Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Our partners AstraZeneca have today announced the high-level results from the primary analysis of their Phase III trial of the ChAdOx1 nCoV-19 coronavirus vaccine in the US. They confirm that the vaccine efficacy is consistent with the interim analysis results announced on Monday 22 March 2021.

Example vaccine vial in clinic © John Cairns
  • Primary analysis, part of pre-specified trial protocol, follows interim analysis on Monday 22 March
  • Data are consistent with interim analysis, and will form submission by AstraZeneca to US FDA
  • Vaccine 76% effective against symptomatic COVID-19, and 100% effective against severe or critical disease and hospitalisation

This primary efficacy analysis included the accrual of 190 symptomatic cases of COVID-19 from the 32,449 trial participants, an additional 49 cases to the previously announced interim analysis.

In addition, results were comparable across age groups, with vaccine efficacy of 85% in adults 65 years and older. A key secondary endpoint, preventing severe or critical disease and hospitalisation, demonstrated 100% efficacy.

Read the full story on the University of Oxford website.