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Marshfield Clinic Research Institute participates in trial for potential Lyme disease prevention vaccine

​​​Oct. 11, 2022

MARSHFIELD – Marshfield Clinic Research Institute is the sole participant from the United States' Midwest in a worldwide Pfizer Phase 3 clinical trial, Vaccine Against Lyme for Outdoor Recreationists (VALOR), to investigate the efficacy, safety and immunogenicity of their investigational Lyme disease vaccine candidate, VLA15.

Lyme disease is a common illness caused by a bacteria found in ticks. Bites from infected ticks can transfer the bacteria to humans and cause a characteristic rash, fevers, and fatigue. If untreated, Lyme disease can sometimes progress to more a complicated disease involving the heart, nervous system, or joints.

Currently, there are no approved vaccines available to prevent Lyme disease. The VALOR research study is evaluating if an investigational (study) vaccine is safe and effective for preventing Lyme disease in people who have been exposed through tick bites.

“Lyme disease is a threat for all of us in the Midwest who recreate outdoors in the summer," said Dr. Matthew Hall, a Marshfield Clinic infectious disease physician and researcher. “A vaccination that could provide some reassurance against contracting this life-altering disease would be a game-changer."

Joining a clinical trial is an important and personal decision for you and your family. We hope it is one you will consider.

Healthy adults and children 5 years of age or older who live in or often visit outdoor areas that may expose them to ticks may be eligible to participate. Trial participants cannot have been diagnosed with Lyme disease within three months of enrollment.

Activities that may increase the risk of Lyme disease include:

  • Live in or frequently visit areas where ticks that carry Lyme disease are found, such as wooded areas, tree lines, open fields, lakesides or riversides.
  • Outdoor occupations such as landscaping, forestry, wildlife or parks management.
  • Hiking, camping, fishing, hunting, or gardening.
  • Owning a pet that has returned with ticks attached after being outside.

Study participants will be randomly assigned to receive the study vaccine or a placebo (shot with no active ingredient).

This study will last about 30 months. During this time, participants will have at least seven in-clinic study visits, including 4-5 visits with blood draws. Additional blood samples may be needed if participants develop symptoms of Lyme disease. Over the course of the study, participants will need to report any changes in their health to the study team.

The study vaccine and study-related procedures will be provided at no cost. You do not need health insurance to take part in this study.

To learn more about this trial and to find out if you are eligible to participate, visit

“Data from this study will hopefully support the strong immunogenicity VLA15 demonstrated in in adults and children with acceptable safety and tolerability profiles in previous study phases," Dr. Hall said. “The data we've seen so far is promising and we're excited about its potential to help prevent Lyme disease."

​The randomized, placebo-controlled, Phase 3 VALOR study is planned to enroll approximately 6,000 participants 5 years of age and older. The study is being conducted at up to 50 sites located in areas where Lyme disease is highly endemic, including Finland, Germany, the Netherlands, Poland, Sweden and United States. 


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