Pfizer/Valneva Aim for FDA Approval of mRNA Shot for Lyme Disease

On Mar. 23, 2026, Pfizer, Inc. of New York City, NY and Valneva SE of Saint-Herblain, France announced that they would seek regulatory approval from the U.S. Food and Drug Administration (FDA) for an experimental mRNA (messenger ribonucleic acid) biologic shot against Lyme disease that they have jointly been developing since 2020. The shot, designated PF-07307405 (LB6V), formerly VLA15, is designed to target six serotypes of the tick-borne bacteria Borrellia burgdorferi found in North America and Europe.^{1 2 3 4 5}

According to Pfizer, the shot demonstrated a “clinically meaningful” efficacy rate in a Phase 3 randomized controlled clinical trial, reducing the rate of infection by more than 70 percent in people who received the shot versus those given a placebo.^{1 5}

In the trial (NCT05477524), known as “VALOR” (Vaccine Against Lyme for Outdoor Recreationists), participants five years of age and older were randomized 1:1 into two groups and given four doses of either PF-07307405 or a saline placebo. The first dose was followed by a second dose at two months, a third dose 5-9 months after that, and a fourth dose one year later, just prior to the time of the year Lyme disease is most prevalent.⁵

Shot Falls Short of Efficacy Expectations

The 70-73 percent efficacy rate attained by PF-07307405 fell short of Pfizer/Valneva’s expectations of 95 percent. Part of the reason given for the markedly lower rate was that “fewer than anticipated Lyme disease cases were accrued over the study period.” Another reason, however, may have been that nearly half of the 18,000 participants enrolled in the Phase 3 clinical trials for PF-07307405 were “removed following Good Clinical Practice (GCP) violations in February 2023,” as reported in an article in a 2023 edition of The Vaccine Reaction.^{1 5} The article noted:

While [Pfizer and Valneva] did not disclose which GCP violations occurred, some of the most common GCP violations in pharmaceutical clinical trials include protocol adherence; confirming clinical records warrant study participants’ involvement; informed consent; safe drug handling and storage conditions, and expeditious adverse event reporting. In a Feb. 17, 2023 press release, Pfizer and Valneva attributed the GCP violations to a third-party clinical trial site operator.⁶

The “third-party” clinical site operator was a clinical research company called Care Access. Care Access denied the claims of quality violations. It said that it disagreed with Pfizer’s decision to discontinue thousands of study participants and its basis, and that it would be sharing information with the FDA and the independent Institutional Review Board “to ensure they have the facts.”^{3 7}

If approved for licensure by the FDA, PF-07307405 is projected to generate peak annual sales of $1 billion for Pfizer and Valneva.³

No Lyme Disease Vaccines on the Market

Currently, there are no human vaccines for Lyme disease in the United States. A previous vaccine for Lyme called LYMErix, produced by GSK of the United Kingdom, was approved in 1998 but discontinued in 2002 following a class-action lawsuit alleging that it harmed hundreds of people who got the shot. More than 900 reports of symptoms ranging from swollen joints, a aching muscles and extreme fatigue to more serious rheumatologic, neurologic, and autoimmune adverse effects were cited.⁶

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