Chief executive Pascal Soriot said it followed the accidental discovery that it performed best when half a dose was given, followed by a full one.
“Now that we’ve found what looks like a better efficacy we have to validate this, so we need to do an additional study,” Mr Soriot told Bloomberg.
It is likely to be an “international study, but this one could be faster because we know the efficacy is high so we need a smaller number of patients”, he added.
The development is unlikely to hold up regulatory approval in the UK, Mr Soriot said.
Further details have emerged about what Christmas will look like for Scotland following news this week that “bubbles” of three households will be able to mix for five days over the festive season.
The Scottish government has published new guidance confirming the bubbles are limited to no more than eight people over the age of 11. In contrast, the UK government has set no limits for the number of people in a bubble in England, saying only they should be “as small as possible”, while no guidance has been published yet for Wales and Northern Ireland.
There is further evidence coronavirus infections are levelling off in England. Data from the Office for National Statistics suggests infection rates are falling in a number of parts of England, including the North West, London and the South West but rising in the Midlands and the North East. However, it’s a mixed picture across the UK, with Wales and Northern Ireland seeing a fall in infections and Scotland an apparent rise.
Berlin is racing to open six mass vaccination centres capable of handling up to 4,000 people per day by mid-December, the project coordinator told Reuters on Thursday, as the city waits for authorities to approve the first vaccines.
An empty trade fair hall, two airport terminals, a concert arena, a velodrome and an ice rink will be turned into six vaccination centres where it plans to administer up to 900,000 shots against the coronavirus in the first three months.
Albrecht Broemme said plans envisage 3,000 to 4,000 people per day being ferried through each centre in the same way as shoppers are guided through IKEA stores in one direction.