An Efficacy, Safety, Tolerability, Immunogenicity, and Lot-Consistency Clinical Trial of a 6-Valent OspA-Based Lyme Disease Vaccine (VLA15)

The main purpose of this clinical study is to evaluate a 6-valent OspA-based Lyme disease vaccine (VLA15) for prevention of Lyme disease within North America and Europe. Approximately 9,400 healthy participants (this number excludes participants from 8 sites which were terminated for quality issues) 5 years and older will be recruited from areas with high levels of endemic Lyme disease to receive VLA15 or placebo (an inactive substance consisting of saltwater). Each participant will have about a 50% chance of receiving VLA15 and about a 50% chance of receiving placebo. A subset of participants will receive VLA15 from 3 different lots or placebo (1:1:1:3 ratio) to assess lot equivalence. Participants will receive a 3-dose primary vaccination series at about 0, 2, and 5 to 9 months and then receive a booster dose about 12 months after end of primary vaccination series. Vaccination of participants will occur at a time of year such that the primary series is completed before the peak Lyme disease season followed by a booster dose just prior to the beginning of the second Lyme disease season. A subset of participants will be followed for a third Lyme disease season. Comparison will be made between the Lyme disease cases of people receiving the study vaccine to those of the people who are not. This will help us determine if the study vaccine is safe and effective. If enrolled, participants will need to visit the research site at least 7 times during the study, and for a subset of participants up to 9 times. There will also be at least 5 telephone contacts. It is expected that each participant will take part in this study for up to about 2 and a half years. The subset of participants followed for a third Lyme disease season will take part in this study for up to about to 3 and a half years.