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Lyme DiseasePhase 3NCT07500506

A Study to Learn About the Safety, Tolerability, and Immunogenicity of a Fifth Dose of 6-Valent OspA-Based Lyme Disease Vaccine

A Phase 3 study testing VLA15 in people with Lyme Disease, run by Pfizer at 22 sites in 2 countries.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts
Official record
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Trial summary

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. Read more about this study

Who is it for?
Ages 7 years and olderHealthy volunteers can take part
Conditions the study is for
Lyme Disease
What is being tested?
VLA15
Type of treatment
Injection or infusion
Could I receive a placebo?
Yes, some participants may receive a placebo
How many people
1,712 participants
Where
22 sitesin 2 countries
Study dates
8 Apr 2026to 4 Dec 2026
Phase
Phase 3
Are there results?
Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

  • Ages 7 years and older
  • All sexes
  • Healthy volunteers accepted
  • Child, Adult, Older adult

Who may be able to join

  • 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.

Who cannot join

  • 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.

Trial locations and contacts

22 sites in 2 countries. Contact the study team or a site near you to ask about taking part.

22 sites in 2 countries

United States19 sites, 19 recruiting
  • Northern Light Eastern Maine Medical Center

    Bangor, Maine, 04401

    Not yet recruiting
  • Northern Light Family Medicine and Residency Center

    Bangor, Maine, 04401

    Not yet recruiting
  • The University of Vermont Medical Center Inc.

    Burlington, Vermont, 05401

    Not yet recruiting
  • Smith Allergy and Asthma Specialists

    Cortland, New York, 13045

    Recruiting
  • Altoona Center For Clinical Research

    Duncansville, Pennsylvania, 16635

    Recruiting
  • Velocity Clinical Research, Providence

    East Greenwich, Rhode Island, 02818

    Not yet recruiting
  • Allegheny Health and Wellness Pavilion

    Erie, Pennsylvania, 16506

    Recruiting
  • Central Erie Primary Care

    Erie, Pennsylvania, 16508

    Recruiting
  • Hunterdon Medical Center

    Flemington, New Jersey, 08822

    Not yet recruiting
  • Smith Allergy & Asthma Specialists

    Horseheads, New York, 14845

    Recruiting
  • Preferred Primary Care Physicians, Preferred Clinical Research (Ofc 18)

    Pittsburgh, Pennsylvania, 15236

    Recruiting
  • Preferred Primary Care Physicians, Preferred Clinical Research - St.Clair

    Pittsburgh, Pennsylvania, 15243

    Not yet recruiting
  • Robert Packer Hospital

    Sayre, Pennsylvania, 18840

    Recruiting
  • Frontier Clinical Research, LLC

    Scottdale, Pennsylvania, 15683

    Recruiting
  • Northeast Clinical Trials Group

    Scranton, Pennsylvania, 18510

    Recruiting
  • Frontier Clinical Research, LLC

    Smithfield, Pennsylvania, 15478

    Recruiting
  • Preferred Primary Care Physicians

    Uniontown, Pennsylvania, 15401

    Not yet recruiting
  • Amherst Family Practice, P.C.

    Winchester, Virginia, 22601

    Not yet recruiting
  • University of Massachusetts Chan Medical School

    Worcester, Massachusetts, 01655

    Recruiting

Other trials in United States

Canada3 sites, 3 recruiting
  • Milestone Research Inc.

    London, Ontario, N5W 6A2

    Not yet recruiting
  • Diex Recherche Inc. Division Sherbrooke

    Sherbrooke, Quebec, J1L 0H8

    Recruiting
  • Stouffville Medical Research Institute Inc.

    Stouffville, Ontario, L4A 1H2

    Not yet recruiting

Other trials in Canada

About this study

Official title: A PHASE 3, RANDOMIZED, PLACEBO-CONTROLLED, DOUBLE-BLINDED STUDY TO EVALUATE THE SAFETY, TOLERABILITY, AND IMMUNOGENICITY OF A FIFTH DOSE OF 6-VALENT OSPA-BASED LYME DISEASE VACCINE, VLA15, IN HEALTHY PARTICIPANTS ≥7 YEARS OF AGE

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:

Read more
  • 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.

Read the detailed description

A Phase 3, Randomized, Placebo-Controlled, Double-Blinded Study to Evaluate the Safety, Tolerability, and Immunogenicity of a Fifth Dose of 6-Valent OspA-Based Lyme Disease Vaccine, VLA15, in Healthy Participants ≥7 Years of Age

Participants will be randomized in a 5:1 ratio to receive either one dose of VLA15 or placebo (saline) at the first visit. 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 1712 participants will be enrolled in the study.

Healthy individuals 7 years of age and older who have received 4 prior doses of active VLA15 from the C4601003 study, have a blood sample taken post dose 4, 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.

Conditions
Lyme Disease
Being tested
VLA15, Placebo
Medical subject headings
Lyme Disease

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

  • VLA15Biological

    VLA15 injection IM

  • PlaceboBiological

    Saline Injection

Study groups in NCT07500506
Study groupRoleWhat they receive
VLA15-1AExperimentalParticipants will receive a single injection in the muscle (IM) of VLA15 at Visits 1, two years after their 4th dose of VLA15
Receives: Biological: VLA15
VLA15-1BPlacebo comparatorParticipants will receive a single injection in the muscle (IM) of Saline at Visits 1, two years after their 4th dose of VLA15
Receives: Biological: Placebo
VLA15-2AExperimentalParticipants will receive a single injection in the muscle (IM) of VLA15 at Visits 1, one year after their 4th dose of VLA15
Receives: Biological: VLA15
VLA15-2BPlacebo comparatorParticipants will receive a single injection in the muscle (IM) of saline at Visits 1, one year after their 4th dose of VLA15
Receives: Biological: Placebo

What is being measured

The primary outcome is the main question the study is designed to answer.

