NEW YORK - A Covid-19 vaccine developed in the US that may only require one dose to be effective is on track to become the third approved for use in the UK.
The Janssen vaccine has reached stage three of clinical trials and could soon be granted emergency authorisation - a move that could help the UK government hit its target of vaccinating a total of around 13 million people by mid-February.
Britain has already ordered 30 million doses of the jab, developed by pharmaceutical giant Johnson & Johnson, with the option of 22 million more.
