Researchers seeking volunteers for COVID-19 vaccine study

By Wendi Hawthorne, Office of Public Affairs

COVID-19 vaccine

Carmel B. Dyer, MD, speaks to two trial participants at the UTHealth Clinical Research Unit at Memorial Hermann-Texas Medical Center. (Photo by: Roger Castro/UTHealth)

A Phase III clinical trial to assess if a potential vaccine is effective at preventing symptomatic COVID-19 is now open for enrollment by The University of Texas Health Science Center at Houston (UTHealth) in collaboration with Memorial Hermann-Texas Medical Center.

The study vaccine, AstraZeneca’s AZD1222, has been shown in early-stage human trials to produce a positive immune response. This trial seeks to enroll 30,000 individuals across the nation. The Houston research site is the UTHealth Clinical Research Unit at Memorial Hermann-Texas Medical Center.

“The global infectious disease research community has united to launch numerous research studies as we search for treatment and prevention strategies for this illness. The development of a vaccine for COVID-19 is a critical step to help us return to normal,” said Roberto C. Arduino, MD, the study’s lead investigator and professor of infectious disease with McGovern Medical School at UTHealth.

Participants must be 18 years or older, healthy or have medically stable chronic diseases, have no known history of SARS-CoV-2 infection, and be at increased risk of infection. This includes, for example, people with stable underlying medical conditions, those with a high risk of exposure at their work, those over age 65, residents of elder care facilities, or individuals from racial and ethnic groups that have been impacted in greater numbers by the pandemic, such as African Americans, Latinx, and Native Americans.

Trial participants will be administered two doses of either the experimental vaccine or placebo (sterile salt water) four weeks apart. Preliminary data has suggested that a single dose can provoke the two main mechanisms of the adaptive immune system – the humoral and cellular immune responses.

Humoral immunity is also known as antibody-mediated immunity, which are antibodies primed to attack the SARS-CoV-2, the virus that causes COVID-19, if the person is in contact with the virus after the vaccination. Cellular immunity relies on T lymphocytes (white blood cells) to attack cells infected with SARS-CoV-2 virus. T lymphocytes, often called T cells, are responsible for conferring long-term immunological memory. Adaptive immunity is acquired through either infection or a vaccination. The early research also revealed that after the second dose of the vaccine, the body’s antibody response was heightened.

Participants will be randomized in a 2:1 ratio with roughly 20,000 participants receiving two doses of the AZD1222 vaccine and 10,000 receiving two doses of a placebo. The trial is double-blind, meaning neither patients nor researchers know what study group participants are placed in.

The vaccine was developed by the University of Oxford and is composed of a weakened and nonreplicating version of the chimpanzee adenovirus that causes the common cold, which contains the genetic material encoding for the spike protein of the SARS-CoV-2 virus. This surface protein gives coronavirus its crownlike appearance and allows it to attach to and enter cells. The investigational vaccine is designed to promote the development of antibodies against the spike protein and prevent it from entering cells.

“This vaccine study is pivotal toward controlling the COVID-19 pandemic and it’s important that we reach out to the members of our community who have been especially impacted by this illness,” said Jonatan Gioia, MD, a research associate at McGovern Medical School at UTHealth and a project manager for the trial. Other co-investigators from McGovern Medical School include Carmel B. Dyer, MD, and Jessica Lee, MD, MS.

For more information on this trial visit, or email

To enroll in this trial visit (Site code: HART).

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, and the Biomedical Advanced Research and Development Authority (BARDA), part of the U.S. Department of Health and Human Services’ Office of the Assistant Secretary for Preparedness and Response, are providing funding support for the trial.