  1. Percentage of participants reporting prespecified local reactions

    Measured: Within 7 days following each study intervention administration

  2. Percentage of participants reporting prespecified systemic events

    Measured: Within 7 days following each study intervention administration

  3. Percentage of participants reporting adverse events (AEs)

    Measured: Through 1 month following study intervention administration

  4. Percentage of participants reporting newly diagnosed chronic medical conditions (NDCMCs)

    Measured: Through study completion, up to approximately 12 months.

  5. Percentage of participants reporting serious adverse events (SAEs)

    Measured: Through study completion, up to approximately 12 months.

  6. Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to determine non-inferiority of Dose 5 compared to Dose 4 in all participants when there is a 1 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  7. Sero-response of anti-OspA IgG concentrations for each serotype (ST1-ST6).

    Difference in seroresponse rate between 1 month after Dose 5 and 1 month after Dose 4 for each serotype in all participants ≥7 years of age who received a fifth dose of VLA15 1 year after their fourth dose of VLA15.

    Measured: At 1 month after completion of Dose 5

Secondary outcomes (9)
  1. Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to determine non-inferiority of Dose 5 compared to Dose 4 in adult participants when there is a 1 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  2. Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to determine non-inferiority of Dose 5 compared to Dose 4 in all participants when there is a 2 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  3. Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to describe the immune response following Dose 5 compared to Dose 4 in pediatric participants when there is a 1 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  4. Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to describe the immune response following Dose 5 compared to Dose 4 in all participants (by age group) when there is a 2 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  5. Geometric mean fold rise (GMFR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to describe the immune response following Dose 5 compared to Dose 4 in all participants when there is a 1 or 2 year gap between Dose 4 and Dose 5.

    Measured: At just prior to Dose 5 and 1 month after completion of Dose 5

  6. Geometric mean concentration (GMC) of anti-OspA IgG concentrations for each serotype (ST1-ST6)

    Objective to describe the immune response following Dose 5 compared to Dose 4 in all participants when there is a 1 or 2 year gap between Dose 4 and Dose 5.

    Measured: At 1 month after completion of Dose 5

  7. Sero-response of anti-OspA IgG concentrations for each serotype (ST1-ST6).

    Difference in seroresponse rate between 1 month after Dose 5 and 1 month after Dose 4 for each serotype in adult participants ≥18 years of age who received a fifth dose of VLA15 1 year after their fourth dose of VLA15.

    Measured: At 1 month after completion of Dose 5

  8. Sero-response of anti-OspA IgG concentrations for each serotype (ST1-ST6).

    Difference in seroresponse rate between 1 month after Dose 5 and 1 month after Dose 4 for each serotype in all participants ≥7 years of age who received a fifth dose of VLA15 2 years after their fourth dose of VLA15.

    Measured: At 1 month after completion of Dose 5

  9. Sero-response of anti-OspA IgG concentrations for each serotype (ST1-ST6).

    Seroresponse rate at 1 month after Dose 5 using pre-Dose 1 and pre-Dose 5 seroresponse rates as baseline in all participants who received a fifth dose of VLA15 1 year and 2 years after their fourth dose of VLA15.

    Measured: At 1 month after completion of Dose 5

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

  1. First posted30 Mar 2026
  2. Study start8 Apr 2026
  3. Primary completion4 Dec 2026 (estimated)
  4. Study completion4 Dec 2026 (estimated)

Resources

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design
Study type
Interventional
Phase
Phase 3
Primary purpose
Prevention
Allocation
Randomised
Intervention model
Parallel groups
Masking
Triple blind
Who is masked
Participant, Investigator, Outcomes assessor
Enrolment
1,712 participants (estimated)
IDs, dates and publications
ClinicalTrials.gov ID
NCT07500506
Sponsor's protocol ID
C4601016
Status last verified
May 2026
First submitted
23 Mar 2026
Last updated
6 May 2026
Results posted
No
Data monitoring committee
Yes
FDA-regulated drug
Yes
FDA-regulated device
No
Individual data sharing
Yes: Pfizer will provide access to individual de-identified participant data and related study documents (e.g. protocol, Statistical Analysis Plan (SAP), Clinical Study Report (CSR)) upon request from qualified researchers, and subject to certain criteria, conditions, and exceptions. Further details on Pfizer's data sharing criteria and process for requesting access can be found at: https://www.pfizer.com/science/clinical\_trials/trial\_data\_and\_results/data\_requests.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing VLA15 in people with Lyme Disease, run by Pfizer at 22 sites in 2 countries.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 6 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 6 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 22 sites in United States, Canada. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Pfizer CT.gov Call Center (1-800-718-1021, ClinicalTrials.gov_Inquiries@pfizer.com), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Percentage of participants reporting prespecified local reactions (time frame: Within 7 days following each study intervention administration). The study lists 7 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 May 2026.

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