Scientist pictured above, Elisa Granato, was the first volunteer to be injected and she said she volunteered because she wanted to try to support the scientific process.
Half of those who volunteered will receive the Covid-19 vaccine, and half a control vaccine which protects against meningitis but not coronavirus.
The design of the trial means volunteers will not know which vaccine they are getting, though doctors will. The vaccine was developed under three months by a team at Oxford University.
The research was led by Sarah Gilbert, professor of vaccinology at the Jenner Institute, led the pre-clinical research.
“Personally I have a high degree of confidence in this vaccine,” she said.
“Of course, we have to test it and get data from humans. We have to demonstrate it actually works and stops people getting infected with coronavirus before using the vaccine in the wider population,” she added.
The Coronavirus vaccine is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees that has been modified so it cannot grow in humans, according to BBC.
The Oxford team has already developed a vaccine against Mers, another type of coronavirus, using the same approach – and that had promising results in clinical trials.
The only way the Oxford team will know if the Covid-19 vaccine works is by comparing the number of people who get infected with coronavirus in the coming months from the two arms of the trial.
Prof Andrew Pollard, director of the Oxford Vaccine Group, who is leading the trial, said: “We’re chasing the end of this current epidemic wave. If we don’t catch that, we won’t be able to tell whether the vaccine works in the next few months. But we do expect that there will be more cases in the future because this virus hasn’t gone away.”
A larger trial, of about 5,000 volunteers, will start in the coming months and will have no age limit.
The Oxford team is also considering a vaccine trial in Africa, possibly in Kenya, where the rates of transmission are growing from a lower base.
The trial volunteers will be carefully monitored in the coming months. They have been told that some may get a sore arm, headaches or fevers in the first couple of days after vaccination.
They are also told there is a theoretical risk that the virus could induce a serious reaction to coronavirus, which arose in some early Sars animal vaccine studies.
But the Oxford team says its data suggests the risk of the vaccine producing an enhanced disease is minimal.