Professor Sarah Gilbert, of the University of Oxford, described the results as promising but said there “is still much work to be done before we can confirm if our vaccine will help manage the Covid-19 pandemic”.
In research published on Monday in the journal Lancet, scientists said that they found their experimental Covid-19 vaccine produced a dual immune response in people aged 18 to 55 – provoking a T cell response within 14 days of vaccination and an antibody response after 28 days.
Oxford University has partnered with AstraZeneca to produce the vaccine globally, with the pharmaceutical giant already committed to making 2 billion doses.
The coronavirus vaccine candidate being developed by AstraZeneca and Oxford University induces a strong immune response and appears to be safe, according to preliminary trial results.
The early stage trial, which involved 1,077 people, has found that the vaccine causes few side effects and trains the immune system to produce antibodies and white blood cells capable of fighting the virus.
The UK government has ordered 100 million doses of the vaccine, while the US has similarly secured 300 million doses.
Larger trials evaluating the vaccine’s effectiveness, involving about 10,000 people in the UK, as well as participants in South Africa and Brazil, are still underway. Another big trial is slated to start in the US soon, aiming to enrol about 30,000 people.
Health Secretary Matt Hancock said the update on the vaccine was “very encouraging news”.
He tweeted: “We have already ordered 100 million doses of this vaccine, should it succeed.
“Congratulations to the scientists at UniofOxford & OxfordVacGroup and leadership of AstraZeneca.”
Explaining how the vaccine works, study lead author Professor Andrew Pollard, of the University of Oxford, said: “The new vaccine is a chimpanzee adenovirus viral vector (ChAdOx1) vaccine that expresses the SARS-CoV-2 spike protein.
“It uses a common cold virus (adenovirus) that infects chimpanzees, which has been weakened so that it can’t cause any disease in humans, and is genetically modified to code for the spike protein of the human SARS-CoV-2 virus.
“This means that when the adenovirus enters vaccinated people’s cells it also delivers the spike protein genetic code. This causes these people’s cells to produce the spike protein, and helps teach the immune system to recognise the SARS-CoV-2 virus.”