Pfizer-Valneva Lyme Disease Vaccine Shows 73% Efficacy in Phase 3 Trial, Stony Brook Researchers Report
Key Insights
A Phase 3 trial of the Pfizer-Valneva (search) Lyme disease (search) vaccine demonstrated approximately 73% effectiveness at reducing Lyme disease, with no unexpected side effects reported in preliminary data.
Stony Brook Children's Hospital served as a clinical trial site for the pediatric study; the Phase 3 trial is now completed, though peer-reviewed data have not yet been published.
Suffolk County, Long Island, has the highest density of tick-borne diseases in the United States, with Stony Brook Medicine (search) diagnosing 30 to 70 children with Lyme disease (search) per month.
A Lyme disease (search) vaccine developed by Pfizer and Valneva (search) has demonstrated approximately 73% efficacy in reducing Lyme disease in a completed Phase 3 clinical trial, according to preliminary results discussed by researchers at Stony Brook Medicine (search). The findings, released via press release but not yet published in a peer-reviewed journal, represent a potential milestone in the prevention of a disease that has reached endemic proportions on Long Island and across the northeastern United States.
Andrew Handel, MD, a board-certified Pediatric Infectious Disease specialist at Stony Brook Medicine (search), shared details of the vaccine's progress during a recent interview. "At Stony Brook Children's Hospital, we were a clinical trial site for the pediatric study," Handel said. "Recently some of the preliminary results came out on their Phase 3 trial—the largest trial generally done before going before the FDA. They found the vaccine was about 73 percent effective at reducing Lyme disease (search). From the preliminary data, there were no unexpected side effects."
Regulatory Path Forward
The Phase 3 clinical trial has been completed, but the full dataset has not yet undergone peer review. Handel emphasized the importance of scrutinizing the complete scientific record before drawing definitive conclusions. "My understanding is the Phase 3 clinical trial is completed; they just haven't published the actual data yet," he noted. "They released some findings through a press release, but the peer-reviewed paper has not yet been released. We are curious to see how it really looks once we have the actual scientific paper, and then it goes before the FDA, which reviews all the data submitted by the pharmaceutical company and can make a decision about whether to license it for use within the United States."
The Burden of Tick-Borne Disease on Long Island
Suffolk County, where Stony Brook Medicine (search) is located, carries the highest density of tick-borne diseases in the nation. Peter Igarashi, MD, dean of the Renaissance School of Medicine at Stony Brook University, underscored this reality at the institution's recent Symposium on Tick-borne Diseases: "Their work is especially important here on Long Island, where Suffolk County has the highest density of tick-borne diseases in the nation."
Handel quantified the ongoing pediatric burden: the number of children diagnosed with Lyme disease (search) through Stony Brook Medicine (search) over the past three years ranges from approximately 30 to 70 per month. "These numbers don't seem to be slowing down," Handel said. "We really need to think about tick-borne diseases in children as a separate entity. In pediatrics, we often see that children are not small adults, and even though the pathogens are the same, the manifestations and implications can be quite different in children."
Current Prevention and Treatment Landscape
In the absence of a licensed vaccine, current prevention strategies rely on tick avoidance and, in certain cases, antibiotic prophylaxis. Handel described the standard approach: "For prevention, we talk to people about avoiding tick bites altogether—different insect repellents, the importance of doing tick checks, all those preventive measures. Then for people who meet certain criteria we recommend a single dose of doxycycline, which has shown to be about 90 percent effective at preventing Lyme disease (search)."
For patients who develop Lyme disease (search), treatment follows Infectious Diseases Society of America (IDSA) guidelines, typically involving a course of doxycycline or amoxicillin depending on the patient's specific symptoms and case details. For those experiencing post-treatment Lyme disease syndrome—sometimes referred to as chronic Lyme—the focus shifts to symptom management. "The studies have demonstrated that prolonged antibiotic courses are not effective at reducing those symptoms," Handel explained. "For patients in those circumstances, we focus on symptom management."
Emerging Threats and Research Directions
The symposium, co-sponsored by the Stony Brook University Renaissance School of Medicine Departments of Medicine and Microbiology and Immunology on May 27, brought together leading researchers and clinicians to discuss the latest advances in tick-borne illness research and care. The day-long program addressed the growing prevalence of infections on Long Island as well as emerging threats, including the Bourbon virus (search) and alpha-gal syndrome (search).
Luis Marcos, MD, associate professor of clinical medicine in the Division of Infectious Diseases, discussed his research on post-treatment Lyme disease (search) syndrome, noting the cyclical nature of symptoms. "When I came here I started seeing patients coming in with symptoms like fatigue, headaches, neck stiffness, and joint pain after a positive test for Lyme disease," Marcos said. "Then the symptoms go away and something happens with them like a stress in life, a trauma, a long trip, or another infection, and all the symptoms come back again."
Charles Vorkas, MD, an infectious diseases physician-scientist, highlighted the gaps in understanding human immune responses to tick-borne infections. "We've learned a lot from mouse models, particularly how these pathogens get transmitted and the type of cells that they infect," Vorkas said. "However, in order to understand interventions that can help biomedical vaccination and immune-mediated interventions, we need to study them in clinically relevant models, such as individuals who present acute Lyme disease (search) or babesiosis (search)."
The symposium also recognized Congressman Nick LaLota, who represents Suffolk County, with Stony Brook Medicine (search)'s inaugural Healthcare Policy Leadership Award for his engagement on tick-borne disease issues. William Wertheim, MD, Executive Vice President of Stony Brook Medicine, emphasized that "the work that our researchers are doing is vital to improving the education, prevention, diagnosis and treatment of vector-borne disease."