“It’s not just a hunch and as every week goes by we have more data to look at. I would go for 87%, that’s my personal view. “
She added that having something ready by the autumn is “just about possible if everything goes perfectly”, but warned that “nobody can promise it’s going to work”.
The lockdown in the UK could make it more difficult to test the vaccine, as human contact is low, so researchers will have to conduct trials somewhere with a higher rate of transmission, to get a quicker result.
Earlier in the week, researchers at Southampton University said they had discovered that the virus has “low shielding” , meaning a vaccine could be easier to develop.
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The UK is at the forefront of vaccine funding, and pumped £ m into an international fund last month – the biggest contribution at the time for a vaccine.
The government has also said that it would be willing to buy millions of doses, should trials prove successful.
However, despite the optimism from Oxford, other vaccine developers have said it could be up to a year before something is ready to distribute .
Ministers have been under pressure to explain details of the government exit-strategy from the ongoing lockdown, but scientists say that it is too early to consider removing the widespread restrictions while the number of dead still rises.