Pfizer Lyme Disease Vaccine Seeks Approval
Pfizer Lyme disease vaccine showed strong late-stage efficacy; companies plan submissions despite missing the primary endpoint, creating investor risk.
KEY TAKEAWAYS
- VALOR pre-specified analysis showed 73.2% efficacy 28 days after the fourth dose in season two.
- Primary endpoint missed because fewer-than-anticipated Lyme cases accrued and CI lower bound fell below 20%.
- Pfizer and Valneva will seek regulatory submissions citing the second analysis that met the CI threshold.
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Pfizer Inc. and Valneva SE said on March 23, 2026, that their Lyme disease vaccine candidate showed over 70% efficacy in a Phase 3 trial. Despite missing the study’s primary endpoint, the companies plan to seek regulatory approval.
VALOR Trial Results
The multicenter VALOR trial (NCT05477524) tested PF-07307405 (LB6V, formerly VLA15) in a placebo-controlled, randomized, observer-blinded study. It enrolled 9,437 participants aged 5 and older at high-incidence sites in the U.S., Canada, and Europe. The vaccine was administered in four doses over two seasons (months 0, 2, and 5–9).
A pre-specified analysis showed 73.2% efficacy 28 days after the fourth dose in the second season, with a 95% confidence interval (CI) of 15.8–93.5. A second pre-specified analysis found 74.8% efficacy one day after the fourth dose in season two, with a 95% CI of 21.7–93.9. The companies said the primary endpoint was not met because fewer Lyme disease cases than expected accrued, leaving the lower bound of the first analysis’s confidence interval below the trial’s 20% threshold.
Regulatory Plans and Program Context
The companies reported the vaccine was well tolerated with no safety concerns. Pfizer and Valneva said they will pursue regulatory submissions based on the clinically meaningful efficacy and the second analysis meeting the confidence-interval threshold. The releases did not specify filing dates or conditions.
The program began under an April 2020 collaboration granting Pfizer exclusive commercialization rights after approval. A 2023 Good Clinical Practice finding at some U.S. sites led about half of U.S. participants to discontinue, delaying a planned filing by roughly one year. No vaccines for Lyme disease are currently approved.
Annaliesa Anderson, Pfizer’s senior vice president and chief vaccines officer, said, “The efficacy shown in the VALOR study of more than 70% is highly encouraging and creates confidence in the vaccine’s potential to protect against this disease that can be debilitating.”
