NCT07500506 · Pfizer
A Study to Learn About the Safety, Tolerability, and Immunogenicity of a Fifth Dose of 6-Valent OspA-Based Lyme Disease Vaccine
What this study is about
The purpose of this study is to learn about the safety effects of the Lyme disease vaccine (called VLA15), and its ability to protect people from Lyme disease after a 5th dose of the vaccine.
View original scientific description
The purpose of this study is to learn about the safety effects of the Lyme disease vaccine (called VLA15), and its ability to protect people from Lyme disease after a 5th dose of the vaccine. This study is seeking participants who: * are generally healthy and 7 years of age and older, * have already been vaccinated with 4 doses of VLA15 (from the VALOR study), and have blood sample taken post dose 4. * are not currently taking, or haven't recently taken, medicines like chemotherapy, blood products, or blood thinners. * 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 1 dose through a shot in the upper arm, either VLA15 or saline shot (saltwater). The study will compare the experiences of people receiving the study vaccine or saltwater shot. Participants will take part in this study for about 12 months. During this time, they will have 4 planned clinic visits. The clinic visits may include having a health check, giving a small amount of blood and getting the study vaccine or saltwater as a shot at the first visit.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Participants who are healthy as determined by medical history and clinical judgment.
- Participants willing and able to comply with all scheduled visits, IP receipt, and other procedures throughout the study.
- Able to provide Informed Consent.
- Participants must have received 4 doses of VLA15 in the C4601003 study, and have a V7 blood sample available.
Exclusion criteria
- Pregnant or breastfeeding participants.
- Allergies or contraindications to vaccines or their components.
- Health issues including: blood clotting deficiencies, immunodeficiencies, bone marrow disorder, or uncontrolled psychiatric conditions.
- Receipt of therapies to treat malignancies, blood/plasma products and immunoglobulins, systemic corticosteroids and immunosuppressants, or anticoagulant therapy in recent medical history.
- Recent or concurrent participation in a separate interventional study.
- Staff or direct family of the study site staff and Sponsor.
Where
- Bangor, Maine
- Worcester, Massachusetts
- Flemington, New Jersey
- Cortland, New York
- Horseheads, New York
- Duncansville, Pennsylvania
- Erie, Pennsylvania
- Pittsburgh, Pennsylvania
- Sayre, Pennsylvania
- Scottdale, Pennsylvania
- Scranton, Pennsylvania
- Smithfield, Pennsylvania
And 4 more locations — see the full list below.
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced May 6, 2026 · Source of record for eligibility and locations