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Emory testing 'mix and match' booster shots for COVID-19 vaccines

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Quinn Eastman

Emory Children’s Center and the Hope Clinic of Emory Vaccine Center are participating in a clinical study that assesses the potential for booster shots of COVID-19 vaccines in a “mix and match” format.

Despite significant advances against COVID-19 in the United States, the pandemic is not over. Vaccine researchers at Emory are now examining booster shots and whether they could become a supplementary weapon to strengthen vaccine immunity against COVID-19.

Both Emory Children’s Center and the Hope Clinic of Emory Vaccine Center are participating in a clinical study that assesses the potential for booster shots of COVID-19 vaccines in a “mix and match” format. The study is led and supported by the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health. 

The study will include two groups: persons who have already received any of the emergency use authorized (EUA) COVID-19 vaccines and persons who have never received a COVID-19 vaccine and have not had a prior SARS-CoV-2 infection.

Study participants in the first group will receive a delayed booster vaccine, 12-20 weeks after completion of EUA approved vaccines, regardless of which COVID-19 vaccine was first administered. Study participants in the second group will initially receive the Moderna-mRNA-1273 EUA vaccines, followed by a booster vaccine. The study design is adaptive, so that vaccines developed to target emerging SARS-CoV-2 variants of concern can be rapidly assessed if necessary.

“Because of successful COVID-19 vaccination programs in the United States, it is becoming difficult to recruit people who haven’t been vaccinated,” says Srilatha Edupuganti, MD, MPH, associate professor of medicine (infectious diseases) at Emory University School of Medicine and principal investigator at the Hope Clinic site. "If you haven't been vaccinated yet, you can both get it done and help researchers prepare for the potential rollout of booster shots against COVID-19.” 

Mix and match is not a new approach in vaccine research, and researchers think combining different types of vaccines could potentially elicit a longer lasting and more robust immune responses. Also, booster shots could strengthen and possibly broaden the immune response to emerging variants of the virus. 

“This study will help us to understand if booster shots would be a practical strategy to protect against COVID-19,” says Christina Rostad, MD, assistant professor of pediatrics at Emory University School of Medicine and Children’s Healthcare of Atlanta, and protocol principal investigator at the Emory Children’s Center site.

The Mix & Match study is being conducted through the Infectious Diseases Clinical Research Consortium (IDCRC). Emory is one of ten IDCRC sites that will be participating in the Mix & Match study, and more information is available here

The Mix & Match study will assess safety, reactogenicity and immunogenicity of vaccine combinations in healthy adult volunteers in two age groups: 18 to 55 years old and those over 56 years old. It is open-label, meaning that no placebos are involved, and organizers and participants will know which vaccine a participant receives. 

Participants will be asked to come to the Hope Clinic or Emory Children’s Center to be vaccinated and to complete several follow-up visits. People who have not been vaccinated will receive two doses of the Moderna mRNA-1273 vaccine 28 days apart, and then a booster shot after a delay of greater than 12 weeks. Clinic visits include blood draws for safety monitoring and to see whether the booster vaccine resulted in a strong immune response. Clinical research staff will also be in contact with participants by telephone to keep track of symptoms.

Volunteers should not have a known history of COVID-19 or SARS-CoV-2 infection, and they cannot have health conditions that are associated with an increased risk of severe illness from SARS-CoV-2 infection, such as cancer, heart conditions, type 2 diabetes mellitus, severe obesity or chronic kidney disease.

Those interested in participating in the trial at the Hope Clinic, located in Decatur, can fill out a volunteer form or contact the Hope Clinic. The Emory Children’s Center vaccine research site’s preferred contact mode is via email:

About Infectious Disease Clinical Research Consortium (IDCRC)

The IDCRC, consisting of the Vaccine Treatment and Evaluation Units (VTEUs) and the IDCRC Leadership Group, was formed in 2019 to support the planning and implementation of infectious diseases clinical research that efficiently addresses the scientific priorities of NIAID. The consortium includes infectious diseases leaders and clinical researchers from Emory University, University of Maryland School of Medicine, Baylor College of Medicine, Cincinnati Children’s Medical Center and University of Cincinnati, FHI360, Fred Hutchinson Cancer Research Center, Johns Hopkins University, Kaiser Permanente Washington Health Research Institute, New York University, Saint Louis University, Vanderbilt University Medical Center, University of Alabama at Birmingham, University of Rochester, University of Washington, other affiliated sites and NIAID.

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