A phase 3 trial evaluating AstraZeneca’s investigational vaccine candidate, AZD1222, for the prevention of symptomatic coronavirus disease 2019 (COVID-19) has been initiated in the US.

AZD1222 utilizes a replication-deficient chimpanzee adenovirus to deliver a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein to induce a protective immune response. The multicenter, double-blind, placebo-controlled trial will evaluate the efficacy, safety and immunogenicity of AZD1222 for the prevention of COVID-19 in approximately 30,000 adult volunteers. Patients will be randomized 2:1 to receive 2 intramuscular injections of AZD1222 or placebo approximately 4 weeks apart. Patients will be followed for 2 years after their second vaccination.

The primary end point will assess the efficacy and safety of AZD1222 to prevent symptomatic COVID-19. Secondary end points include the prevention of SARS-CoV-2 infection regardless of symptoms, prevention of severe COVID-19, and the incidence of emergency department visits due to COVID-19. 

An independent Data and Safety Monitoring Board (DSMB) will provide oversight to ensure the safe and ethical conduct of the study. The study is being funded by the National Institute of Allergy and Infectious Diseases (NIAID) and the Biomedical Advanced Research and Development Authority (BARDA).

“Safe and effective vaccines will be essential to meet the global need for widespread protection against COVID-19,” said NIAID Director Anthony S. Fauci, MD. “Positive results from preclinical research led by NIH scientists supported the rapid development of this vaccine candidate, which has also showed promise in early-stage clinical trials.”

According to interim results from the phase 1/2 COV001 trial, AZD1222 elicited strong immune responses against SARS-CoV-2 in healthy adults. After receiving a single dose of the vaccine candidate, 95% of participants demonstrated a 4-fold increase in antibodies to SARS-CoV-2 1 month after vaccination. Moreover, AZD1222 induced a T-cell response in all participants that peaked by day 14 and was maintained 2 months after vaccination. Transient local and systemic reactions were common with AZD1222; these included temporary injection site pain and tenderness, pain, feverishness, chills, muscle ache, headache and malaise.

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Adults interested in participating in the trial, which is being conducted across 80 sites in the US, can visit coronaviruspreventionnetwork.org.

AZD1222 is also being evaluated in phase 2/3 trials in the UK, Brazil and South Africa, with additional trials planned for Japan and Russia; the trials are recruiting a diverse population of participants, including older individuals with comorbidities, healthcare workers, and others at high risk of exposure. Together with the US trial, the clinical program is expected to enroll 50,000 participants globally. The vaccine will also be evaluated in children once enough safety data has been collected in adult studies.

“Should clinical trials demonstrate the vaccine protects against COVID-19 disease and is approved for use, we will work hard to make it globally available in a fair and equitable manner as rapidly as possible,” said Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D, AstraZeneca.

For more information visit nih.gov.


Phase 3 clinical testing in the US of AstraZeneca COVID-19 vaccine candidate begins. https://www.nih.gov/news-events/news-releases/phase-3-clinical-testing-us-astrazeneca-covid-19-vaccine-candidate-begins. Accessed September 1, 2020.