Under European law a vaccine must be authorised by the EMA, but individual countries can use an emergency procedure that allows them to distribute a vaccine for temporary use in their domestic market.
Britain is still subject to those EU rules during the post-Brexit transition period which runs until the end of the year.
The UK's own medicines regulator, the MHRA, confirmed this in a statement last month.
And its chief executive, Dr June Raine, said on Wednesday that "we have been able to authorise the supply of this vaccine using provisions under European law, which exist until 1 January".