BORRELIA BURGDORFERI, SEROTYPE 1, OUTER SURFACE PROTEIN A FUSED VIA A LINKER TO BORRELIA BURGDORFERI, SEROTYPE 2, OUTER SURFACE PROTEIN A

BORRELIA BURGDORFERI, SEROTYPE 1, OUTER SURFACE PROTEIN A FUSED VIA A LINKER TO BORRELIA BURGDORFERI, SEROTYPE 2, OUTER SURFACE PROTEIN A is the full name of the active substance in the investigational vaccine VLA15. The short label Borrelia Burgdorferi refers to the bacterium that causes Lyme disease. VLA15 is a 6-valent OspA-based vaccine candidate designed to protect against Lyme disease.

What is Borrelia burgdorferi?

Borrelia burgdorferi is a spirochete bacterium transmitted to humans through the bite of infected ticks. It is the primary cause of Lyme disease in North America and Europe. The substance described here is not the bacterium itself but a vaccine antigen based on outer surface protein A (OspA) from six different serotypes of Borrelia burgdorferi sensu lato. VLA15 is an investigational vaccine candidate with no marketing authorisation in these records.

How does Borrelia burgdorferi work?

The vaccine candidate VLA15 works by exposing the immune system to OspA proteins from six serotypes of Borrelia burgdorferi. OspA is a surface protein expressed by the bacterium while it resides in the tick gut. Vaccination with OspA induces antibodies that target the bacterium inside the tick before it can be transmitted to humans during a tick bite. Research on surface epitopes associated with protection against Lyme disease spirochetes has contributed to understanding how OspA-based vaccines may provide immunity.^[2]

Which conditions is it used or studied for?

• Lyme disease — a tick-borne infection caused by Borrelia burgdorferi sensu lato that can affect the skin, joints, heart, and nervous system.

How is Borrelia burgdorferi given?

In the Phase 3 trial, VLA15 was administered as a 0.5 ml solution for intramuscular injection.^[1] The placebo comparator was a 0.5 ml sodium chloride 0.9% solution given by intramuscular injection.^[1]

What do the clinical trials show?

One completed Phase 3 trial (NCT05477524) evaluated VLA15 in 9,400 participants for active immunization against Lyme disease.^[1] The trial was placebo-controlled and interventional. Its primary efficacy objective was to demonstrate the ability of VLA15 to prevent clinically and laboratory confirmed Lyme disease caused by Borrelia burgdorferi sensu lato during the Lyme disease season after completion of the primary vaccination series and booster dose.^[1]

Primary safety measures included the percentage of participants reporting local reactions such as pain at the injection site, redness, and swelling, as well as systemic events including fever, headache, fatigue, muscle pain, and joint pain. Adverse events, newly diagnosed chronic medical conditions, and serious adverse events were also recorded.^[1]

Primary immunogenicity objectives included demonstrating that immune responses to the six serotypes induced by VLA15 were equivalent across three independent lots, and that immune responses in children aged 5 to 17 years were noninferior to those in adults aged 18 to 44 years after the booster dose. Immune responses were measured using an anti-OspA quantitative immunological assay to determine antibody titers.^[1]