Pfizer and Valneva's Lyme Disease Vaccine Shows 73% Efficacy in Phase 3 Trial
Key Insights
Pfizer and Valneva (search)'s investigational Lyme disease (search) vaccine candidate PF-07307405 demonstrated over 70% efficacy in preventing Lyme disease in individuals aged five years and above in the Phase 3 VALOR trial.
The vaccine showed 73.2% efficacy from 28 days post-dose 4 and 74.8% efficacy from 1-day post-dose 4 in reducing confirmed Lyme disease (search) cases compared to placebo.
The investigational vaccine was well tolerated with no safety concerns identified at the time of analysis, strengthening confidence for regulatory submissions.
Pfizer Inc. and Valneva (search) SE announced topline results from their Phase 3 VALOR clinical trial showing their investigational Lyme disease (search) vaccine candidate PF-07307405 (LB6V (search)) demonstrated more than 70% efficacy in preventing Lyme disease in individuals aged five years and above. The vaccine candidate was well tolerated with no safety concerns identified at the time of analysis.
Strong Efficacy Results in Pivotal Trial
The Phase 3 VALOR "Vaccine Against Lyme for Outdoor Recreationists" trial (NCT05477524) met its primary endpoints with impressive efficacy results. In pre-specified analyses, the vaccine demonstrated:
- 73.2% efficacy from 28 days post-dose 4 (season 2) in reducing the rate of confirmed Lyme disease cases compared to the placebo arm (95% CI 15.8, 93.5)
- 74.8% efficacy from 1-day post-dose 4 (season 2) in reducing the rate of confirmed Lyme disease cases compared to the placebo arm (95% CI 21.7, 93.9)
The VALOR trial was conducted as a multicenter, placebo-controlled, randomized, observer-blinded study at sites in areas of high Lyme disease (search) incidence across the United States, Canada, and Europe. Trial participants aged 5 years and older were randomized 1:1 into two groups and received four doses of either PF-07307405 or saline placebo, administered at months 0, 2, 5-9, followed by a fourth dose one year later before the start of the following Lyme disease season.
Novel Vaccine Mechanism Targets Tick Transmission
PF-07307405 represents the most advanced Lyme disease (search) vaccine candidate in clinical development, having completed two pivotal Phase 3 trials. Currently, no approved human vaccines exist for Lyme disease. This investigational multivalent protein subunit vaccine employs an established mechanism targeting the outer surface protein A (OspA (search)) of Borrelia burgdorferi (search), the bacteria causing Lyme disease.
The vaccine's unique approach works by generating antibodies against six Borrelia OspA (search) serotypes in immunized individuals. When an infected tick feeds on a vaccinated person, these antibodies are ingested as part of the tick's blood meal. The vaccine-induced antibodies then bind to OspA on Borrelia inside the tick, inhibiting the bacterium's ability to leave the tick and preventing transmission to the human host. The vaccine candidate covers the six most prevalent OspA serotypes expressed by Borrelia burgdorferi (search) sensu lato species in North America and Europe.
Addressing a Growing Public Health Challenge
Lyme disease (search) represents a significant and expanding public health concern. The systemic infection is caused by Borrelia burgdorferi (search) sensu lato bacteria transmitted through bites from infected Ixodes ticks. It is considered the most common vector-borne illness in the Northern Hemisphere.
The Centers for Disease Control and Prevention estimates that approximately 476,000 people in the United States are diagnosed and treated annually, with 132,000 cases reported each year in Europe from countries with surveillance systems. Early symptoms, including gradually expanding erythematous rash (erythema migrans) and nonspecific symptoms like fatigue, fever, headache, mild stiff neck, and muscle and joint pains, are often overlooked or misinterpreted.
Left untreated, Lyme disease (search) can disseminate and cause serious chronic complications affecting the skin, joints (arthritis), heart (carditis), or nervous system. The medical need for vaccination against Lyme disease continues to increase as the geographic footprint of the disease expands.
Regulatory Path Forward
Based on these positive results, Pfizer is planning submissions to regulatory authorities. The strong efficacy and safety profile demonstrated in the VALOR trial strengthens confidence in the vaccine candidate's potential to address the significant unmet medical need in Lyme disease (search) prevention.