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

RecruitingPhase 3Healthy volunteers welcome

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

Who can join

Ages 7 and older · All sexes · Healthy volunteers welcome

Full eligibility criteria

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.

About the study

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.

What is being tested

VLA15 (biological)
Placebo (biological)

Sponsor: Pfizer · Participants: 1,712 · Started: Apr 8, 2026

Contact the study team

Pfizer CT.gov Call Center · Phone: 1-800-718-1021

Official record on ClinicalTrials.gov — NCT07500506

Locations in the U.S.

Maine	Northern Light Eastern Maine Medical Center, Bangor (Not yet recruiting) Northern Light Family Medicine and Residency Center, Bangor (Not yet recruiting)
Massachusetts	University of Massachusetts Chan Medical School, Worcester
New Jersey	Hunterdon Medical Center, Flemington (Not yet recruiting)
New York	Smith Allergy and Asthma Specialists, Cortland Smith Allergy & Asthma Specialists, Horseheads
Pennsylvania	Altoona Center For Clinical Research, Duncansville Allegheny Health and Wellness Pavilion, Erie Central Erie Primary Care, Erie Preferred Primary Care Physicians, Preferred Clinical Research (Ofc 18), Pittsburgh Preferred Primary Care Physicians, Preferred Clinical Research - St.Clair, Pittsburgh (Not yet recruiting) Robert Packer Hospital, Sayre Frontier Clinical Research, LLC, Scottdale Northeast Clinical Trials Group, Scranton Frontier Clinical Research, LLC, Smithfield Preferred Primary Care Physicians, Uniontown (Not yet recruiting)
Rhode Island	Velocity Clinical Research, Providence, East Greenwich (Not yet recruiting)
Vermont	The University of Vermont Medical Center Inc., Burlington (Not yet recruiting)
Virginia	Amherst Family Practice, P.C., Winchester (Not yet recruiting)

Conditions

Lyme Disease

From ClinicalTrials.gov, data retrieved Sep 30, 2026. Each study sets its own eligibility; the study team decides who can join.