Valneva SE (NASDAQ:VALN) saw its stock move higher on Wednesday after the company released final Phase II results for its Lyme disease vaccine candidate, VLA15, showing robust immune responses following a third annual booster shot.

According to the data, participants across all age groups—children, adolescents, and adults—mounted strong anamnestic antibody responses to all six serotypes targeted by the vaccine. After the booster given at month 42, antibody levels climbed rapidly and stayed well above initial levels through month 48, suggesting the vaccine could offer year-to-year protection against Lyme disease.

The study also found that the three-dose primary regimen produced substantially higher antibody levels than the two-dose schedule. Geometric mean fold rises ranged from 9.5-fold for Serotype 1 to 15.6-fold for Serotype 2, with the most pronounced responses seen in children aged 5 to 11, where increases reached up to 28.5-fold.

Safety results remained positive, with no issues flagged by the independent Data Monitoring Committee.

VLA15—developed in partnership with Pfizer (NYSE:PFE)—is currently the most advanced Lyme disease vaccine candidate in clinical development, at a time when no approved human vaccines for the disease exist. Two Phase III trials are nearing completion, and the companies plan to submit regulatory applications to both the FDA and EMA in 2026 if the results remain favorable.

“We view the phase III readout expected in H1 2026 as one of the most compelling risk/reward catalysts in the European biotech space over the next six months,” noted Stifel analysts.

Valneva stock price

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