A Lyme disease vaccine from Pfizer and Valneva has proven more than 70% effective in its Phase 3 trial a step forward for the two drugmakers in the race to bring a new way to prevent the disease caused by infected ticks.
This vaccine candidate, which is called PF-07307405 or LB6V, and before that VLA15, was studied as a Phase 3 vaccine trial called the VALOR (vaccination against Lyme for Outdoor Recreation) in persons aged five years or older in regions endemic for Lyme disease. In March, the companies stated that in the two predetermined analysis, confirmed Lyme disease cases were decreased by73.2% and 74.8%.
There is no approved human Lyme disease vaccine available in the U.S. which makes these results big news. The Centers for Disease Control and Prevention says Lyme vaccine candidates are still being tested in clinical trials, and a Pfizer-Valneva candidate is among the most advanced programs.
The disease Lyme disease is caused by bacteria that are transmitted mainly after the bite of a blacklegged tick carrying the bacteria. It may initially present with symptoms like fever and headache, tiredness and a boreating of the skin or “target”. Lyme disease can sometimes cause long term health issues affecting the joints, nervous system and heart.
PF-07307405 is a six-valent outer surface protein a vaccine, which has been developed using OspA and is designed to protect against the various strains of the bacteria that causes Lyme disease in the US and Europe. The idea behind this method of design appears to be related to a vaccine that can achieve protection before injection of the pathogen into the body. OspA antibodies can fight the bacteria when it is still in the mouth of the bug; in doing this the pathogen may not be transmitted to a person.
In the Phase 3 VALOR trial, patients were followed over multiple Lyme disease seasons and randomly assigned to receive the vaccine or placebo. The trial population consisted of more than 9,000 subjects from the US, Europe and Canada. Subjects received the primary series of vaccinations, then a booster dose, to assess protection during later Lyme disease seasons.
There is a key caveat to the headline efficacy number. The number of Lyme disease cases was lower than had been previously expected in the study, and as a result the trial’s first primary analysis that was specified in advance did not reach its predefined cutoff for success. Pfizer and Valneva noted the second specified analysis, which showed the median was on the right side of the threshold, found the results still supported next with the vaccine.
The firms indicated that the vaccine turned out well tolerated at the time of the analysis and that no safety issues had emerged. The results will still need to be reviewed by regulators together with the full set of clinical data before they make a decision on approval.
The development program has now entered the regulatory phase. The European Medicines Agency accepted the validation of the Marketing Authorization Application for PF-07307405 submitted by Pfizer and Valneva in August 2026. Validation is the designation given to the acceptance of an application for scientific assessment not an approval of the vaccine candidate.
