22 March 2021
- Oxford-AstraZeneca coronavirus vaccine 79% effective against symptomatic COVID-19 overall
- Vaccine 100% effective against severe or critical symptomatic COVID-19
- No safety concerns reported
A Phase III study of the Oxford-AstraZeneca coronavirus vaccine conducted by AstraZeneca plc in the USA, Chile and Peru has shown that vaccine is safe and highly effective, adding to previous trial data from the United Kingdom, Brazil and South Africa, as well as real-world impact data from the United Kingdom.
In the trial, which recruited over 32,000 volunteers across all age groups, the participants received either two standard doses of the Oxford-AstraZeneca vaccine or a placebo vaccine, at a four-week interval. These data show that the vaccine is 79% effective against symptomatic COVID-19, and 100% effective against severe, or critical symptomatic COVID-19.
These results also add to the extensive safety data collected both in previous trials and through real-world vaccine roll out schemes. The independent Data and Safety Monitoring Board (DSMB) reported no safety concerns among the participants receiving at least one dose of the vaccine.
The absolute efficacy is higher in this new study than observed in the Oxford-led studies, as efficacy is affected by the protocol case definition (higher for more severe cases) and the population in which the study is conducted. Today’s findings are in line with findings from other major vaccine developers who studied efficacy in the US.
Andrew Pollard, Professor of Paediatric Infection and Immunity, and Lead Investigator of the Oxford University trial of the vaccine, said:
‘These results are great news as they show the remarkable efficacy of the vaccine in a new population and are consistent with the results from Oxford-led trials. We can expect strong impact against COVID-19 across all ages and for people of all different backgrounds from widespread us of the vaccine.’
Sarah Gilbert, Professor of Vaccinology, and co-designer of the ChAdOx1 nCov-19 coronavirus vaccine, said:
‘These new results from the large phase III trials in the US, Chile and Peru provide further confirmation of the safety and effectiveness of ChAdOx1 nCoV-19. In many different countries and across age groups, the vaccine is providing a high level of protection against COVID-19 and we hope this will lead to even more widespread use of the vaccine in the global attempts to bring the pandemic to an end.’
AstraZeneca will be submitting the data for analysis by the scientific community in peer-review literature, and to the regulators in the USA, the US Food and Drugs Administration (FDA) and for emergency approval for use.
Notes to editors:
For further information or to arrange an interview, please contact the University of Oxford press office at firstname.lastname@example.org or on +44 (0)1865 280528
For more about the Oxford vaccine project and team: www.ox.ac.uk/covid-vaccine
Previous papers published on this project:
- Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK.
M Voysey, S A Costa Clemens, S A Madhi, L Y Weckx, P M Folegatti, P K Aley, et al.
The Lancet 2020.
- Safety and immunogenicity of ChAdOx1 nCoV-19 vaccine administered in a prime-boost regimen in young and old adults (COV002): a single-blind, randomised, controlled, phase 2/3 trial. M N Ramasamy, A M Minassian, K J Ewer, A L Flaxman, P M Folegatti, D R Owens, et al. The Lancet 2020.
- Safety and immunogenicity of the ChAdOx1 nCoV-19 vaccine against SARS-CoV-2: a preliminary report of a phase 1/2, single-blind, randomised controlled trial. P Folegatti, K Ewer, C Green, A Douglas, A Hill, T Lambe, S Gilbert, A Pollard et al. The Lancet 2020.
- Evaluation of the immunogenicity of prime-boost vaccination with the replication-deficient viral vectored COVID-19 vaccine candidate ChAdOx1 nCoV-19. Graham, Lambe et al. NPJ Vaccines 2020.
- ChAdOx1 nCoV-19 vaccine prevents SARS-CoV-2 pneumonia in rhesus macaques. van Doremalen, Lambe et al. Nature. 2020.
- A booster dose enhances immunogenicity of the COVID-19 vaccine candidate ChAdOx1 nCoV-19 in aged mice. Lambe, Linterman et al. Med (2020).
- Intranasal ChAdOx1 nCoV-19/AZD1222 vaccination reduces shedding of SARS-CoV-2 D614G in rhesus macaques. Lambe, Munster et al. Pre-print bioRxiv (2021).
