President Joe Biden has challenged the US to administer 200 million COVID vaccination doses by the end of his first 100 days in office.

That is double the target of 100 million jabs he set in December and achieved earlier this month before his 60th day in office – an average of 2.5 million doses a day.

The US president is set to announce the new goal on Thursday in his first formal news conference since his term began on 20 January.