The Lyme disease vaccine candidate jointly developed by the American pharmaceutical company Pfizer and the French company Valneva has shown good protective effects in two phase III clinical trials. The scientific research team therefore believes that the vaccine is expected to be approved for marketing as early as 2027. However, whether it can ultimately be approved by the U.S. Food and Drug Administration (FDA) also depends on how the regulatory agency evaluates the trial data - especially if some of the primary endpoints are not met, which is still variable.
Pfizer’s journey to develop a Lyme disease vaccine has been marked by optimism and setbacks. As early as 2022, there were expectations that the company was expected to bring the world's first Lyme disease vaccine to the market within a few years, but then the project was blocked in the late stages of the critical "Lyme Disease Vaccine Trial for Outdoor Recreational Populations" (VALOR). In the latest data released, companies hope that regulators will focus on the protective effect of the vaccine itself - the overall protective efficacy of the vaccine candidate exceeds 70% in infected people.
“Lyme disease can have serious consequences—patients and their families often face long-term symptoms that impact their daily lives, work, and health, but there is currently no vaccine available,” said Annalisa Anderson, senior vice president and chief vaccines officer at Pfizer. "The protective efficacy of over 70% in the VALOR study is very encouraging and gives us more confidence in the potential of this vaccine to prevent this disabling disease."
According to the U.S. Centers for Disease Control and Prevention (CDC), a total of 89,000 cases of Lyme disease were reported in the United States in 2023, but the actual situation may be far underestimated. Because many patients receive treatment for symptoms without a clear diagnosis, researchers estimate that the true number of infections each year may be close to 500,000. Lyme disease is mainly transmitted through the bite of an infected tick, commonly known as a "deer tick" (scientific name: Ixodes scapularis), which carries the Lyme disease-causing bacterium Borrelia burgdorferi. Many people do not realize they have been bitten by a tick before they develop symptoms such as fever, fatigue, joint pain, and rash. If the disease progresses further, it may also cause chronic cardiovascular and nervous system problems.
From an ecological perspective, this type of tick is not limited to parasitizing deer, but is also commonly found on the surfaces of rodents, birds and other animals, making it an extremely efficient vector of transmission. While seasonal weather changes themselves have limited impact on Lyme disease prevalence, global warming and rising humidity are expanding tick-friendly areas. An effective vaccine could significantly reduce the health burden of the disease for high-risk groups who frequent tick-infested areas, such as hikers, campers, and people who work and live in outdoor environments for long periods of time.
The vaccine candidate product announced this time is code-named PF-07307405 (also known as LB6V). Its mechanism of action is to target protein A (OspA) on the outer membrane surface of the Lyme disease-causing bacterium, thereby activating the human immune system and inducing the production of specific antibodies against the bacterium. Trial data showed that 28 days after the completion of the fourth dose of vaccination, the protective efficacy of this vaccine reached 73.2%, which was a significant advantage over the placebo group.
However, while jointly announcing with Valneva that the vaccine was "effective," the two companies also admitted that the project failed to fully meet the primary endpoint set in the phase three trial at a statistical level. One reason is that the actual observed incidence of Lyme disease in the trial was lower than expected. This phase 3 study included more than 9,000 subjects from the United States, Canada and Europe "high-incidence areas of Lyme disease", covering people aged 5 years and above. In this context, the company emphasized that although there are certain deficiencies in the statistical endpoints, from a clinical perspective, the relevant data are still "clinically meaningful", which is also one of the basis for the two companies to continue to submit marketing applications to the FDA.
In the eyes of the outside world, this statement may have a certain "optimistic interpretation" component, but as far as the current public information is concerned, PF-07307405 is still the most promising candidate product so far to become the world's first Lyme disease vaccine. The industry also generally expects that the complete three-phase research paper will further clarify the current statistical controversy after it is officially published, because a single statistical indicator is not a universal adjudication tool for scientific research.
“These results bring us one step closer to launching a much-needed Lyme disease vaccine,” said Thomas Lingelbach, CEO and Board Member of Varneva. "We are very grateful to our partner Pfizer for their firm investment in this project. Both parties hope to speed up the development process of this vaccine as much as possible." In previous stages of clinical trials, the vaccine candidate has passed safety evaluations. Therefore, even if we are cautious about the statistical results of the third phase, PF-07307405 is still generally regarded as the most likely vaccine product to achieve a breakthrough in the field of Lyme disease prevention and control.
At present, the results of the Phase II clinical study of this vaccine candidate have been published in the medical journal "The Lancet", while the complete data of the Phase III trial has not yet been peer-reviewed and has not yet been officially released publicly.