A phase 3 trial of an investigational Lyme disease vaccine from Pfizer Inc. and Valneva SE demonstrated more than 70% efficacy, signaling potential progress toward the first approved human vaccine for the disease. Pfizer is planning to move forward with regulatory submissions for potential approval.
Pfizer and Valneva have announced topline results from their phase 3 VALOR trial evaluating PF-07307405 (also known as LB6V, formerly VLA15), an investigational Lyme disease vaccine candidate. The study showed that the vaccine achieved efficacy rates exceeding 70% in preventing confirmed cases of Lyme disease during the second season following vaccination.1 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, senior vice president and chief vaccines officer at Pfizer, said in a statement. “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.”1
Specifically, the vaccine demonstrated 73.2% efficacy starting 28 days after the fourth dose and 74.8% efficacy beginning just one day after the fourth dose, compared to placebo. These findings highlight the vaccine’s ability to significantly reduce infection risk in individuals living in or traveling to high-incidence areas.1
Although the trial did not meet its primary statistical endpoint—due to fewer-than-expected Lyme disease cases during the study period—the companies emphasized that the results remain clinically meaningful. Notably, one of the pre-specified analyses met the required confidence interval threshold, reinforcing confidence in the vaccine’s protective potential.1
The VALOR trial enrolled participants aged 5 years and older across multiple sites in the United States, Canada, and Europe. Participants received a four-dose regimen, including an initial series and a booster timed ahead of peak Lyme disease season.1
PF-07307405 is a multivalent protein subunit vaccine designed to target outer surface protein A (OspA) of Borrelia burgdorferi, the bacterium responsible for Lyme disease. By generating antibodies that act within the tick during feeding, the vaccine aims to block transmission before infection occurs—a novel preventive approach.1
Currently, there are no approved vaccines for Lyme disease in humans, making this candidate one of the most advanced in development. Based on these results, Pfizer plans to move forward with regulatory submissions, potentially bringing the first Lyme vaccine closer to market.1
The vaccine candidate achieved over 70% efficacy in preventing Lyme disease in a large Phase 3 trial.
Despite missing the primary endpoint, secondary analyses support strong clinical potential.
If approved, PF-07307405 could become the first human vaccine available to prevent Lyme disease.
It is considered the most common vector-borne illness in the Northern Hemisphere.2,3 The Centers for Disease Control and Prevention (CDC) has estimated that approximately 476,000 people in the US are diagnosed and treated each year and 132,000 cases are reported annually in Europe from countries with surveillance systems.4
Early symptoms of Lyme disease (such as a gradually expanding erythematous rash called erythema migrans or other nonspecific symptoms like fatigue, fever, headache, mild stiff neck, muscle and joint pains) are often overlooked or misinterpreted. Left untreated, the disease can disseminate and cause more serious chronic complications affecting the skin, joints (arthritis), the heart (carditis) or the nervous system.4,5
