US President Joe Biden has made the pandemic his top priority on his first day in office, launching a COVID action plan as American infections reached 24.5 million.

Mr Biden has pledged to provide 100 million doses of the coronavirus vaccine during his first 100 days in office.

The US is the world’s worst-hit country but Mr Biden’s team says it has inherited a strategy from Donald Trump that is “so much worse than we could have imagined,” Jeff Zients, the new White House COVID-19 response coordinator, revealed.

Mr Zients told reporters there was no federal strategy under Mr Trump nor a comprehensive approach.

“As President Biden steps into office today, that all changes,” he said.

• Read: What to expect from the Biden administration

Mr Biden is poised to ramp up America’s vaccination program, expand testing and mask-wearing, safely reopen schools and businesses and advance racial equity.

His plan aims to increase vaccinations by opening up eligibility for more people such as teachers and grocery clerks.

A White House statement said the co-ordinated National Strategy would “guide America out of the worst public health crisis in a century”.

“We can and will beat COVID-19. America deserves a response to the COVID-19 pandemic that is driven by science, data and public health – not politics,” the statement said.

President Joe Biden signs his first executive order in the Oval Office of the White House. Photo: Getty

The new Democratic president is set to deliver remarks on his administration’s COVID-19 response later on Thursday (local time) and sign executive orders that will “jump-start” the strategy.

The new directives will include requiring mask-wearing on certain public transport, producing equipment to expedite vaccine production, establishing a COVID-19 testing board to ramp up testing, fostering research into new treatments and bolstering the collection and analysis of data to support an equitable pandemic response.

The coronavirus has killed more than 406,000, far more than in any other country.

Mr Biden’s medical chief Anthony Fauci said the US would remain part of the World Health Organisation (WHO) and join the COVAX program to supply vaccines to poor countries.

Mr Trump had previously halted funding to the WHO, to whom the United States is the largest donor, and announced a process to withdraw from the agency by July 2021.

A booklet titled “National Strategy for the Covid-19 Response and Pandemic Preparedness” rests on a table. Photo: AAP

WHO director-general Tedros Adhanom Ghebreyesus welcomed the news saying: “This is a good day for WHO and a good day for global health.”

“WHO is a family of nations and we are all glad that the US is staying in the family.”

The first batches of coronavirus vaccines are expected to go to poorer countries in February under the COVAX scheme run by the WHO and the GAVI vaccine alliance, WHO officials said this week, even as they raised concerns that richer countries are still grabbing the lion’s share of available shots.

Meanwhile Democrat House Speaker Nancy Pelosi has refused to reveal when the House would send its article of impeachment against Mr Trump to the Senate.

However she indicated she thought it was important to continue the process even though Mr Trump was no longer in office.

“Just because he’s now gone, thank God, you don’t say to a president, ‘Do whatever you want in the last months of your administration. You’re going to get a get-out-of-jail card free,’” Ms Pelosi said.

“I don’t think it’s very unifying to say, ‘Oh, let’s just forget it and move on.’”