A Study to Learn About Different Dosing Schedules of a Lyme Disease Vaccine in Healthy Adults

This is a Phase 3, randomized, parallel-group, placebo-controlled, double-blinded (third-party unblinded) study to evaluate the safety, tolerability, and immunogenicity of different vaccination schedules of the 6-valent OspA-based Lyme disease (LD) vaccine, VLA15, in healthy participants 18 through 44 years of age. Participants will be randomized in a 1:1:1:1 ratio to 1 of the 4 parallel study groups. Each participant will receive 4 doses of VLA15 and 1 dose of placebo (saline) at different time points. This study will use an external data monitoring committee (EDMC). The EDMC is independent of the Pfizer study team and includes only external members. The EDMC charter describes the role of the EDMC in more detail. Approximately 200 participants will be enrolled in the study. Healthy individuals 18 through 44 years of age who are willing to comply with all study procedures and provide signed informed consent will be enrolled. Pregnant or breastfeeding individuals and fertile individuals who are unwilling or unable to use effective contraceptive methods as outlined in this protocol will not be enrolled. Individuals who have contraindication to vaccination, conditions or treatments that can inhibit the ability to mount an immune response to a vaccine, or other conditions that may increase the risk of study participation will be excluded from this study. Individuals who have previously received a licensed or investigational vaccine for LD will also be excluded from this study.