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, 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:

• 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.

Study Overview

• Status: Recruiting
• Conditions: Lyme Disease
• Intervention / Treatment: Biological: VLA15; Biological: Placebo

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.

• Study Type: Interventional
• Enrollment (Estimated): 1712
• Phase: Phase 3

Contacts and Locations

• Study Contact: Name: Pfizer CT.gov Call Center; Phone Number: 1-800-718-1021; Email: ClinicalTrials.gov_Inquiries@pfizer.com

Study Locations

• Canada
  • Ontario
    • London, Ontario, Canada, N5W 6A2
      • Not yet recruiting
      • Milestone Research Inc.
    • Stouffville, Ontario, Canada, L4A 1H2
      • Not yet recruiting
      • Stouffville Medical Research Institute Inc.
  • Quebec
    • Sherbrooke, Quebec, Canada, J1L 0H8
      • Recruiting
      • Diex Recherche Inc. Division Sherbrooke
• United States
  • Maine
    • Bangor, Maine, United States, 04401
      • Not yet recruiting
      • Northern Light Eastern Maine Medical Center
    • Bangor, Maine, United States, 04401
      • Not yet recruiting
      • Northern Light Family Medicine and Residency Center
  • Massachusetts
    • Worcester, Massachusetts, United States, 01655
      • Recruiting
      • University of Massachusetts Chan Medical School
  • New Jersey
    • Flemington, New Jersey, United States, 08822
      • Not yet recruiting
      • Hunterdon Medical Center
  • New York
    • Cortland, New York, United States, 13045
      • Recruiting
      • Smith Allergy and Asthma Specialists
    • Horseheads, New York, United States, 14845
      • Recruiting
      • Smith Allergy & Asthma Specialists
  • Pennsylvania
    • Duncansville, Pennsylvania, United States, 16635
      • Recruiting
      • Altoona Center For Clinical Research
    • Erie, Pennsylvania, United States, 16508
      • Recruiting
      • Central Erie Primary Care
    • Erie, Pennsylvania, United States, 16506
      • Recruiting
      • Allegheny Health and Wellness Pavilion
    • Pittsburgh, Pennsylvania, United States, 15236
      • Recruiting
      • Preferred Primary Care Physicians, Preferred Clinical Research (Ofc 18)
    • Pittsburgh, Pennsylvania, United States, 15243
      • Not yet recruiting
      • Preferred Primary Care Physicians, Preferred Clinical Research - St.Clair
    • Sayre, Pennsylvania, United States, 18840
      • Recruiting
      • Robert Packer Hospital
    • Scottdale, Pennsylvania, United States, 15683
      • Recruiting
      • Frontier Clinical Research, LLC
    • Scranton, Pennsylvania, United States, 18510
      • Recruiting
      • Northeast Clinical Trials Group
    • Smithfield, Pennsylvania, United States, 15478
      • Recruiting
      • Frontier Clinical Research, LLC
    • Uniontown, Pennsylvania, United States, 15401
      • Not yet recruiting
      • Preferred Primary Care Physicians
  • Rhode Island
    • East Greenwich, Rhode Island, United States, 02818
      • Not yet recruiting
      • Velocity Clinical Research, Providence
  • Vermont
    • Burlington, Vermont, United States, 05401
      • Not yet recruiting
      • The University of Vermont Medical Center Inc.
  • Virginia
    • Winchester, Virginia, United States, 22601
      • Not yet recruiting
      • Amherst Family Practice, P.C.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child; Adult; Older Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Triple

Number of Arms

4

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: VLA15-1A; Participants will receive a single injection in the muscle (IM) of VLA15 at Visits 1, two years after their 4th dose of VLA15	Biological: VLA15; VLA15 injection IM
Placebo Comparator: VLA15-1B; Participants will receive a single injection in the muscle (IM) of Saline at Visits 1, two years after their 4th dose of VLA15	Biological: Placebo; Saline Injection
Experimental: VLA15-2A; Participants will receive a single injection in the muscle (IM) of VLA15 at Visits 1, one year after their 4th dose of VLA15	Biological: VLA15; VLA15 injection IM
Placebo Comparator: VLA15-2B; Participants will receive a single injection in the muscle (IM) of saline at Visits 1, one year after their 4th dose of VLA15	Biological: Placebo; Saline Injection

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of participants reporting prespecified local reactions		Within 7 days following each study intervention administration
Percentage of participants reporting prespecified systemic events		Within 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)	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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 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.	At just prior to Dose 5 and 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5
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.	At 1 month after completion of Dose 5

Collaborators and Investigators

• Sponsor: Pfizer
• Investigators: Study Director: Pfizer CT.gov Call Center, Pfizer

Publications and helpful links

Helpful Links

• To obtain contact information for a study center near you, click here.

Study record dates

Study Major Dates

• Study Start (Actual): April 8, 2026
• Primary Completion (Estimated): December 4, 2026
• Study Completion (Estimated): December 4, 2026

Study Registration Dates

• First Submitted: March 23, 2026
• First Submitted That Met QC Criteria: March 23, 2026
• First Posted (Actual): March 30, 2026

Study Record Updates

• Last Update Posted (Actual): May 6, 2026
• Last Update Submitted That Met QC Criteria: May 4, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Vector Borne Diseases; Infections; Bacterial Infections; Bacterial Infections and Mycoses; Gram-Negative Bacterial Infections; Borrelia Infections; Spirochaetales Infections; Tick-Borne Diseases; Lyme Disease
• Other Study ID Numbers: C4601016

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: 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.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No