All adults in every U.S. state, Washington, D.C., and Puerto Rico are now eligible for a COVID-19 vaccine, meeting the April 19 deadline that President Joe Biden set two weeks ago.

“For months I’ve been telling Americans to get vaccinated when it’s your turn. Well, it’s your turn, now,” Biden said Sunday on a program called “Roll Up Your Sleeves” on NBC. “It’s free. It’s convenient and it’s the most important thing you can do to protect yourself from COVID-19.”

The United States is administering an average of 3.2 million doses a day, up from roughly 2.5 million a month before. More than 131 million people, or half of all American adults, had received at least one shot as of Sunday, according to the Centers for Disease Control and Prevention, and about 84.3 million people have been fully vaccinated.

Hawaii, Massachusetts, New Jersey, Oregon, Rhode Island and Vermont were the last states to expand eligibility, opening vaccinations to all adults today.

“It’s truly historic that we have already reached this milestone,” said Dr. Nandita Mani, the associate medical director of infection prevention and control at the University of Washington Medical Center.

After a slow start, the pace of vaccinations has risen considerably in recent months. Biden, who initially said he wanted states to make all adults eligible for a vaccine by May 1, moved the deadline up as vaccinations accelerated. Biden has also set a goal of administering 200 million doses by his 100th day in office, which the nation is on pace to meet with more than 192 million shots administered, starting on Inauguration Day.

The expansion of eligibility comes as medical officials investigate whether Johnson & Johnson’s one-shot COVID-19 vaccine is linked to a rare blood-clotting disorder. All 50 states suspended administration of the vaccine last week, after federal health officials recommended a pause.

Dr. Anthony Fauci, the nation’s leading infectious disease expert, said Sunday that federal regulators should come to a decision Friday about whether to resume Johnson & Johnson vaccinations. Although he said he did not want to get ahead of the CDC and the Food and Drug Administration, he said he expected experts to recommend “some sort of either warning or restriction” on the use of the vaccine.

Even if there is a link between the vaccine and the clotting disorder, the risk is exceedingly low, experts say.

Still, Mani said the pause was likely to harden the hesitancy of some Americans to get vaccinated.

At the same time, with the virus resurgent, public health experts are warning Americans not to let their guards down. The United States is averaging more than 67,000 new cases a day over the past seven days, up from over 54,000 a month ago, according to a New York Times database.

“Seventy thousand cases a day is not acceptable. We have to get that down,” said Barry Bloom, a research professor and former dean of the Harvard T.H. Chan School of Public Health.

He said more vaccinations would help, but people must remain vigilant about wearing masks and social distancing.

At its current pace, the United States will vaccinate 70% of its population by mid-June. But vaccine hesitancy could slow progress toward herd immunity, which will also depend on vaccinating children.

“We’re making tremendous progress, but we’re still in the race against this virus, and we need to vaccinate tens of millions more Americans,” Biden said on Sunday. “We could have a safe and happy Fourth of July with your family and friends in small groups in your backyard. That’s going to take everyone doing their part. Get vaccinated.”

Pfizer announced this month that it had applied for an emergency use authorization to make children ages 12 to 15 eligible for its vaccine. Moderna is expected to release results from its trial in young teenagers soon, and vaccinations in this age group could begin before school starts in the fall.

Trials in younger children are underway. Fauci also said Sunday that he expected children of all ages to be eligible for vaccination in the first quarter of 2022.

Although vaccinations have picked up in the United States, many countries still face dire vaccine shortages. About 83% of COVID-19 vaccinations have been administered in high- and upper-middle-income countries, while only 0.2% of doses have been administered in low-income countries, according to a New York Times vaccine tracker.

Dr. Funmi Olopade, director of the Center for Global Health at the University of Chicago, said it was crucial for the United States to step up its role in the global vaccination campaign as supply increases. The virus, left to spread around the world, could continue to mutate and threaten the nation’s economic recovery, she said.

It is in everybody’s “self-interest to provide whatever we can in the way of excess vaccines to low- and middle-income countries,” Bloom said.

© 2021 The New York Times Company