Updated May 4, 2021 at 3:43 PM ET

President Biden on Tuesday announced a new goal to administer at least one dose of a COVID-19 vaccine to 70% of American adults by the Fourth of July.

The administration also aims to have 160 million adults fully vaccinated by then, a push to improve the level of immunity in the country to the point where the coronavirus has less of an opportunity to spread and so that more public health restrictions can be lifted, administration officials told reporters.

As of Monday, more than 246 million vaccine doses have been administered across the United States. More than 56% of the adult population has received at least one dose, while 40% of adults have gotten two doses, according to the Centers for Disease Control and Prevention.

The July Fourth goal would mean about 100 million shots during the next 60 days — a slowdown from the earlier vaccination pace, and a recognition that those most eager to get the shot have already done so, administration officials said.

As part of the push to get more shots in arms, the White House told governors on Tuesday it will be tweaking the allocation system for vaccines. States currently receive doses each week based on population — a formula that will continue. But states will now be able to choose whether they want all of their allocation, or contribute some doses to a federal pool. That way, states that need more doses based on demand could draw from that pool, according to an administration official. The move marks a shift toward a model that governors such as Michigan's Gretchen Whitmer have called for to meet surges in new cases.

The president also plans to make vaccines more accessible by ordering tens of thousands of pharmacies to offer walk-in appointments, fund more pop-up and mobile clinics and allocate more doses of the vaccine to rural communities — where the pace of vaccinations, including among health care workers, is raising alarms.

"We're going to make it easier than ever to get vaccinated," Biden said in remarks Tuesday.

Looking ahead to adolescent vaccinations

The administration is also setting its sights on expanding vaccine access beyond the adult population. Biden is expected to announce plans for a push to get children between the ages of 12 and 15 vaccinated as soon as possible — if the Food and Drug Administration authorizes it. If that happens, doses would be distributed through pediatricians and family doctors, and by using the federal pharmacy program, which would make the vaccines available at about 15,000 pharmacies across the country, administration officials said.

Currently, only the Pfizer vaccine is approved in the U.S. for people as young as 16. A ruling on whether to allow children between 12 and 15 to receive the vaccine should come "shortly," Pfizer Chairman and CEO Albert Bourla told investors in a conference call Tuesday.

"I want American parents to know that if that announcement comes, we are ready to move immediately," Biden said.

The push to see more Americans vaccinated is part of Biden's effort to stamp out a pandemic that has upended the lives of millions of Americans and battered the national economy for more than a year.

Biden's predecessor, former President Donald Trump, launched the national vaccination program but faced criticism for his slow response to the pandemic, spreading misinformation about the virus and his slow endorsement of the vaccine to his supporters — many of whom have delayed getting it because of concerns and conspiracy theories about its safety.

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