Valneva SE (VALN) and Pfizer Inc. (PFE) have released positive immunogenicity and safety data from their Phase 2 study of VLA15, a Lyme disease vaccine candidate. The study investigated the effects of a second booster dose given one year after the first booster.
The results showed that one month after receiving the second booster, the immune response and safety profile of VLA15 were similar to those observed after the first booster. This indicates that the second booster is compatible with the anticipated benefits of a booster vaccination before each Lyme season.
Notably, a high proportion of participants achieved seroconversion after the second booster dose. Seroconversion occurs when the body develops antibodies in response to an infection or immunization. Seroconversion rates (SCRs) exceeded 90% for all outer surface protein A (OspA) serotypes across all age groups, mirroring the SCRs observed after the first booster. Geometric Mean Titers were also comparably high one month after both the first and second booster doses.
In August 2022, Pfizer and Valneva initiated the ongoing Phase 3 VALOR study to investigate the efficacy, safety, and immunogenicity of VLA15 in participants aged five years and older residing in highly endemic regions in the U.S. and Europe. The primary vaccination series for all participants in this study was completed in July 2024. A second Phase 3 study (VLA15-1012) is also underway to gather further evidence on the safety profile of VLA15 in the pediatric population.
Pfizer plans to submit marketing applications to the FDA and the European Medicines Agency (EMA) in 2026, contingent upon positive results from the ongoing Phase 3 trials. Currently, there are no approved human vaccines for Lyme disease, and VLA15 represents the most advanced vaccine candidate in clinical development, with two Phase 3 trials underway.
The Centers for Disease Control and Prevention (CDC) estimates that approximately 476,000 people in the U.S. are diagnosed and treated for Lyme disease each year. In Europe, an estimated 129,000 cases are reported annually.
The news of these positive results has led to some movement in the stock prices of both companies. VALN stock is down 0.27% at $7.30, and PFE stock is down 2.13% at $28.40.
