Pfizer and Valneva Advance Lyme Disease Vaccine Candidate to Regulatory Review
Pharmaceutical giants Pfizer and Valneva announced on Monday, March 23, 2026, that they plan to seek regulatory approval for their Lyme disease vaccine candidate, VLA15, following the completion of the Phase 3 VALOR trial. This marks a significant step toward potentially providing a new preventative measure against the increasingly prevalent vector-borne disease.
The VALOR Trial and VLA15 Development
The Phase 3 VALOR (Vaccine Against Lyme for Outdoor Recreationists) trial, a placebo-controlled study, investigated the efficacy, safety, and immunogenicity of VLA15 in participants aged five years and older. Approximately 9,437 participants were enrolled across the U.S., Europe, and Canada, in areas where Lyme disease is endemic. Pfizer and Valneva jointly announced the completion of the primary vaccination series – three doses – in July 2024. Participants are being monitored for Lyme disease cases through the end of the 2025 Lyme disease season.
VLA15 is a multivalent recombinant protein vaccine targeting six serotypes of the Borrelia bacteria, representing the most common pathogenic strains found in North America and Europe. Valneva notes that VLA15 is currently the only Lyme disease vaccine candidate in clinical development.
Positive Phase 2 Results and Booster Data
Data from Phase 2 studies have demonstrated strong immunogenicity in both adults and children, with acceptable safety and tolerability profiles. Results from Phase 2 trials were published in The Lancet Infectious Diseases. In November 2025, Valneva reported positive final immunogenicity and safety data six months after a third booster dose, confirming the potential benefits of yearly vaccination prior to each Lyme season.
Pfizer and Valneva initially entered into a collaboration agreement in April 2020 to co-develop VLA15, with updates to the terms in June 2022.
Lyme Disease Burden and Unmet Need
Lyme disease is the most prevalent vector-borne disease in the United States and Europe. According to the U.S. Centers for Disease Control and Prevention (CDC), approximately 476,000 Americans are diagnosed and treated for Lyme disease each year, with at least another 130,000 cases occurring in Europe. The disease can lead to debilitating complications and require extensive healthcare treatment. The lack of effective current interventions underscores the urgent need for preventative measures like the VLA15 vaccine.
Looking Ahead
With the completion of the Phase 3 VALOR trial, Pfizer and Valneva are preparing to submit data to regulatory authorities for potential approval. If approved, VLA15 could offer a crucial new tool in the fight against Lyme disease, protecting individuals at risk of exposure through tick bites.