Work began in January on the vaccine, which uses a virus taken from chimpanzees and was developed by the University of Oxford’s Jenner Institute and the Oxford Vaccine Group.
The first phase of the trial involved 160 healthy volunteers aged between 18 and 55 years.
Now scientists want to recruit more than 10,000 people across the country for stages two and three, resulting in a considerable increase in the number of volunteers and an expansion of the age group to include adults and older children.
Adult participants in phase two and three groups will be randomized to receive one or two doses of a vaccine known as ChAdOx1 nCoV-19 or an authorized vaccine (MenACWY) which will be used as a “control” for comparison.
ChAdOx1 nCoV-19 consists of a weakened version of a common chimpanzee cold virus that has been genetically modified to make it impossible for humans to grow.
This has been combined with genes that produce proteins from the Covid-19 virus (SARS-CoV-2) that play a key role in the SARS-CoV-2 virus infection pathway.
Professor Pollard said the next phase of vaccine testing will focus on the immune response in older adults, adding: “We are now looking into whether older adults have a similar immune response, so let’s look at those on the front lines.
“There are two groups: the first are those over 55 and divided into 55 and 70 and those over 70. And in that group we are closely examining immune responses, particularly in older adults where immune responses are often a little weaker [than] in young adults. “
He said a second group of 10,000 frontline workers will participate in the study.