Pfizer Enters Phase Three Clinical Trial for Lyme Disease Vaccine

Pfizer and specialty vaccine company Valneva are set to begin testing their VLA15 vaccine in 6,000 individuals across areas in the US and Europe where tickborne Lyme disease is highly endemic. The Phase 3 clinical trial is the only Lyme disease vaccine trial currently in development and would be the only approved vaccine for Lyme disease if successful.  

Results from the Phase 2 study of VLA15 displayed strong efficacy in adults and children and acceptable safety profiles. The vaccine is a multivalent protein subunit that targets Borrelia burgdorferi bacteria, which causes Lyme disease. The vaccine has been in development since 2020, and according to Pfizer’s press release, it could be approved for use as soon as 2025 if it excels in the Phase 3 VALOR study.  

A previous Lyme disease vaccine — LYMERix — was available to eligible adults in the late 1990s, but it was eventually discontinued because of its low efficacy (76%), need for boosting, and low uptake. It was also found that the protection offered by the vaccine encouraged individuals to take more risks with outdoor activities in endemic disease areas and increased their risk of contracting other tickborne illnesses. 

Lyme disease is a tickborne infectious disease with 30,000 annual reported cases; however, far more people are likely infected each year without reporting their illness. Symptoms include rash, fever, headaches, fatigue, and joint pain, but untreated Lyme can lead to severe effects, including facial palsy, brain or spine inflammation, and heart palpitations.  

The prevalence of Lyme and other tickborne disease has gone through the roof in the last two decades, with some diseases increasing in prevalence by 16 times. Reported cases of Lyme more than doubled from 22,000 to 48,000 between 2004 and 2016.  

Behind these steep rises in tickborne disease is climate change, which has put pressure on animal species globally and contributed to zoonotic spillover. Zoonotic spillover describes the jump that viruses make from species to species, leading to disease emergence in new animals. Studies have found that environmental shifts associated with climate change have contributed to the rise of infectious diseases like West Nile virus, Lyme disease, HIV, bird flu, and others.  

One year ago, Pfizer created and received FDA approval for the first US vaccine to protect against tickborne encephalitis. The vaccine has a very high efficacy rate and has already been made available in other countries.