- ChAdOx1 nCoV-19 protection against SARS-CoV-2 in rhesus macaque and ferret challenge models. Lambe, Spence et al. Pre-print ResearchSquare (2021).
- Single Dose Administration, And The Influence Of The Timing Of The Booster Dose On Immunogenicity and Efficacy Of ChAdOx1 nCoV-19 (AZD1222) Vaccine. M Voysey, S A Costa Clemens et al. Pre-Print Preprints with THE LANCET (2021)
- Efficacy of ChAdOx1 nCoV-19 (AZD1222) Vaccine Against SARS-CoV-2 VOC 202012/01 (B.1.1.7). Emary, Golubchik et al. Pre-Print Preprints with THE LANCET (2021)
- Antibody evasion by the Brazilian P.1 strain of SARS-CoV-2. Screaton et al. Pre-print bioRxiv (2021).
For detailed information about the vaccine trial: covid19vaccinetrial.co.uk
Images: Credit: University of Oxford, John Cairns
- Oxford Vaccine Vial: https://www.dropbox.com/sh/uj7itywvcdvoudt/AADjI_sgCzcVzPpdvbUqrqcea?dl=0
- Mobile Clinic for trial volunteers: https://www.dropbox.com/sh/5z64831lyoe5kbr/AAA7PauOWZaOMqr5OV_QdYfOa?dl=0
- Oxford Vaccine Group labs: https://www.dropbox.com/sh/dk3qx3h9ili83jv/AAAmhT0hoDDE6LB2brwotkWta?dl=0
- Profile photos: https://www.dropbox.com/sh/jpql3ofnoal1gz7/AABY1Kt9NytSrLcswhsK-SZGa?dl=0
- Downloadable researcher interviews and b-roll for video editors and broadcast: https://vimeo.com/showcase/7803812 Please contact the News Office for a password:
NOTE: These are for downloading and editing by media outlets, not for uploading or using wholesale.
- Short explainer video for social media or embed: https://youtu.be/xHJ_RqeXXy0
About the Oxford COVID-19 vaccine
ChAdOx1 nCoV-19, now known as AZD1222 co-invented by the University of Oxford and its spin-out company, Vaccitech, is being trialled by the University’s Jenner Institute and Oxford Vaccine Group. The team started working to develop a vaccine against coronavirus in January 2020.
Developed at the Jenner Institute, the recombinant adenovirus vector ChAdOx1 nCoV-19 uses a viral vector based on a weakened version of the common cold virus (adenovirus) containing the genetic material of SARS-CoV-2 spike protein. After vaccination, the surface spike protein is produced, which primes the immune system to attack COVID-19 if it later infects the body.
Over 50,000 people to date have taken part in clinical trials of The ChAdOx1 nCoV-19 vaccine sponsored by the University of Oxford and AstraZeneca, and many more have received the vaccine through public vaccination programmes following emergency use licensure. It has been shown to be safe and well tolerated, although it can cause temporary side effects, such as a temperature, flu-like symptoms, headache or sore arm.
Our partners, AstraZeneca, have committed to delivering billions of doses of its COVID-19 vaccine across the globe in a broad, equitable, and timely way at no profit during the pandemic. This includes an agreement with the European Commission to supply up to 400 million doses, starting in early 2021 following the regulatory approval from the European Medicines Agency, with tens of millions of doses due to be supplied in February and March.
For more information on this commitment, visit: https://www.astrazeneca.com/content/astraz/media-centre/articles/2021/astrazenecas-covid-19-vaccine-european-union-supply-commitment.html
Not for profit information:
As part of our agreement with our partner AstraZeneca, the vaccine will be supplied on a not-for-profit basis for the duration of the pandemic and in perpetuity for low- and middle-income countries, with any future royalties received by the University of Oxford being re-invested in the medical sciences.
This trial is funded by the National Institute for Health Research, UK Research and Innovation, the Bill & Melinda Gates Foundation, the Lemann Foundation, and the South African Medical Research Council. We are grateful to the NIHR infrastructure provided through the NIHR Biomedical Research Centres and the NIHR Clinical Research Network at the UK study sites.
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