Pfizer-Valneva Lyme Vaccine Misses Phase 3 Threshold — But Both Companies Are Pressing Forward

By FieldPulse Staff · March 23, 2026

Tags: vaccines, pfizer, phase-3, fda

The VALOR trial met its primary endpoint numerically but fell below the pre-specified statistical confidence interval, largely due to lower-than-expected Lyme disease case rates in the study population. Pfizer and Valneva say they still plan to pursue regulatory submissions.

Pfizer and Valneva announced Phase 3 results on March 23, 2026 for their Lyme disease vaccine candidate PF-07307405, a six-valent OspA-based vaccine.

The data tell an unusual story: the vaccine worked — just not well enough to clear the pre-specified statistical bar, and for reasons largely outside the drug's control.

The VALOR trial demonstrated 73.2% efficacy from 28 days after the fourth dose, and 74.8% from one day post-dose four.

But the lower bound of the 95% confidence interval on the primary endpoint came in at 15.8%, below the pre-specified 20% threshold.

The shortfall wasn't a safety signal — no safety concerns were identified.

The problem was epidemiological: fewer confirmed Lyme disease cases occurred in the study population than the trial was powered to detect.

There is currently no approved Lyme disease vaccine on the U.S.

market.

The only prior candidate, LYMErix (SmithKline Beecham), was withdrawn in 2002 following controversy over alleged side effects that were never confirmed.

Roughly 476,000 Americans are diagnosed with Lyme disease annually, according to CDC estimates.

Valneva's stock dropped more than 38% on the news.

Pfizer's shares moved modestly.

Despite the miss, both companies have said they intend to submit regulatory applications and let the FDA weigh the totality of the evidence.

What it means for reps: The regulatory path for this vaccine is now uncertain.

FDA will have to decide whether 73% efficacy with a failed confidence interval threshold is sufficient for approval — a judgment call with no clean precedent.

Primary care and pediatric reps should watch closely: if approved, this would be a significant vaccine launch in a population with 300,000+ new U.S.

diagnoses annually.

If FDA declines, the Lyme vaccine space remains empty.

Source: https://www.biopharmadive.com/news/pfizer-valneva-lyme-disease-vaccine-study-results/815395/