An investigational Lyme disease vaccine candidate demonstrated greater than 70% efficacy in preventing Lyme disease in a phase 3 randomized clinical trial, and Pfizer is planning submissions to regulatory authorities, according to a company press release.

Topline results from the VALOR trial showed that PF-07307405 reduced confirmed Lyme disease cases by 73% beginning 28 days after the fourth dose during the second Lyme disease season compared with placebo. A secondary analysis demonstrated approximately 75% efficacy beginning one day after the fourth dose. Although the pre-specified primary statistical criterion was not met due to fewer-than-anticipated cases, the companies reported clinically meaningful efficacy and expressed confidence in the vaccine’s potential.

The VALOR trial was a multicenter, randomized, placebo-controlled, observer-blinded phase 3 study conducted in the United States, Canada, and Europe in regions with high Lyme disease incidence. Participants aged 5 years and older were randomized in a 1:1 ratio to receive three primary doses of PF-07307405 or saline placebo at months 0, 2, and 5 to 9, followed by a fourth (booster) dose approximately one year later, prior to the second Lyme disease season.

PF-07307405 is a multivalent protein subunit vaccine targeting outer surface protein A (OspA) of Borrelia burgdorferi, the bacterium responsible for Lyme disease. Vaccination induces antibodies that are ingested by ticks during feeding, inhibiting bacterial migration from the tick to the human host. The vaccine candidate is designed to provide coverage against six prevalent OspA serotypes circulating in North America and Europe.

The investigational vaccine was reported to be well tolerated, with no safety concerns identified at the time of analysis.

Lyme disease is the most common vector-borne infection in the Northern Hemisphere, with approximately 476,000 individuals diagnosed and treated annually in the United States. Early manifestations may include erythema migrans and nonspecific systemic symptoms, and untreated infection can progress to disseminated disease affecting the joints, heart, or nervous system.

Source: Pfizer