-needed vaccine to help protect against Lyme disease. We are grateful to our partner Pfizer for their strong commitment, which we both share, to developing this vaccine as quickly as possible,” Thomas Lingelbach, CEO and board member of Valneva, concluded.¹

REFERENCES

1. Pfizer and Valneva announce Lyme disease vaccine candidate demonstrates strong efficacy in phase 3 VALOR trial. News release. Pfizer. March 23, 2026. Accessed March 24, 2026. https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-valneva-announce-lyme-disease-vaccine-candidate

2. An efficacy, safety, tolerability, immunogenicity, and lot-consistency clinical trial of a 6-valent OspA-based Lyme disease vaccine (VLA15) (VALOR). ClinicalTrials.gov. Updated September 29, 2025. Accessed March 24, 2026. https://clinicaltrials.gov/study/NCT05477524

3. Lyme disease surveillance and data. CDC. March 13, 2025. Accessed March 24, 2026. https://www.cdc.gov/lyme/data-research/facts-stats/index.html

4. Valneva announces positive final phase 2 results for Lyme disease vaccine candidate. News release. Valneva. November 26, 2025. Accessed March 24, 2026. https://valneva.com/press-release/valneva-announces-positive-final-phase-2-results-for-lyme-disease-vaccine-candidate/

5. Eisen RJ, Eisen L. The blacklegged tick, Ixodes scapularis: an increasing public health concern. Trends Parasitol. 2018;34(4):295-309. doi:10.1016/j.pt.2017.12.006