The first UK patients have been injected with a coronavirus vaccine that experts are 80% sure will work.
Out of 800 people recruited for the medical trial, two volunteers have been chosen to receive the vaccine.
The vaccine was developed by a team at Oxford University over the course of three months.
Half of those chosen for the trial will receive the COVID-19 vaccine, and half will receive a control vaccine that protects against meningitis - but not coronavirus.
The design of the trial means patients will not know which vaccine they have received, but medics will.
Elisa Granato, one of the two chosen to first receive one of the jabs, said: "I'm a scientist, so I wanted to try to support the scientific process wherever I can."
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Sarah Gilbert, professor of vaccinology at the Jenner Institute, led the pre-trial research and said she was 80% confident the vaccine would be effective, reports the BBC.
She said: "Personally I have a high degree of confidence in this vaccine.
"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."
The vaccine is made from a weakened version of the common cold virus taken from chimpanzees and has been adapted so it cannot grow in humans.
After being injected into the patient, it enters the cells which start to produce coronavirus proteins.
This them kick-starts the immune system, prompting it to produce antibodies to activate killer T-cells that destroy the infection.
If a patient goes to encounter coronavirus again, the same antibodies and T-cells are triggered to target and stamp out the virus.
In the coming months, the two groups of people, hose who received the coronavirus vaccine and those who did not, will be compared to see if the trial has been successful.
Professor Andrew Pollard, leading the trial, said: "We're chasing the end of this epidemic wave.
"If we don't catch it we won't be able to tell whether the vaccine works in the next few months.
"But we do expect there will be ore cases in the future because this virus hasn't gone away."
A larger trial of around 5,000 people is expected to be launched in the next few months.
