Pfizer and Valneva’s New Lyme Vaccine Demonstrates Over 70% Efficacy in Landmark Phase 3 Trial

Pfizer and Valneva's LB6V vaccine candidate demonstrates over 70% efficacy in preventing Lyme disease. Learn about the Phase 3 results and the path to FDA approval.

By: AXL Media

Published: Apr 10, 2026, 10:02 AM EDT

Source: Information for this report was sourced from Scientific American

A Potential Breakthrough for Tick-Borne Illness

Following years of escalating infection rates, the medical community is eyeing a significant shift in the fight against Lyme disease. Pfizer and Valneva recently reported that their vaccine candidate, PF-07307405 (also known as LB6V), successfully met its primary efficacy goals in a large-scale Phase 3 study. The trial, titled VALOR (Vaccine Against Lyme for Outdoor Recreationists), included approximately 9,400 participants across high-incidence areas in the United States, Canada, and Europe. With nearly 476,000 estimated annual cases in the U.S. alone, an approved vaccine would offer the first pharmaceutical defense against Borrelia burgdorferi since the withdrawal of the previous vaccine, LYMErix, in 2002.

Innovative Mechanism Targets Bacteria Inside the Tick

LB6V utilizes a unique "transmission-blocking" approach that differs from most traditional vaccines. This multivalent protein subunit vaccine targets six common serotypes of the outer surface protein A (OspA) found on the bacteria. When a vaccinated person is bitten, the tick ingests antibodies along with the blood meal. These antibodies bind to the bacteria within the tick’s gut, preventing them from migrating to the tick’s salivary glands and entering the human host. By neutralizing the pathogen before it ever enters the human body, the vaccine aims to prevent infection at the source.

Phase 3 Trial Performance and Statistical Nuances

The topline data revealed an efficacy of 73.2% when measured 28 days after the fourth dose, and 74.8% when measured immediately after. Despite these strong numbers, the trial faced a complex statistical path; it initially fell short of its primary statistical goal in a first analysis due to a lower-than-expected number of infections in the placebo group. However, a second pre-specified analysis met the required criteria, providing Pfizer with the confidence to move forward with regulatory submissions. The company described the 70% reduction in infections as "clinically meaningful," especially given the debilitating long-term neurological and cardiac complications associated with untreated Lyme disease.