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Study of a Fifth Dose of VLA15 Lyme Disease Vaccine

This study is looking at the safety and how well a fifth dose of the VLA15 vaccine works to protect against Lyme disease. We want to see if people have any side effects and how their immune system responds after this booster shot. You might be able to join if you are healthy, at least 7 years old, and have already received four doses of VLA15 in a previous study (C4601003). You'll also need to have a blood sample available from after your fourth dose. Participants will receive one shot, either VLA15 or a saline (saltwater) placebo. The study will track any reactions or side effects for up to one month after the shot.

Study design
This is a Phase 3, randomized, placebo-controlled, double-blinded study involving about 1712 participants. Participants will be randomly assigned to receive either VLA15 or a saline placebo in a 5:1 ratio.
What's involved
You will receive one injection in your upper arm. The study will track any reactions for up to 7 days and other side effects for up to one month after the injection.
Compensation
Not stated in the trial record.
Follow-up
Participants will be followed for at least one month after receiving the study intervention to monitor for adverse events.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07500506

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

Recruiting
PHASE3Ages 7+InterventionalPrevention
Pfizer
~1,712 participants
Updated 2026-05-06 on ClinicalTrials.gov
What's tested:VLA15Placebo

At a glance

Recruiting sites
12 of 22 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Percentage of participants reporting prespecified local reactions
Measured over Within 7 days following each study intervention administration
+6 more outcomes measured

Conditions

Lyme Disease

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NCT07500506

Where you'd take part

This study runs at 22 sites. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

  • Allegheny Health and Wellness Pavilion

    Erie, Pennsylvaniano site contact published

    Recruiting

  • Altoona Center For Clinical Research

    Duncansville, Pennsylvaniano site contact published

    Recruiting

  • Amherst Family Practice, P.C.

    Winchester, Virginiano site contact published

    Not yet recruiting

  • Central Erie Primary Care

    Erie, Pennsylvaniano site contact published

    Recruiting

  • Diex Recherche Inc. Division Sherbrooke

    Sherbrooke, Quebec, Canadano site contact published

    Recruiting

  • Frontier Clinical Research, LLC

    Scottdale, Pennsylvaniano site contact published

    Recruiting

  • Frontier Clinical Research, LLC

    Smithfield, Pennsylvaniano site contact published

    Recruiting

  • Hunterdon Medical Center

    Flemington, New Jerseyno site contact published

    Not yet recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Study leadership

  • Pfizer CT.gov Call Center · STUDY_DIRECTOR · Pfizer

Who to contact

Pfizer CT.gov Call Center
[email protected]
1-800-718-1021
Email the study team

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Eligibility criteria

Inclusion

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

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.

What this trial measures

  • Percentage of participants reporting prespecified local reactionsWithin 7 days following each study intervention administration
  • Percentage of participants reporting prespecified systemic eventsWithin 7 days following each study intervention administration
  • Percentage of participants reporting adverse events (AEs)Through 1 month following study intervention administration
  • Percentage of participants reporting newly diagnosed chronic medical conditions (NDCMCs)Through study completion, up to approximately 12 months.
  • Percentage of participants reporting serious adverse events (SAEs)Through study completion, up to approximately 12 months.
  • Geometric mean ratio (GMR) of anti-OspA IgG concentrations for each serotype (ST1-ST6)At 1 month after completion of Dose 5

    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.

  • Sero-response of anti-OspA IgG concentrations for each serotype (ST1-ST6).At 1 month after completion of Dose 5

    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.