Coronavirus: Early trials suggest Oxford vaccine is 'safe' and triggers immune response
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Phase one and two trials involving about 1,077 people showed the injection led to them making antibodies and T-cells that can fight coronavirus.
The findings on the Oxford vaccine trial were published today (July 20) in The Lancet - a peer-reviewed general medical journal.
The results so far "hold promise", but it is still too soon to know whether this is enough to prevent people from becoming ill with Covid-19 and larger trials are under way.
Professor Sarah Gilbert, of the University of Oxford, said: "There is still much work to be done before we can confirm if our vaccine will help manage the Covid-19 pandemic, but these early results hold promise.
"As well as continuing to test our vaccine in phase-three trials, we need to learn more about the virus – for example, we still do not know how strong an immune response we need to provoke to effectively protect against Sars-Cov-2 infection.
"If our vaccine is effective, it is a promising option as these types of vaccine can be manufactured at large scale."
The vaccine - called ChAdOx1 nCoV-19 - uses a weakened version of a common cold virus (adenovirus) which causes infections in chimpanzees.
It has been genetically changed so it is impossible for it to grow in humans.
Researchers hope their version will make the body recognise and develop an immune response to the spike protein - recognisable in images of the virus - that will help stop Covid-19 from entering human cells and therefore prevent infection.
"A successful vaccine against Sars-Cov-2 could be used to prevent infection, disease and death in the whole population, with high-risk populations such as hospital workers and older adults prioritised to receive vaccination," Professor Gilbert added.
More than 10,000 people will take part in the next stage of the trials in the UK.
There will also be a large trial involving 30,000 people in the US as well 2,000 in South Africa and 5,000 in Brazil.
This trial aims to assess how well people across a broad range of ages could be protected from Covid-19.
It will also provide valuable information on safety aspects of the vaccine and its ability to generate good immune responses against the virus.