THE scientists working on Oxford University’s experimental coronavirus vaccine say it appears to be safe, causes few side effects and triggers and “induces the right sort of immune responses”.

If all goes well, a vaccine could even be ready before Christmas – though it’s unlikely it will be widely available.

The researchers yesterday sounded a note of caution, saying it’s still very early days, describing the progress so far as a “milestone on the pathway to being able to prove whether or not the vaccine can actually protect people”.

Nicola Sturgeon called the results, published in The Lancet yesterday, “encouraging”.

The UK has already ordered 100 million doses of the vaccine.

The trial has only been going since April, so it’s not clear how long the vaccine lasts.

Professor Andrew Pollard, the lead author on the study, told the BBC people might need more than one dose: “We need to know how long the immune response lasts after vaccination, and whether or not people might need booster doses of vaccines in the future in order to maintain their protection.”

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Asked if he was under any pressure to rush the trial, the academic said the scientists involved were “absolutely committed to conducting rigorous clinical trials to answer the question, ‘are we able to protect people with a vaccine or not?’

“And that takes time and it takes a huge amount of dedication for the enormous teams around the world who are trying to do that.

“But secondly, even if we wanted to rush, and we weren’t being good scientists and trying to do it properly, there’s a whole process beyond us around regulatory review of everything that we do.

“And then eventually the regulator has to decide whether the vaccine can be approved for use in populations both here and in other countries around the world.

“But even after that, we still need the policymakers to decide how it should be used.”

The trial included 1077 healthy adults aged 18-55 years with no history of Covid-19, and took place in five UK hospitals between April 23 and May 21. The participants either received the new vaccine or the meningitis vaccine. The research found that the vaccine stimulates an antibody and T-cell response.

Antibodies ate the proteins produced by the blood in response to antigens, which are harmful substances that come from outside the body, such as from viruses or bacteria.

If the non-specific immune cells which respond to any invader instantly cannot tackle it, the T-cells come into play.

They take two forms – helper T-cells and killer T-cells. The latter attack the virus directly.

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T-cell responses targeting the Sars-CoV-2 spike protein were markedly increased in the 43 participants studied, peaking 14 days after vaccination.

This level declined slightly by day 56 of the trial.

The vaccine, which is being developed by Oxford and pharmaceutical firm AstraZeneca, will now move onto the next stage of the trial, with more than 10,000 people expected to take part.

However, the trial will also be expanded into other countries as levels of Covid-19 are now so low in the UK it’s proving tricky to know if the vaccine is effective.

The researchers are to carry out a large trial involving 30,000 people in the US as well as 2000 in South Africa and 5000 in Brazil.

Health Secretary Matt Hancock praised the scientists working on the trial. He said: “A safe and effective vaccine is our best hope of defeating coronavirus and returning to life as normal.”