The University is expanding the age range of volunteers, to include children and pensioners.
Trials of Oxford's potential coronavirus vaccine are now moving into the second phase.
More than 1,000 healthy adults have been involved in phase 1, and now, the University is moving into phase 2 and expanding to include children and pensioners.
It's looking to recruit 10,260 adults and children across the country, so it can assess their immune response to the vaccine.
After that, phase 3 will look at whether it can prevent people from catching Covid-19.
Oxford Uni says sdult participants in both the Phase II and Phase III groups will be randomised to receive one or two doses of either the ChAdOx1 nCoV-19 vaccine or a licensed vaccine (MenACWY) that will be used as a ‘control’ for comparison.
Professor Andrew Pollard, head of the Oxford Vaccine Group, said: "The clinical studies are progressing very well and we are now initiating studies to evaluate how well the vaccine induces immune responses in older adults, and to test whether it can provide protection in the wider population.
"We are very grateful to the huge support of the trial volunteers in helping test whether this new vaccine could protect humans against the pandemic coronavirus."
Mene Pangalos, Executive Vice President, BioPharmaceuticals R&D, AstraZeneca said: 'We are so proud to be collaborating with the University of Oxford to accelerate the development and globalisation of this potential new vaccine against COVID-19 infection.
"The speed at which this new vaccine has advanced into late-stage clinical trials is testament to Oxford’s ground-breaking scientific research.
"We will do everything in our power to engage with governments, multilateral organisations and partners around the world to increase production and distribution and ensure rapid, fair and equitable distribution of a globally accessible vaccine."
The Oxford study will provide valuable information on safety aspects of the vaccine and its ability to generate good immune responses against the virus.
Age groups now being enrolled for phase 2 are people:
- Aged 56-69
- Aged over 70
- Aged between 5-12 years
Some participants will be given an E-diary to record any symptoms experienced for 7 days after receiving the vaccine and if they feel unwell for the following 3 weeks.