Pfizer and Valneva are making strides in their Lyme disease vaccine program, achieving a significant milestone by demonstrating the safety and effectiveness of booster doses in adolescents and younger children during a phase 2 clinical trial.
This journey began in 2020 when Pfizer acquired the rights to the multivalent protein subunit vaccine VLA15 for an upfront payment of $130 million. Collaborating with Valneva, they have steadily advanced the candidate through a series of data releases involving both adults and children. Their initial phase 2 data, focusing on individuals aged 5 to 17 years, was released last year, prompting them to expand their pivotal study to include children. Now, they have unveiled updated results.
The latest data focuses on the response of participants who received booster shots as part of the phase 2 trial. During this trial, participants underwent a primary vaccination course with either two or three doses over six months, followed by a booster shot or a placebo in Month 18.
Following the booster doses, participants developed antibodies against Lyme disease proteins. The seroconversion rate for all outer surface protein A serotypes in all age groups ranged from 94.6% to 95.3%, depending on whether a two- or three-dose primary course was administered. Importantly, antibody titers were significantly higher after the booster shot compared to those following the primary schedule. One month after the booster, Pfizer and Valneva observed a 2.0- to 2.7-fold increase in antibody titers, though this was slightly lower than the 3.3- to 3.7-fold increase observed in adults. Notably, the safety and tolerability profile remained consistent with earlier studies.
The phase 2 clinical trial is ongoing, with Pfizer and Valneva planning to administer another booster shot or a placebo at Month 30 to assess the necessity of continued dosing. However, the ultimate test for this vaccine candidate will come from a phase 3 trial that Pfizer and Valneva are conducting to support regulatory approvals on both sides of the Atlantic.
“We are pleased with these data which validate the use of a booster dose in all age groups. Lyme disease continues to spread, representing an important unmet medical need that impacts the lives of many people in the Northern Hemisphere. With each new set of positive data, we come one step closer to potentially bringing this vaccine to both adults and children living in areas where Lyme disease is endemic.”
– Juan Carlos Jaramillo M.D., Chief Medical Officer of Valneva
This phase 3 study encountered a setback earlier this year when compliance issues at certain study sites necessitated the removal of approximately half of the trial’s participants. As a result, the trial faced a one-year delay, pushing the anticipated data for regulatory approval from 2025 to 2026. Despite this setback, Pfizer and Valneva remain committed to advancing this vital Lyme disease vaccine candidate through rigorous testing and development.
