Ongoing booster vaccine trial seeks vaccinated volunteers

Researchers are still enrolling study participants who have not already received a vaccine booster against SARS-CoV-2. 

Media Contact: Susan Gregg - 206.616.6730 / 206.390.3226,

The Gritstone second-generation COVID-19 vaccine clinical trial is testing the safety, tolerability, and immune responses stimulated by different doses of investigational booster vaccines.

Researchers at the University of Washington School (UW) of Medicine continue to enroll volunteers in an investigational COVID-19 booster vaccine trial. Volunteers will participate in the second stage of a phase 1  trial.

The study is recruiting COVID-19-vaccinated persons who have not yet received a booster vaccine against SARS-CoV-2, the virus that causes COVID-19.

The Gritstone second-generation vaccines are different from current vaccines. These vaccines are designed to elicit an immune response to multiple SARS-CoV-2 proteins, in addition to the spike protein targeted by currently available vaccines made by Moderna, Pfizer and Johnson & Johnson. 

By targeting several coronavirus proteins, the investigational vaccines may provide enhanced protection against a wide variety of SARS-CoV-2 strains and variants. The vaccine candidates were developed by Gritstone bio, Inc., a biotechnology company headquartered in Emeryville, California. In monkey models of COVID-19 infection, the vaccines protected against experimental infection and resulted in high levels of SARS-CoV-2 antibodies. 

“As the SARS-CoV-2 virus continues to change, we are evaluating different booster vaccines that could elicit a broader and longer- lasting immune response,” said Dr. Anna Wald, professor of medicine, epidemiology, and laboratory medicine and pathology, director of the Virology Research Clinic at the UW School of Medicine, and the site principal investigator of the trial. 

“We are looking for COVID-19-vaccinated persons willing to forego booster vaccination and instead receive the investigational vaccine,” said Dr. Tia Babu, acting assistant professor of medicine in the Division of Allergy and Infectious Disease at the UW School of Medicine and one of the trial investigators.

To enroll, participants must be age 18 or older, healthy, without significant allergies, without a history of prior SARS-CoV-2 infection and have been vaccinated against COVID-19 at least four months prior to enrollment. Persons over age 60 are encouraged to participate.

Participants will be asked to:

  • Make 9 to 14 or more study clinic visits in-person and will also receive one to two telephone check-ins with the study staff over 12 to 14 months
  • Receive one or two injections of an investigational booster vaccine
  • Have blood drawn several times for safety monitoring and to see whether the vaccine resulted in an immune response
  • Keep track of how they’re feeling after the injection

Interested participants should contact: The UW Virology Research Clinic: 

For more information about the trial, visit The study’s Clinical Trials Identifier is NCT04776317.

The study is sponsored and funded under grant UM1 AI148573 by the U.S. National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and is being conducted through the NIAID-supported Infectious Diseases Clinical Research Consortium.

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