Thousands of volunteers are being recruited for the next two phases in clinical trials that could lead to a coronavirus vaccine this year.
Scientists are looking for 10,260 people from across Britain to take the experimental jab, developed at the University of Oxford.
Experts began working on the jab in January. It is now considered one of the front-runners in the world’s race for a COVID-19 vaccine.
The vaccine, called AZD1222, proved safe in 160 healthy volunteers aged between 18 and 55 as part of the first phase of the trial.
Phases II and III involve vastly increasing the number of volunteers while expanding the age range to include elderly people, who are most at-risk of falling seriously ill with the infection.
They will assess whether the vaccine provokes a response from the immune system before looking at whether it can prevent people becoming infected.
‘The early stages of the Phase I trial have gone very well and we’re grateful for the many volunteers from Southampton who have come forward to help us assess the safety of the new vaccine and if healthy people can be protected from Covid-19,’ said Saul Faust, professor of paediatric immunology and infectious diseases at the University of Southampton.
‘We would now very much like to invite people from the Southampton area whose work brings them into possible contact with Covid patients or who are healthy and in the older age groups to take part in the next stage of trials of this Oxford Covid vaccine.
‘This is one of only four vaccine trials underway worldwide and could pave the way for a vaccine to be delivered later this year.’
Initially, researchers are aiming to recruit up to 620 new volunteers in three categories:
Researchers will assess the immune response to the vaccine in people of different ages, to determine how well the immune system responds in older people or children.
Adult participants in the phase II and phase III groups will be randomised to receive one or two doses of either a vaccine known as ChAdOx1 nCoV-19, or a licensed vaccine (MenACWY) that will be used as a ‘control’ for comparison.
ChAdOx1 nCoV-19 is made from a weakened version of a common cold virus from chimpanzees that has been genetically changed to make it impossible for it to grow in humans.
This has been combined with genes that make proteins from the Covid-19 virus (SARS-CoV-2) which play a key role in the infection pathway of the SARS-CoV-2 virus.
Phase I involved healthy adult volunteers to check the vaccine was safe. Around 1,000 doses were given out.
Production of the vaccine has already been scaled up ahead of the trial to prepare as early as possible for potential future deployment, the University of Southampton said.
AstraZeneca said this week it had the capacity to manufacture one billion doses of the University of Oxford’s potential Covid-19 vaccine and would begin supply in September.
The Brentford-based firm has signed a deal to mass-produce Oxford University’s promising COVID-19 jab and has agreements to supply 400million doses already.
US health officials – who have spent $1billion (£806,000) on funding the vaccine – have ordered 300million doses and hope to receive them for October.
Britain has a deal for 100million doses ‘as early as possible’ and ministers last week revealed they hoped a third of those would be ready for September.
Business Secretary Alok Sharma said the Government is ambitiously hoping to be in a position to roll-out a mass vaccination programme in the autumn of this year.
But top scientists dealt a blow to the hopes of millions of Britons longing for an end to the pandemic when they warned a working vaccine is unlikely to be ready until 2021.
Doubts have been cast about the jab – one of the front-runners in the world’s vaccine race – after studies on monkeys suggested it didn’t stop them getting infected.
The Oxford/AstraZeneca jab, now called AZD1222, is currently in trials on humans to prove it is safe and the team say it is progressing well.
Promising results that showed another experimental vaccine, made by US firm Moderna, could block the virus in humans sent stock markets into frenzy this week.
However, some scientists have warned that a vaccine might not be widely available until next year.
Professor Robin Shattock, head of mucosal infection and immunity at Imperial College London, told the BBC he believes vaccines ‘won’t be readily available for widescale use until the beginning of next year as the kind of most optimistic estimation.’
He has said there are around 100 coronavirus vaccines in development around the world and it will take months to get enough data to prove one works.
The one being made by his team at Imperial is being developed at an extraordinary pace, he has said, but it would be a ‘false expectation’ to think it was nearly ready.
Early clinical trials are intended to prove only that a vaccine is safe, and further large-scale studies must be done afterwards to see if it actually protects against the disease.
Professor Shattock said on Monday: ‘I think we need to distinguish two different things.
‘One of the hurdles is making vaccine doses, obviously AstraZeneca can do that and that is a good thing but that is very different to having the data that proves that the vaccine actually works.
‘We need to have those data to show that it is ready and appropriate to roll out. It may take quite some time to get that data, it is a numbers game.
‘And in fact as we are better at reducing the number of infections in the UK it gets much harder to test whether the vaccine works or not.
‘There are no certainties, no guarantees in developing any of these candidates so I think it is important not to have a false expectation that it is just around the corner.
‘It may be longer than any of us would want to think.’