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# Pfizer Drops Many U.S. Lyme Trial Participants
- URL: https://www.fdaweb.com/pfizer-drops-many-u-s-lyme-trial-participants/
- Published: 2023-02-17T12:00:00.000Z
- Updated: 2026-09-14T18:16:34.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5153805

Pfizer has informed FDA it has decided to drop a significant percentage (about 50%) of U.S. participants enrolled in the Vaccine Against Lyme for Outdoor Recreationists (VALOR) Phase 3 study. A company statement [says](https://www.globenewswire.com/news-release/2023/02/17/2610346/0/en/Pfizer-and-Valneva-Issue-Update-on-Phase-3-Clinical-Trial-Evaluating-Lyme-Disease-Vaccine-Candidate-VLA15.html?ref=fdaweb.com) the participants are being dropped following violations of good clinical practice requirements at certain clinical trial sites run by a third-party clinical trial site operator.

“The discontinuation of these participants was not due to any safety concerns with the investigational vaccine and was not prompted by a participant-reported adverse event,” the statement says.

The company says the clinical trial is continuing at other unaffected sites and will enroll new participants at those sites.