Valneva SE and Pfizer Inc. have announced positive immunogenicity and safety data from their VLA15-221 Phase 2 study, following a second booster vaccination of their Lyme disease vaccine candidate, VLA15. The study, which included pediatric and adult populations, demonstrated a robust immune response and a consistent safety profile, reinforcing the potential of VLA15 as a preventive measure against Lyme disease. With approximately 476,000 people in the U.S. diagnosed and treated for Lyme disease each year, and 129,000 cases reported annually in Europe, the need for an effective vaccine is significant.
The immune response and safety profile of VLA15 one month after receiving the second booster dose were similar to those reported after receiving the first booster dose, showing compatibility with the anticipated benefit of a booster vaccination prior to each Lyme season.
Immunogenicity Results
The VLA15-221 Phase 2 study demonstrated a significant anamnestic antibody response across all six serotypes covered by the vaccine candidate in pediatric (5 to 11 years of age), adolescent (12 to 17 years of age), and adult (18 to 65 years of age) participants. This was measured one month after the administration of the second booster dose (month 31). A high proportion of participants seroconverted after the second booster dose, yielding seroconversion rates above 90% for all outer surface protein A (OspA) serotypes in all age groups, consistent with seroconversion rates observed after the first booster. Geometric Mean Titers at one month post first and second booster (i.e. month 19 vs. month 31) were comparably high.
Participants in the Phase 2 study received VLA15 or placebo during the primary vaccination phase in two immunization schedules (month 0-2-6 or month 0-6), followed by a first booster dose at month 18 and a second booster dose at month 30.
Safety and Tolerability
The safety and tolerability profile of VLA15 after the second booster dose was comparable to that observed after the first booster. To date, no safety concerns have been observed by an independent Data Monitoring Committee (DMC) in any treatment or age group.
Ongoing Phase 3 Trials and Regulatory Submissions
In August 2022, Pfizer and Valneva initiated the Phase 3 clinical study, Vaccine Against Lyme for Outdoor Recreationists (VALOR) (NCT05477524), to assess the efficacy, safety, and immunogenicity of VLA15 in participants five years of age and older in highly endemic regions in the U.S. and Europe. The primary vaccination series for all participants was completed in July 2024. A second Phase 3 study (VLA15-1012) is also ongoing to provide further evidence on the safety profile of VLA15 in the pediatric population.
Pfizer aims to submit a Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) and a Marketing Authorization Application (MAA) to the European Medicines Agency (EMA) in 2026, contingent upon positive Phase 3 data.
About VLA15
VLA15 is an investigational multivalent protein subunit vaccine designed to target the outer surface protein A (OspA) of Borrelia burgdorferi, the bacteria responsible for Lyme disease. By blocking OspA, the vaccine aims to prevent the bacteria from leaving the tick and infecting humans. The vaccine candidate covers the six most prevalent OspA serotypes found in North America and Europe.
Clinical Significance
With the geographic footprint of Lyme disease widening, the medical need for a preventive vaccine is increasing. Current strategies rely on personal preventive behaviors, but a vaccine could significantly reduce the burden of acute and chronic complications associated with the disease. According to the CDC, early symptoms of Lyme disease, such as erythema migrans and nonspecific symptoms like fatigue and headache, are often overlooked, leading to more serious complications if left untreated.
