As incoming US President Joe Biden began signing executive orders to undo some of his predecessor Donald Trump's signature policies and took his first steps to address the pandemic, he said "There's no time to start like today.

Biden told reporters in the Oval Office as he began signing a stack of orders and memoranda, "I'm going to start by keeping the promises I made to the American people."

He signed 17 executive orders, memorandums and proclamations－the first he has endorsed to address the pandemic.

Biden imposed a national mandate requiring face masks and physical distancing in all federal buildings, on all federal land and by all federal employees.

He ended Trump's efforts to leave the WHO, sending Anthony Fauci, the US' top infectious disease specialist, to take part in the group's annual executive board meeting on Thursday.

Biden installed a coronavirus response coordinator－Jeff Zients－to oversee White House efforts to distribute vaccines and other medical supplies.

He reversed Trump's attempts to withdraw from international accords, beginning the process of rejoining the Paris agreement on climate change.

Biden also stopped funding for the construction of Trump's wall on the United States border with Mexico.

He signed an executive order revoking the Trump administration's plan to exclude noncitizens from the census count, and a second order aimed at bolstering the Deferred Action for Childhood Arrivals program that protects so-called Dreamers from deportation. Trump had sought for years to end the program, known as DACA.

Two Trump-era proclamations enforcing a ban on travel to the US from predominantly Muslim nations in Africa were ended.

Biden also directed the State Department to look for ways to address the harm caused to those prevented from traveling to the US due to the ban.

CNN reported seeing a calendar Biden plans to follow this month by centering each day on a specific theme. The White House did not confirm the report's accuracy.

According to CNN, on his first full day in office on Thursday, Biden would focus on the pandemic, while on Friday he would highlight his push for economic relief.

The report said the themes next week would include "Buy American", with an executive order on Monday increasing requirements for government purchases of goods and services from US companies.

Immigration would be the theme for Friday next week, when Biden plans to sign executive orders focusing on border processing and refugee policies, and also establish a family reunification task force.