Biden says all US adults to be eligible for vaccines by May

President Joe Biden told US states to make all adults eligible for coronavirus vaccine by May 1, hours after he signed a $1.9 trillion stimulus bill into law.

In a forceful but somber speech from the White House on the first anniversary of the pandemic lockdown, Biden said if Americans pulled together there could be a greater sense of normalcy - and some backyard barbecue parties with small groups - on the US Independence Day holiday on July 4.

That date is a new goal for the president and a projection of hope amid a pandemic that has killed more than 530,000 people in the United States, the most of any country.

To achieve his summer target, Biden said he needed Americans' help.

"If we don't stay vigilant and the conditions change, then we may have to reinstate restrictions to get back on track," he said in an evening address from the White House, his first in television prime time since becoming president.

"We've made so much progress. This is not the time to let up. Just as we are emerging from a dark winter into a hopeful spring and summer is not the time to not stick with the rules," he said.

Republicans swiftly criticised Biden for his cautious approach. "What America needs now is to fully reopen our economy and our classrooms," House of Representatives Republican leader Kevin McCarthy said on Twitter.

Biden said he was ordering US states, territories and tribes to make all adults eligible to receive a coronavirus vaccine by May 1. The White House has said it would have enough vaccine supply to vaccinate the adult population by the end of May. About 10 per cent of Americans so far have been fully vaccinated.

Administration officials said he would deploy 4,000 more troops to help with the vaccine effort, bringing the total number to 6,000. The White House is also seeking to expand the pool of people able to administer shots to include dentists, optometrists, paramedics, veterinarians and medical students.

Biden campaigned last year on a promise that he would tackle the pandemic more effectively than Republican President Donald Trump, and he has sought to encourage and model behaviour, such as mask-wearing, that Trump eschewed.

In his speech, Biden took a swipe at his predecessor by saying the virus was initially met with "denials for days, weeks, then months, that led to more deaths, more infections, more stress, more loneliness".

Biden said hate crimes and harassment against Asian Americans must stop. Trump repeatedly referred to the disease as the "China virus."

He also encouraged Americans to keep up mitigation efforts - wearing masks, keeping social distance and practicing good hygiene - to stop the virus and its variants from spreading. A number of states have been loosening restrictions as Americans, like many people around the world, grow weary of pandemic life.

"Photos and videos from 2019 feel like they were taken in another era. The last vacation. The last birthday with friends. The last holiday with extended family," Biden said, recounting the toll the virus has wrought.

He said the country would come away from the crisis stronger. "We faced and overcame one of the toughest and darkest periods in this nation's history - darkest we've ever known," he said.