The Nature of Lyme Disease

Lyme disease is triggered by several closely related bacteria, including Borrelia burgdorferi, Borrelia afzelii, and Borrelia garinii. Infection occurs through the bite of an infected tick. In some instances, a characteristic bull's-eye rash may appear, signaling that the bacteria have entered the body.

The ticks responsible for spreading this disease are relatively small and can infect hosts during both their adult and nymph stages. Adult ticks are about the size of a sesame seed, while nymphs resemble poppy seeds, making them particularly challenging to detect. The risk of infection increases the longer a tick remains attached to the skin.

Although Lyme disease can be effectively treated with antibiotics, early detection is crucial, as many individuals may not realize they have been bitten. Delayed treatment can lead to a range of serious symptoms, including severe headaches, rashes, arthritis, irregular heartbeats, and neuropathy. Some patients may experience "Post-Treatment Lyme Disease Syndrome," which can persist for months even after the infection has been cleared.

With ticks that carry Lyme disease widespread across North America and Europe, a vaccine could significantly reduce the risk of infection, particularly for children and adults in high-risk areas. The Centers for Disease Control and Prevention (CDC) estimates that approximately 300,000 individuals are infected with Lyme disease each year in the U.S., while the World Health Organization reports over 350,000 cases annually in Europe.

Progress Toward a Vaccine

One of the significant challenges in developing an effective Lyme vaccine lies in the variety of Borrelia species responsible for the disease in different geographic regions. North America primarily sees B. burgdorferi, while Europe has four pathogenic species: B. burgdorferi, B. afzelii, B. garinii, and B. bavariensis. Therefore, an ideal vaccine would need to provide broad protection against all these variants.

The initial effort to create a vaccine involved using a protein called OspA from B. burgdorferi. This vaccine, known as LYMErix, was effective and successfully passed clinical trials but was withdrawn from the market due to concerns regarding adverse effects in some recipients.

In contrast, the new VLA15 vaccine takes a different approach. It still utilizes OspA but incorporates only a portion of the protein and includes fragments from six different serotypes. Specifically, it combines components from B. burgdorferi (serotype 1), B. afzelii (serotype 2), B. garinii (serotypes 3, 5, and 6), and B. bavariensis (serotype 4). The vaccine uses engineered proteins that consist of two OspA forms from various Borrelia serotypes, along with lipid modifications to enhance immune response.

Recent findings from the Phase II clinical trials were announced by Valneva. In the group that received the higher dosage, approximately 95% developed antibodies against one serotype, while about 80% showed antibodies for another. Notably, no serious adverse reactions were reported, and even participants previously exposed to Lyme-causing bacteria generated antibodies to the OspA serotypes included in the vaccine.

Given these promising results, Pfizer and Valneva are collaborating to advance the clinical testing and development stages. Future efforts will focus on monitoring safety and determining whether the antibodies produced by the vaccine induce any immune-mediated toxicity towards the Lyme-causing bacteria. As Valneva's CEO, Thomas Lingelbach, emphasizes, Pfizer's extensive development and commercial expertise will be instrumental in making VLA15 a reality for preventing Lyme disease in both children and adults.

Vaccine Insights

The first video, "Vaccines for Lyme Disease - Past, Present, and Future," discusses the historical context and future prospects of Lyme disease vaccination.

The second video, "This Anti-Tick Vaccine Could Fight Lyme Disease's Silent Epidemic," explores how the new vaccine could address the growing concern of Lyme disease.