Joe Biden has signed 10 new executive orders in a bid to curb the spread of coronavirus across the United States.
On his first full day in office, the newly-inaugurated president launched new measures on vaccines, masks and testing.
He hit out at Donald Trump’s handling of the pandemic, saying his predecessor lacked the “urgency, focus and co-ordination we needed”.
“We have seen the tragic cost of that failure,” Mr Biden said.
He warned that “things are going to continue to get worse before they get better”, predicted the death toll will reach 500,000 next month and said the roll-out of vaccines in the US had been a “dismal failure” so far.
The US has seen the highest number of COVID-19 cases and deaths of any country in the world.
Mr Trump, who left the White House for Florida on Wednesday, was much-criticised for his handling of the pandemic.
He caught the disease in October, after hosting a reception where guests were seen not social distancing or wearing masks.
And when a US journalist said Mr Trump told him he knew how dangerous the virus was but liked “playing it down”, former first lady Michelle Obama accused him of trying to “gaslight the American people by acting like this pandemic is not a real threat”.