7 February 2021
In an analysis, submitted as a pre-print prior to peer-review publication, a two-dose regimen of the ChAdOx1 nCoV-19 vaccine provides minimal protection against mild-moderate COVID-19 infection from the B.1.351 coronavirus variant first identified in South Africa.
Efficacy against severe COVID-19 infection from this variant was not assessed. The analyses being submitted in the pre-print show the vaccine had high efficacy against the original coronavirus strain in South Africa.
Researchers from the University of Witwatersrand and others in South Africa and the University of Oxford, UK found that viral neutralisation by sera induced by the ChAdOx1 nCoV-19 coronavirus vaccine against the B.1.351 coronavirus variant were substantially reduced when compared with the original strain of the coronavirus.
These early data, have been submitted for scientific peer-review, appear to confirm the theoretical observation that mutations in the virus seen in South Africa will allow ongoing transmission of the virus in vaccinated populations, as has been recently reported even in those with prior infection due to earlier circulating variants.
In this study of approximately 2,000 volunteers who were on average 31 years old, mild disease was defined as at least one symptom of COVID-19. Protection against moderate-severe disease, hospitalisation or death could not be assessed in this study as the target population were at such low risk.
Work is already underway at the University of Oxford and in conjunction with partners to produce a 2nd generation of the vaccine which has been adapted to target variants of the coronavirus with mutations similar to B.1.351, if it should prove necessary to do so.
Shabir Madhi, Professor of Vaccinology and Director of the Vaccines & Infectious Diseases Analytics (VIDA) Research Unit at University of the Witwatersrand, and Chief Investigator on the trial in South Africa said:
‘Recent data from a study in South Africa sponsored by Janssen which assessed moderate to severe disease, rather than mild disease, using a similar viral vector, indicated that protection against these important disease endpoints was preserved.
‘These findings recalibrate thinking about how to approach the pandemic virus and shift the focus from the goal of herd immunity against transmission to the protection of all at risk individuals in population against severe disease.’
Andrew Pollard, Professor of Paediatric Infection and Immunity, and Chief Investigator on the Oxford vaccine trial, said:
‘This study confirms that the pandemic coronavirus will find ways to continue to spread in vaccinated populations, as expected, but, taken with the promising results from other studies in South Africa using a similar viral vector, vaccines may continue to ease the toll on health care systems by preventing severe disease.’
Sarah Gilbert, Professor of Vaccinology at the University of Oxford said:
‘Efforts are underway to develop a new generation of vaccines that will allow protection to be redirected to emerging variants as booster jabs, if it turns out that it is necessary to do so.’
‘We are working with AstraZeneca to optimise the pipeline required for a strain change should one become necessary. This is the same issue that is faced by all of the vaccine developers, and we will continue to monitor the emergence of new variants that arise in readiness for a future strain change.’
Note: these findings are early preliminary data, which will be submitted for peer review and will appear as a pre-print in the days ahead.
Notes to editors:
The data reflected in this release includes results from the trial conducted in South Africa: a multicentre, randomised double-blinded controlled trial on the safety and efficacy of ChAdOx1-nCoV19 in HIV-uninfected people. A total of 2,026 HIV-uninfected adults age 18 to <65 years were enrolled between 24 June and 9 November 2020 across seven sites in Gauteng and the Western Cape; 1,010 and 1,011 received at least one dose of placebo or vaccine, respectively. The median age was 31 years.
More information is available in the trial protocol: https://www.wits.ac.za/media/wits-university/news-and-events/images/documents/2021/ChAdOx1-nCoV-19_ZA_Protocol_v6.0.pdf
For further information or to arrange an interview, please contact the University of Oxford press office at email@example.com or on +44 (0)1865 280528
For further information, images or to arrange an interview, please contact Deborah Minors at the Wits University Press Office: firstname.lastname@example.org, + (0) 27722 404990
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)
For detailed information about the vaccine trial: covid19vaccinetrial.co.uk
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.
The potential vaccine entered Phase III clinical trials in May to study safety and efficacy in healthy volunteers. In total, nearly 24,000 volunteers have joined the University of Oxford sponsored trial, in sites around the UK (approximately 12,000 volunteers), Brazil (approximately 10,000 volunteers) and South Africa (approximately 2,000 volunteers). Interim efficacy and safety data were published in The Lancet in December, including an extensive safety database of over 74,000 ‘person months’ of safety data follow-up.
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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