Every adult in the United States will be vaccinated against the deadly coronavirus by April 19, President Joe Biden has announced, advancing by two weeks the previous May 1 deadline for open season for inoculations.

The president's announcement on Tuesday comes amid a fourth surge of COVID-19 cases in America, the world's worst-hit country, with an increase in infections among young adults.

"No more confusing rules. No more confusing restrictions," said Biden, at the White House, announcing that by May 19 everyone "18 or older will be eligible to be vaccinated."

The United States is still in a "life-and-death race" against coronavirus, Biden said as his administration raced through a record 150 million vaccine shots in just 75 days.

The new record is against his initial target of 100 million shots in 100 days. Biden has now set the goal of getting 200 million vaccines to his fellow countrymen in the first 100 days of his administration.

"But let me be deadly earnest with you: We aren't at the finish line. We still have a lot of work to do. We're still in a life-and-death race against this virus. Until we get more people vaccinated, we need everyone to wash their hands, socially distance, and mask up in a recommended mask from the CDC," Biden said at a vaccination site in a Virginia suburb of Washington DC.

"Think about it this way: Better times are ahead. And, as I've said before, we can have a safe, happy fourth of July with your family and friends, in small groups in your backyard. The real question is: How much death, disease, and misery are we going to see between now and then?" he asked.

The number of new cases are going up and hospitalisation too has increased, Biden noted.

The US is the worst-hit nation as it has more than 30,846,300 confirmed cases and over 556,500 deaths, according to figures from Johns Hopkins University COVID-19 tracker.

"That's lives that have been lost. What we do now is going to determine how many people we'll save or lose in the month of April and May and June before we get to July 4th," Biden said.

"So, please, until we're further along in this accelerating, successful, but still growing vaccination effort, please wash your hands. Practice social distancing. Wear a mask, as recommended by the CDC. Get vaccinated when it's your turn," he said and urged the American people to do their job.

Biden said beginning April 19, every adult in every state, every adult in the country is eligible to get in line to get a COVID vaccination.

The new eligibility date in two weeks will give all adults in the US a chance then to schedule appointments for their shots at community health centers, pharmacies, drive-through vaccination sites in parking lots and elsewhere.

Participating in a tour of a COVID-19 vaccination site, he met an Indian-American immigrant, Savia Khan. When asked by the president, she said she is from India. "Been to India, a number of times," Biden said.

"I raised my three kids here. Two--one is graduate, one is about to graduate, one is in 11th grade," Savia said. "I am proud to be part of America," she added.

"You are America. America is a nation of immigrants, that's who we are. And by the way, the vice president's mother was from India," Biden added.