The so-called Oxford vaccine had an average efficacy of 70 percent in clinical trials, although one dosing regimen, which saw participants given a half dose of the vaccine followed by a whole dose one month later, showed an efficacy rate of 90 per cent.

"We think we have figured out the winning formula and how to get efficacy that, after two doses, is up there with everybody else," Soriot told the newspaper.

The AstraZeneca CEO said that he was unable to provide full details of the optimum dosing regimen for the vaccine at this stage, adding that the results will be published at a later date.

Russia's Sputnik V vaccine against COVID-19, as well as vaccines produced by Pfizer/BioNTech and Moderna, have shown efficacy levels in excess of 90 percent during clinical trials.

The UK government has submitted purchase orders for 100 million doses of the Oxford vaccine against COVID-19. Plans are in the works for the vaccine to be rolled out to the public from January 4, the Sunday Telegraph newspaper reported earlier in the day.