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

The purpose of this study is to learn about the safety and effects of the Lyme disease vaccine (called VLA15) when given at different time points. This study is seeking participants who: * are generally healthy and between 18 and 44 years of age, * have never had a vaccine for Lyme disease before, * are not currently taking, or haven't recently taken, medicines like chemotherapy, blood products, or blood thinners, and * are not pregnant or breastfeeding and do not plan to become pregnant while receiving the study vaccine. All participants in this study will receive a total of 5 doses through a shot in the upper arm. Four doses will be the study vaccine (VLA15), and 1 dose will be saltwater. The study will compare the experiences of people receiving the study vaccine at different time points. This will help see if the study vaccine is safe and will help understand its effect on the body. Participants will take part in this study for about 2 years. During this time, the participants will have 11 planned visits - 8 will be at the study clinic and 3 will be done over the phone. The clinic visits may include having a health check, giving a small amount of blood (about 20 mL or 4 teaspoons), and getting the study vaccine or saltwater as a shot.