Pfizer and French partner to seek approval for Lyme disease vaccine after late-stage trial

By Steve GoldsteinJaimy Lee

Valneva shares slump after the companies said the study's primary endpoint didn't meet statistical significance

Pfizer and Valneva plan to seek regulatory approval for a Lyme disease vaccine.

Pharmaceutical giant Pfizer and French partner Valneva said they plan to seek regulatory approval for a Lyme disease vaccine after sharing mixed results from a late-stage trial.

The companies said Monday that a Phase 3 study of their Lyme disease vaccine candidate demonstrated more than 73% efficacy in preventing Lyme disease in people 5 years old and older. However, the vaccine didn't meet the predetermined statistical criterion in the primary endpoint, in part because there were fewer cases of Lyme than had been expected.

The vaccine was well-tolerated, with no safety concerns. The study's participants received four doses of the experimental vaccine or placebo in regions with high rates of Lyme.

Pfizer said it would still seek approval, given the "clinically meaningful efficacy." It added that a second prespecified analysis was statistically significant. There are no vaccines or therapies that can prevent Lyme disease on the market, though GSK briefly sold a Lyme vaccine starting in the 1990s until 2002, when the British drugmaker pulled the shot "due to weak demand and public concerns about adverse events," according to RBC Capital Markets' Trung Huynh.

Huynh believes that there will be support in Washington, D.C., for the vaccine, noting that Health and Human Services Secretary Robert F. Kennedy Jr. has called for better prevention and treatment of Lyme disease. The analyst expects peak sales of $525 million.

Shares of Pfizer (PFE), up 8% this year, eased 1% in premarket trading.

Valneva's stock (FR:VLA) (VALN) slumped 35% in Paris trading.

Under the terms of their agreement, Valneva is due tiered royalties of up to 22% and milestone payments from Pfizer of up to $100 million.

Pfizer owns 5.6% of Valneva, according to FactSet data.

-Steve Goldstein -Jaimy Lee

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03-23-26 0945ET